View Full Version : Staking cracks in the gas key a problem?
Just how much of a problem, if it is a problem, is it likely to be if the staking of a gas key cracks the key's metal? I ask because I purchased a BCG that has cracking at all four stake points.
If there is a potential for bits to come loose inside, I can see that being a problem akin to having a popped primer. And I suppose it calls into question how secure the gas key screws really are.
But I don't really know how liable the cracked metal is to start giving up pieces.
QuickStrike
06-09-09, 03:53
Somes pics would probably help.
there's a thread about this on TOS.... seems like a famous manufacturer used MIM gas keys....hence the cracking on stacking points
Kind of hard to take a good picture with what I have:
http://i150.photobucket.com/albums/s95/MMcfpd/LMT_stake_3.jpg
Take a round jewelers file and radius the crack area and you will be fine.
OldNavyGuy
06-09-09, 08:35
THAT.., is a big problem if it were mine, cracks in a BCG gas key can only lead to the cracks eventually growing and one day a minor KaaBoom !!
if it were mine i would go for a replacement or $$$$ returned, JFYI i have 4 half circle Colt carriers for sale, two never used and two slightly used, if interested, PM me
Yeah! I read a comment about LMT using MIM gas keys. WTF???
cracks in a BCG gas key can only lead to the cracks eventually growing and one day a minor KaaBoom !!
Once a crack is radiused out, it no longer exists and will absolutely not promote further cracking. The NRC, EPRI, and ASNT all agree that this true, and I sure bet they do more testing for my nuclear reactor and associated piping systems and it's weld conditions than Colt or LMT does on a gas key. Not to mention that if our material fails... thousands die or are evacuated. If a gas key fails, one paper plate lives, or one soldier may die. Who do you think knows more about meterial failure analysis?
I would bet my next pay check that a smoothly radiused area where that crack once was.... will forever end the issue.
If a crack like (linear flaw) is detected on any pipe system the area must be ground out and radiused to remove any stress risers created at the tips (extents) of the crack. This process, depending on severity of base material removed, will allow the part to remain in service and also remain on a standard inspection interval. No augmented examinations would be required.
That area is not in a load bearing area of the key, and to radius that small and isolated area that is above the load bearing zone effected by the clamping force (compressional forces that seal the key) will have zero effect on the parts expected performance or life.
You can feel free to toss it out and get a new one, but it is not something you need to do.
All that said, leaving a stress riser will promote propagation of the flaw and overall failure of the part.
Medicine Calf
06-09-09, 13:16
Is the round mold mark between the bolts indicative of the key being MIM?
http://m4carbine.net/showthread.php?t=20664
THAT.., is a big problem if it were mine, cracks in a BCG gas key can only lead to the cracks eventually growing and one day a minor KaaBoom !!
if it were mine i would go for a replacement or $$$$ returned, JFYI i have 4 half circle Colt carriers for sale, two never used and two slightly used, if interested, PM me
WHAT!!!! That is just displaced metal from the staking process...That is NOT going to cause crack promotion into the key...
I have seen LMT, BCM, Larue and even a Colt carrier just like that. Just pound down the high spot, no need to file.
Quick Fix in-stock @ BravoCompany: http://www.bravocompanyusa.com/ProductDetails.asp?ProductCode=BCM+Gas+Key
Blankwaffe
06-09-09, 17:51
Take a round jewelers file and radius the crack area and you will be fine.
Yeap....Thats exactly what I did with the one I have thats cracked at the stake.The main reason I did it was to knock the sharp edges down that had actually pulled a chunk of meat out of a finger.The gas keys are very hard and practically dulled a standard hobby type file.Had to use a diamond file and a wet hone to accomplish the task.
Gota couple thousand rounds of ammo through the LMT carrier/gas key in question with no issues.
Blankwaffe
06-09-09, 17:59
Is the round mold mark between the bolts indicative of the key being MIM?
http://m4carbine.net/showthread.php?t=20664
Yeap apparently so.At least based on what Ive read on the subject of MIM.
The picture shown does not look like a crack to me. I wouldn't worry about the key pictured at all.
Radiusing the end of a crack does not mean the problem is over, it means you've done all you can, and you hope the problem is over. I'm a toolmaker, I've dealt with cracks.
Mark15
Going4Broke
06-09-09, 20:29
Yeah this has become a hot topic on TOS and most there think it is a horrible flaw and that it may ruin your gun and that LMT has cut corners. I call BS big time for 2 reasons.
1) Has LMT ever put out an inferior product or any product without testing the hell out of it. . . . . Nope.
2) A MIM product like that actually is slightly stronger than a machined product if done correctly and because of it the medal is not as soft. When you try to stake it you take a very small amount of metal and displace it thus stretching it. Since it is not as soft as the machined keys it tends to form a VERY TINY crack in it at the thinest and weakest point. However since it is as strong as it is it is not going to break of any little chunk and ruin your rifle. Now, if each stake was cracked in 2 places then I would worry.
I agree with taking a small file to the crack as sort of a preventative measure if you feel inclined to do so. I have one of the new LMT BCG's and inspected it and found 2 of the 4 have that vry tiny hairline crack, but I am not worried one bit. After all, they have been out for over 8 months now I believe and not one incident of failure has occured and if it had, it would have been all over this and other sites.
Powder_Burn
06-09-09, 21:02
A MIM gas key might not be an issue but why bother when then are standard production alternatives that are proven?
2) A MIM product like that actually is slightly stronger than a machined product if done correctly and because of it the medal is not as soft.
Do you have any data on this? I'm no expert, but this is pretty contradictory to just about everything which I have read and experienced with MIM.
Blankwaffe
06-09-09, 22:17
Yeah this has become a hot topic on TOS and most there think it is a horrible flaw and that it may ruin your gun and that LMT has cut corners. I call BS big time for 2 reasons.
1) Has LMT ever put out an inferior product or any product without testing the hell out of it. . . . . Nope.
2) A MIM product like that actually is slightly stronger than a machined product if done correctly and because of it the medal is not as soft. When you try to stake it you take a very small amount of metal and displace it thus stretching it. Since it is not as soft as the machined keys it tends to form a VERY TINY crack in it at the thinest and weakest point. However since it is as strong as it is it is not going to break of any little chunk and ruin your rifle. Now, if each stake was cracked in 2 places then I would worry.
I agree with taking a small file to the crack as sort of a preventative measure if you feel inclined to do so. I have one of the new LMT BCG's and inspected it and found 2 of the 4 have that vry tiny hairline crack, but I am not worried one bit. After all, they have been out for over 8 months now I believe and not one incident of failure has occured and if it had, it would have been all over this and other sites.
Well I guess I should keep a eye ball peeled on the key staking in this case.The gas key on mine has three seperate cracks at each stake.Seen some pictures of others that were the same way here on the forum.Best way to describe it is that there is a crack at about 10 o'clock,12 o'clock and 2 o'clock at each stake.Roughly.
Appears the material fractured at the points where it was displaced,including at the base...Again the metal is extremely hard and I think is the root cause of the cracks.I do believe that if the screws were removed the metal at the stakes would probably break away looking at the cracks and the material displaced.Otherwise I think its retained against the screws from being folded in at that point.
The hardness of the part is probably how LMT got around not using hard chrome on the key bores as well.
I had my boxers all wadded up over the non chromed key bore and possible MIM sometime back...Im not going to repeat it in this case.
Personally Im just going to run the gas key until I see an issue,and then LMT can deal with it.Otherwise I'll replace it with a BCM gas key when the gas tube needs to be replaced from wear and tear of use.
Radiusing the end of a crack does not mean the problem is over, it means you've done all you can, and you hope the problem is over. I'm a toolmaker, I've dealt with cracks.
Mark15
I would have to agree. Radiusing the crack just takes out the stress risers. It reduces the chance that the crack/new cracks will propagate. It doesn't guarantee that no new cracks will form.
MMcfpd,
Is your BCG an LMT, or some other brand? If an LMT, I bet if you contact them with your concerns, they will be responsive to you. If LMT is making their gas keys by MIM now, I expect they would appreciate the feedback, and perhaps they will even replace it for you if it proves to be substandard.
I didn't name the manufacturer initially as I just wanted to find out what, if any, problem the situation might present. But there doesn't seem to be much confusion about where the BCG originated.
The following email was sent a couple of days ago:
Greetings,
Today I received a new LMT semi-auto AR-15 bolt carrier group purchased from Bravo Company. The staking of the gas key hex screws has cracked the metal of the key at all four staking points and I want to know if this is cause for concern about the reliability or longevity of the assembly. Please advise.
Thank you for your time,
XXXXXX
Grant has said elsewhere that they will be providing a formal reply to concerns about the gas keys, so we'll see what they say. Opinion here and at TOS does not reveal a consensus so far.
For the record, properly done MIM will never be stronger than a properly done billet or forging of the same size.
The reason is grain structure of the metal. MIM has no grain structure.
Mark15
OldNavyGuy
06-10-09, 08:47
Once a crack is radiused out, it no longer exists and will absolutely not promote further cracking. The NRC, EPRI, and ASNT all agree that this true, and I sure bet they do more testing for my nuclear reactor and associated piping systems and it's weld conditions than Colt or LMT does on a gas key. Not to mention that if our material fails... thousands die or are evacuated. If a gas key fails, one paper plate lives, or one soldier may die. Who do you think knows more about meterial failure analysis?
I would bet my next pay check that a smoothly radiused area where that crack once was.... will forever end the issue.
If a crack like (linear flaw) is detected on any pipe system the area must be ground out and radiused to remove any stress risers created at the tips (extents) of the crack. This process, depending on severity of base material removed, will allow the part to remain in service and also remain on a standard inspection interval. No augmented examinations would be required.
That area is not in a load bearing area of the key, and to radius that small and isolated area that is above the load bearing zone effected by the clamping force (compressional forces that seal the key) will have zero effect on the parts expected performance or life.
You can feel free to toss it out and get a new one, but it is not something you need to do.
All that said, leaving a stress riser will promote propagation of the flaw and overall failure of the part.
i do not doubt you one bit, and i agree with the radiused idea, i have done it on non gun (aircraft, jet engine compressor blades, automotive, etc.) BUT ! as i said, if it were mine i would ask for a refund or replacement, as for your next pay check, i'll bet it is safe ;)
I don't see the cracks themselves as necessarily being a problem if they don't propagate from use. The real issue I see is the fact that LMT quietly substituted a different material and lining on a critical piece of the system (assuming that these do indeed prove to be MIM and not chromed). The cracks are just a sign of that.
I just checked the carried on a LMT I bought late last year - no cracks and no circle between the bolts. It does appear this is a recent change. I'm eagerly awaiting LMT's response.
I don't see the cracks themselves as necessarily being a problem if they don't propagate from use.
Just to let ya know, all cracks will propagate if subjected to temperature variances, seismic loading, pressure fluctuations, or compression/tension stress. Depending upon material type and multiple other variables you (an engineer) can calculate growth and plot a failure analysis of a part and schedule for safe replacement prior to componant failure. That is the basic idea of my job :) I provide the information about the flaw to the engineer, he does the analysis.
ASME and ASNT agree that all flaws subjected to the above forces will grow, some will branch and go multiple directions, some will folow the wild IGSCC (inter-granular stress corossion cracking, cracking along grain structures and boundaries within the part) and eventually make a part unfit for service. Your rifle, depending on use frequancy, may or may not have a short term effect. It could take years, it could take months. Internal flaws can be monitored and left alone if they are small enough, flaws open to the surface can never be left alone due to the fact that the surface flaws of the material will always propagate. Internal (volumetric) flaws can be extremely slow growing as they seek the surface, but again this depends on the variables applied to the part.
Think of metel like glass, only much slower to respond. Once you chip or crack your glass....it is going to spread. Once you apply a stress riser (crack or other flaw as well as machining marks/sharp edges/tooling marks/storage and handling damage and much more into a piece of metel that was not designed robust enough to overcompensate for that flaw... it is going to grow the flaw until one day it fails.
I will hold to my original thought that this is above the area of the gas key that sees force from the bolts that are inserted and TQ'ed down, so the only forces applied are temperature and seismic effects from shooting. By using a dremel or rat-tail file to dress out the flaw (crack or not, it is a surface flaw) by rounding and radiusing out the area of concern you will render the part able to be safely returned to service with no expectations of future issues.
Now I could be wrong....... what the hell do I know. I'm just a nuclear NDE tech with 20 years experiance.
The truth is that we do NOT know how a MIM gas key will last. Typically we NEVER see gas keys break (just the bolts holding them onto the carrier).
LMT is going to do one of three things:
1. Tell us there is not issue.
2. Tell us to send it back to them for a new gas key.
3. Tell us to shoot it and if you break it, they will warranty it.
C4
Long Response
Ok. My point (if you read my post) was that the cracks aren't the main issue IF they don't propagate. It you're certain that they will propagate without some dressing of that flawed area, then it's an issue.
Heavy Metal
06-10-09, 16:34
I saw some ruined gas keys in the service when I was an armorer.
They were damaged when dropped on concrete during cleaning.
I have three LMT FA BCGs and none have these marks, I received mine last fall but before the election. Has anybody heard of or seen one that has broken yet? BCM and Stag have replacement parts available now. With LMT's back log I'm not sure I would send one back even for a free replacement. Spare gas keys and screws are part of my spare parts kit.
Blankwaffe
06-10-09, 20:37
I have three LMT FA BCGs and none have these marks, I received mine last fall but before the election. Has anybody heard of or seen one that has broken yet? BCM and Stag have replacement parts available now. With LMT's back log I'm not sure I would send one back even for a free replacement. Spare gas keys and screws are part of my spare parts kit.
Yeap,my feeling on it is exactly the same.I keep at least one spare BCG on hand at all times just for that purpose.For $20.00 you can replace the gas key with a BCM or similar if a problem does appear,or spend $10.00 in shipping the BCG back and then having to wait for it to return.I'll just swap the part if needed and go with it...
I don't know if anyone has mentioned this yet, but the TOS thread has been updated with scans of the official statement from LMT. LMT says the gas keys are an improvement, but would neither confirm nor deny that they are MIM. I don't know how I feel about their response. I would also like to see how some of these gas keys hold up in long run before trusting my life to one.
That being said, I have a F/A BCG scheduled to ship from LMT in about a week (supposedly). Would you guys feel comfortable using one of the "new" gas keys in a duty rifle? I'm trying to decide whether to use it or whether set it aside as a spare and try to get a BCM or Colt carrier/gas key.
spamsammich
06-12-09, 12:35
I have no qualms about using the LMT BCG. Much ado about nothing IMHO. This whole debacle makes me hate the errornet even more. I was over at Rainier yesterday and those poor guys must field dozens of calls a day about this now. Oh well, return your LMT bcgs fellas, more for me to buy ;)
Here is the letter that LMT has issued.
C4
http://www.gandrtactical.com/images/archive/LMT/Gas%20Key%20Study%20Response%20June%202009.pdf
Blankwaffe
06-12-09, 13:23
Here is the letter that LMT has issued.
C4
http://www.gandrtactical.com/images/archive/LMT/Gas%20Key%20Study%20Response%20June%202009.pdf
Thanks Grant.
I was wanting to see an actual legible copy of the LMT response letter.
Seeing as how the complaints are from people noticing cracking at the staking sites and not failed gas keys, my hunch is that this is much ado about nothing. Having said that, LMTs response is pathetic, at best. If it's such a great improvement why not come out and say "Yes, it's MIM. Would you like a sample to test?"?
I have one of these LMT BCG's that I got from Grant when I ordered my BCM upper last year.
So what does this letter mean, exactly?
I'm reading that the carrier key is okay and that the cracks are due to surface hardness of the metal and not because the metal used for the part is inferior. And for what the part does the process of manufacturing the part creates a part the meets or exceeds the milspec anyway.
Is that right?
I originally wanted a BCM part when I made my order and Grant told me this LMT BCG is good. I trust him (regardless of the conspiracy theory crap I read on TOS) and I think that the LMT part I got from him is good to go. I've been shooting this gun exclusively since I got it and it has worked perfectly so far.
Going4Broke
06-12-09, 16:43
I have no qualms about using the LMT BCG. Much ado about nothing IMHO. This whole debacle makes me hate the errornet even more. I was over at Rainier yesterday and those poor guys must field dozens of calls a day about this now. Oh well, return your LMT bcgs fellas, more for me to buy ;)
+1. Has anyone every known LMT to make an inferior product or part?? didn't think so.;)
I certainly don't want to stifle innovation or claim that it's bad for companies to try new and potentially better materials and methods. It also appears that LMT did some homework and testing on this new part, and I own a complete LMT SBR that runs strong - so I have no complaints generally about the company.
Having said that, I still find this highly suspect. Of all the parts on the system, why would they select the gas key, a small part which historically has had no issues at all aside from fastening it to the carrier and staking it properly (which LMT already did well)? It just doesn't make sense to dick with a gas key of all things, other than to save money on a relatively low stress part where they could "get away" with something cheaper.
It may very well be a non-issue and these new keys may hold up just fine. I'm just not buying the "new and improved" line as opposed to it being purely a cost-saving measure.
Going4Broke
06-12-09, 16:49
Seeing as how the complaints are from people noticing cracking at the staking sites and not failed gas keys, my hunch is that this is much ado about nothing. Having said that, LMTs response is pathetic, at best. If it's such a great improvement why not come out and say "Yes, it's MIM. Would you like a sample to test?"?
So what is pathetic about it. They did a very good job explaining things without divulging proprietary information. Maybe it is MIM and maybe it is not, but for some reason of competitive advantage maybe is why they won't say. I could be wrong, but I thought MIM had the same hardness throughout and that is not how it was described.
Going4Broke
06-12-09, 16:51
I certainly don't want to stifle innovation or claim that it's bad for companies to try new and potentially better materials and methods. It also appears that LMT did some homework and testing on this new part, and I own a complete LMT SBR that runs strong - so I have no complaints generally about the company.
Having said that, I still find this highly suspect. Of all the parts on the system, why would they select the gas key, a small part which historically has had no issues at all aside from fastening it to the carrier and staking it properly (which LMT already did well)? It just doesn't make sense to dick with a gas key of all things, other than to save money on a relatively low stress part where they could "get away" with something cheaper.
It may very well be a non-issue and these new keys may hold up just fine. I'm just not buying the "new and improved" line as opposed to it being purely a cost-saving measure.
Did you read the letter as to why they did it? Just asking because I thought they gave a good reason.:confused:
Did you read the letter as to why they did it? Just asking because I thought they gave a good reason.:confused:
Yes, of course I read it. More than once. In fact I read it yesterday, slept on it, and read it again today.
They never explained why they looked at the gas key, and changing it, in the first place. They also carefully skirted the issue of whether it was MIM and of course didn't address at all how much this change saved them per unit in cost.
I'll reiterate that I don't have any reason to believe the part will fail at a higher rate than other gas keys - I just don't believe their rationale that it's some kind of "improvement."
Going4Broke
06-12-09, 23:56
Yes, of course I read it. More than once. In fact I read it yesterday, slept on it, and read it again today.
They never explained why they looked at the gas key, and changing it, in the first place. They also carefully skirted the issue of whether it was MIM and of course didn't address at all how much this change saved them per unit in cost.
I'll reiterate that I don't have any reason to believe the part will fail at a higher rate than other gas keys - I just don't believe their rationale that it's some kind of "improvement."
Maybe I am wrong, but I understood it to mean that they found that wear and friction on the gas tube and key decreased performance. They said that by heat treating it and a coating decreased this and allowed for better performance so that is why they did it. Not sure the perameters of the performance they are talking about, but this is what I understood it to mean. Either way LMT has never made a second rate product and they stand behind their stuff so I would not worry about it.:)
I've had a MIM keyed LMT BCG for 8 months, noticed the fractures at the staking points, and made an inquiry at that time.
http://m4carbine.net/showthread.php?t=20664
These items are newish but not exactly new so I'm surprised at the level of outrage being expressed at this time. Its mounted in my HD AR, with 5100 rd fired. Have kept an eye on it, and will continue to do so.
The response from LMT confirms most of my thoughts. Until further evidence appears, I will continue to consider LMT as a company that builds first rate AR rifles and parts. I don't begrudge LMT for going to alternate manufacturing processes either to improve a part, decrease unit cost, or to increase productivity.
Check out this key staking method.... (I'm going to post this pic in the other staking threads to get any thoughts.)
http://i210.photobucket.com/albums/bb201/trixiebud/hudson067.jpg?t=1244907206
flyboy1788
06-13-09, 11:13
+1. Has anyone every known LMT to make an inferior product or part?? didn't think so.;)
I GUARANTEE you if this was bushmaster or rock river or one of the other "lesser" companies that tried this carrier key on their bcgs, it would be a big deal and it would be thought of as inferior.
Check out this key staking method.... (I'm going to post this pic in the other staking threads to get any thoughts.)
http://i210.photobucket.com/albums/bb201/trixiebud/hudson067.jpg?t=1244907206
I've seen the "three dot" staking before:
http://i150.photobucket.com/albums/s95/MMcfpd/Young_BC_staked.jpg
But the example you posted might have missed the point a bit.
*****
I received the same reply from LMT regarding the original question and I'm not too concerned at this point.
Maybe I am wrong, but I understood it to mean that they found that wear and friction on the gas tube and key decreased performance. They said that by heat treating it and a coating decreased this and allowed for better performance so that is why they did it. Not sure the perameters of the performance they are talking about, but this is what I understood it to mean.
I'm not really sure what they're talking about, either, given that gas keys and gas tubes don't "wear out" and there isn't an appreciable amount of friction between the gas key and tube, or between the gas key and receiver, to cause any issues with performance or function. There are so many more points of contact that cause much more friction. It just doesn't make sense.
I am willing to bet that they changed the part to be able to get their hands on more of them, more easily, and at a lower cost. I also believe them when they say they tested them with 100K+ rounds of ammo, but I still think they did that just to make sure the cheaper part would hold up - NOT because it is some sort of harder, lower friction improvement that makes he guns more reliable.
I've seen the "three dot" staking before:
But the example you posted might have missed the point a bit.
Yeah. There's a wild one on the key, but when you handle the carrier all if the dots are infact pushing metal against the screw head.
I GUARANTEE you if this was bushmaster or rock river or one of the other "lesser" companies that tried this carrier key on their bcgs, it would be a big deal and it would be thought of as inferior.
Amen.
I'm not really sure what they're talking about, either, given that gas keys and gas tubes don't "wear out" and there isn't an appreciable amount of friction between the gas key and tube, or between the gas key and receiver, to cause any issues with performance or function. There are so many more points of contact that cause much more friction. It just doesn't make sense.
I am willing to bet that they changed the part to be able to get their hands on more of them, more easily, and at a lower cost. I also believe them when they say they tested them with 100K+ rounds of ammo, but I still think they did that just to make sure the cheaper part would hold up - NOT because it is some sort of harder, lower friction improvement that makes he guns more reliable.
Amen.
bigshooter
06-13-09, 13:36
Here is the letter that LMT has issued.
C4
http://www.gandrtactical.com/images/archive/LMT/Gas%20Key%20Study%20Response%20June%202009.pdf
outstanding.
blah blah blah.
I'm not buying LMT BCGs anymore. Folks are right, if it was Bushmaster, RRA, etc, it would be a huge deal.
Bravo BCGs it is.....
It's like trying to defend the Mustang II.
Yeah, but it's a "Mustang"! (See link) Hot!!
http://tinyurl.com/leaqsf
flyboy1788
06-13-09, 16:30
blah blah blah, I'm not buying LMT BCGs anymore. Folks are right, if it was Bushmaster, RRA, etc, it would be a huge deal.
Bravo BCGs it is.....
^^^This. LMT is "fixing" a problem that isnt even there. First, I would rather have the machined steel key with hard chrome lining than this so called "better" version that LMT puts out. second, suppose it actually is better than the version companies have been using since ar-15s/m16s first came out, how many instances of gas tubes or carrier keys wearing out have been recorded. There are a handful of other items that WILL break/ wear out before the afformentioned combo. I think LMT wanted to save costs and increase production, and in order to justify this and maintain their reputation, they have released some test results that show that MIM parts work fine, at least in their testing it did anyways. Maybe it will be fine after all, but I would most definately rather rely on a system that is proven(BCM) than the new LMT carrier keys at least for now.
^^^This. LMT is "fixing" a problem that isnt even there. First, I would rather have the machined steel key with hard chrome lining than this so called "better" version that LMT puts out. second, suppose it actually is better than the version companies have been using since ar-15s/m16s first came out, how many instances of gas tubes or carrier keys wearing out have been recorded.
Two good points....
1. Just look at the LMT "enhanced" bolt assembly... another example of LMT "improving" something... yet no one here would run one of those bolts in one of our guns. and..
2. Tube/key friction is a non issue because a barrel will get replaced way before 100k rounds... thus the gas tube would be replaced too.
flyboy1788
06-13-09, 16:56
2. Tube/key friction is a non issue because a barrel will get replaced way before 100k rounds... thus the gas tube would be replaced too.
EXACTLY. This is also assuming the LMT key actually is "better".
This is actually in the TM and is known as the Field Staking Method. It's on page 173. Though the staking on the furthest screw out isn't that good.
Check out this key staking method.... (I'm going to post this pic in the other staking threads to get any thoughts.)
http://i210.photobucket.com/albums/bb201/trixiebud/hudson067.jpg?t=1244907206
bigshooter
06-13-09, 17:11
Why - so - serious?.
Should I be pissed that LMT is changing their gas keys to save money and/or solve availability issues by using a different design?.
If it is as reliable/durable as they claim, what's the stink about?.
Has there even been a documented failure at this point?.
As far as the "if BM did this they'd be getting savaged", yeah your right, but what's your point?. They get savaged anyway, and rightfuly so 90% of the time.
I'm serious about it because I depend on my guns to protect my life.
I have the "old" LMT bolts and trust those.
If I wasn't serious, I guess I would use Bushmasters, but I want something I can trust, and that *will* work.
Just my .02 (though with inflation, is worth only a penny.) :D
spamsammich
06-13-09, 19:10
None of us "know" if these new carrier keys will fail us. Some have been running them for a while now without even noticing. Are they inferior? Prove it to me, I'll believe it when I see it. I don't have a dog in this fight, but I don't sweat the staking or the key in the least. The last time I checked, the LMT BCG was still $129 bucks, throw on another gas key and your right on par with other "proven" BCGs. Boo frickin hoo. Right now, I don't believe 80% of the people on this site or 99% of TOS will shoot enough rounds for the LMT BCG to fail or come close to it.
If it is as reliable/durable as they claim, what's the stink about?
Because we don't yet know whether their claims will hold true in the long run and, more importantly, their explanation reeks of BS. If they had just said "Yes, it's MIM and we know how to do MIM properly and we have proven through testing that it holds up fine," then there wouldn't be nearly as much of an issue.
Has there even been a documented failure at this point?.
I really doubt it given that they've only been out a few months.
nogoodnamesleft
06-13-09, 19:33
This is actually in the TM and is known as the Field Staking Method. It's on page 173. Though the staking on the furthest screw out isn't that good.
Where does one find the TM or TDP? It's often referenced but only in small, selective bits.
nogoodnamesleft
06-13-09, 19:36
None of us "know" if these new carrier keys will fail us. Some have been running them for a while now without even noticing. Are they inferior? Prove it to me, I'll believe it when I see it. I don't have a dog in this fight, but I don't sweat the staking or the key in the least. The last time I checked, the LMT BCG was still $129 bucks, throw on another gas key and your right on par with other "proven" BCGs. Boo frickin hoo. Right now, I don't believe 80% of the people on this site or 99% of TOS will shoot enough rounds for the LMT BCG to fail or come close to it.
So, I take it you're a Bushmaster fan.
spamsammich
06-13-09, 19:41
So, I take it your a Bushmaster fan.
Thought about buying one right before the '94 ban, but never committed. Now I can find better ways to spend my money. Especially after reading what Iraqgunz has to deal with.
Thomas M-4
06-13-09, 20:17
I'm not really sure what they're talking about, either, given that gas keys and gas tubes don't "wear out" and there isn't an appreciable amount of friction between the gas key and tube, or between the gas key and receiver, to cause any issues with performance or function. There are so many more points of contact that cause much more friction. It just doesn't make sense.
I am willing to bet that they changed the part to be able to get their hands on more of them, more easily, and at a lower cost. I also believe them when they say they tested them with 100K+ rounds of ammo, but I still think they did that just to make sure the cheaper part would hold up - NOT because it is some sort of harder, lower friction improvement that makes he guns more reliable.
My gut feeling is the same and I am a LMT fan boy. Its been tested by LMT for reliability I will take there word for it but at the same time the next LMT build I will be keeping and eye on it and will probable pick up a spare BCM gas key just in case.
Going4Broke
06-13-09, 20:34
None of us "know" if these new carrier keys will fail us. Some have been running them for a while now without even noticing. Are they inferior? Prove it to me, I'll believe it when I see it. I don't have a dog in this fight, but I don't sweat the staking or the key in the least. The last time I checked, the LMT BCG was still $129 bucks, throw on another gas key and your right on par with other "proven" BCGs. Boo frickin hoo. Right now, I don't believe 80% of the people on this site or 99% of TOS will shoot enough rounds for the LMT BCG to fail or come close to it.
Could not agree with you more. I can't believe all the "EXPERTS" here that think they know everything about this and know that it is lesser quality and can't trust it. LMT better hire them as consultants because they know more than them. Guess a 135k round torture test isn't enough to show durability. Name one item LMT has made that has been subpar to anything else. . . . . . . . good luck!
flyboy1788
06-13-09, 20:59
Could not agree with you more. I can't believe all the "EXPERTS" here that think they know everything about this and know that it is lesser quality and can't trust it. LMT better hire them as consultants because they know more than them. Guess a 135k round torture test isn't enough to show durability. Name one item LMT has made that has been subpar to anything else. . . . . . . . good luck!
'a' 135 round torture test, meaning just one test. Congratulations. Come back to me after these carriers have been on the market for a couple YEARS and have been through many carbine courses with the same results... As far as naming one item that LMT makes that is subpar to anything else, that is irrelevant. Just because someone has a good track record doesnt mean they cant start cutting corners, and just because somebody has a lesser track record doesnt mean they cant/ wont ever step it up.
nogoodnamesleft
06-13-09, 21:01
Originally posted by Going4Broke
Name one item LMT has made that has been subpar to anything else. . . . . . . . good luck!
Just asking here as I am no expert -- nor do I have the vaulted TDP/TM to reference -- but would a MIM gas key meet the TDP? Would the military accept the part, thereby making it mil-spec?
MIM is a manufacturing technique which has it's unique issues with part design. How would we know that it's "good to go" and not "just as good"?
If your answer is "time will tell", then I've got this Bushmaster I can sell you.
Going4Broke
06-13-09, 21:47
'a' 135 round torture test, meaning just one test. Congratulations. Come back to me after these carriers have been on the market for a couple YEARS and have been through many carbine courses with the same results... As far as naming one item that LMT makes that is subpar to anything else, that is irrelevant. Just because someone has a good track record doesnt mean they cant start cutting corners, and just because somebody has a lesser track record doesnt mean they cant/ wont ever step it up.
Don't know how many tests, 1 or 100, or the perameters or conditions of said tests.
How is it irrelvant? Say a certain horse has never finished a race lower than second or third place in the 3 years that horse has been racing. You are given a bunch of money to bet on 1 horse and it is an all or nothing bet. Are you going to bet on the horse with the best rack record or a horse that has maybe only won 1 or 2 races in its life? Are you going to buy a car with a track record of having next to zero maintenance issues in its history or go with a car company that has had a sketchy history, but has a new car that looks really pleasing to the eye? I believe track record is everything when making purchasing decisions. Just like why people generally buy from companies like G&R or BCM, they have always had an excellent track record for customer service and quality products. Sorry, I will agree to different opinions, but do not buy the track record theory.
Just asking here as I am no expert -- nor do I have the vaulted TDP/TM to reference -- but would a MIM gas key meet the TDP? Would the military accept the part, thereby making it mil-spec?
MIM is a manufacturing technique which has it's unique issues with part design. How would we know that it's "good to go" and not "just as good"?
If your answer is "time will tell", then I've got this Bushmaster I can sell you.
Can not answer your question, but there is no civilian gun made that is MIL spec anyway. Besides, by definition of MIL spec does not always mean better/best, just means by the military's specification for commanality.
Maybe some have misunderstood me, but I don't care so much about the product as I am bugged by people rushing to judgment thinking they know everything and all the facts on whether it is better or inferior or done for this reason or that. Time will tell, but look at what was done for testing and look at the companies track record. . . . . do people honestly believe a stand up company is willing to risk their reputation on what would amount to be such a miniscule % of their gross income? :rolleyes:
bigshooter
06-13-09, 22:06
'a' 135 thousandround torture test, meaning just one test. Congratulations.
ROFLMAO..
your really digging deep when you blow off a 135,000 round test as not being good enough.
this is getting sad.
flyboy1788
06-13-09, 22:59
ROFLMAO..
your really digging deep when you blow off a 135,000 round test as not being good enough.
this is getting sad.
Sad? Would that be sad if before a company starts selling a product, they only test one gun? And if that one gun happens to pass that one test with no problems, they throw it on the market. No. Most of the time a rock river owner wont have to worry about a carrier key coming loose, but guess what, it happens more to them than to those who stake their carriers properly. Great, one carrier key passed the test. Look, Im not bashing here, everyone might start selling MIM keys before long. It might be the preffered method of manufacture, who knows. They might wind up being more desireable, but for now, it is unproven, and I personally would hesitate to get one until the jury is out on them. I understand that LMT puts out top of the line pieces of equipment, but this move makes me hesitant no matter what their rep is. YMMV
Where does one find the TM or TDP? It's often referenced but only in small, selective bits.
The TDP is not available for public consumption.
bigshooter
06-13-09, 23:27
Sad? Would that be sad if before a company starts selling a product, they only test one gun? And if that one gun happens to pass that one test with no problems, they throw it on the market. No. Most of the time a rock river owner wont have to worry about a carrier key coming loose, but guess what, it happens more to them than to those who stake their carriers properly. Great, one carrier key passed the test. Look, Im not bashing here, everyone might start selling MIM keys before long. It might be the preffered method of manufacture, who knows. They might wind up being more desireable, but for now, it is unproven, and I personally would hesitate to get one until the jury is out on them. I understand that LMT puts out top of the line pieces of equipment, but this move makes me hesitant no matter what their rep is. YMMV
You sir, fail at reading.
May I suggest you go back to the letter and read it again. Feel free to post up when you find the part where they only tested one key in one gun.
flyboy1788
06-13-09, 23:36
You sir, fail at reading.
May I suggest you go back to the letter and read it again. Feel free to post up when you find the part where they only tested one key in one gun.
My mistake, SIR. :rolleyes: I read over it too quickly. So it wasnt one key, it was over 20 or whatever the last page said going by the numbers of the rifles, that is still besides the point. I would like to wait until there are hundreds of something, even thousands, before I trust it. I guess you still dont get the point Im trying to make, you would rather point out the little details and make yourself look witty by calling me out.
If this part turns out to be at all less desirable than the chrome lined key (meaning 2/1000 fail as opposed to 0/1000), then I personally would like to have the one that is least likely to fail. We wont know until there are more of these new MIM keys on the market. I choose to reserve judgement until these have been around for a while rather than put complete faith in a new part best on a small(relatively) test batch of keys. YMMV
You sir, are welcome to disagree with me. BTW, I am done with this discussion, I really dont care to go any further into a discussion about a part that I will not be dealing with any time soon or ever for that matter.
nogoodnamesleft
06-14-09, 07:58
Can not answer your question, but there is no civilian gun made that is MIL spec anyway. Besides, by definition of MIL spec does not always mean better/best, just means by the military's specification for commanality.
I'm not one to drink the Kool-Aid until I know what's in it. I figure it's my money and I would like to have an informed buying decision, but damn if you guys don't make it hard.
The TDP/TM/Mil-spec is usually thrown out here as the minimum standard for having a "good to go" rifle. Anything else, especially "just as good", is a "fail". But I'm finding that some on this site selectively apply the TDP/TM/Mil-spec standard on what appears to be only a brand basis. Unfortunately the standard is not "available for public consumption" (I assume this means proprietary IP of some company) which means I have to ask annoying questions to get information.
Truth is, MIM is a manufacturing technique that produces parts at a lower cost, providing better quality than cast, but not quite as good as the other techniques. There is no other explanation than it is to "cut a corner" -- expand production, reduce cost. Does it meet the TDP and is "good to go" or is it "just as good"? If it doesn't meet the TDP, the minimum standard of acceptable quality, will it still do the job as suggested by LMT's tests? If that is a "yes", then maybe "just as good" really is "good to go" after all. Which implies that Bushmaster is much better than others here have given credit.
I don't care to rehabilitate Bushmaster's reputation here, I'm trying to figure out what would be the best place to spend my hard earned money.
spamsammich
06-14-09, 13:56
If you're really interested in a Bushmaster, PM Iraqgunz and pick his brain about them or talk to Grant, they probably have the most experience with keeping them running and QC issues over the years. I have no business commenting on them because all I run are LMTs and mutts I build for myself.
Cincinnatus
06-14-09, 20:57
Two good points....
1. Just look at the LMT "enhanced" bolt assembly... another example of LMT "improving" something... yet no one here would run one of those bolts in one of our guns. and..
2. Tube/key friction is a non issue because a barrel will get replaced way before 100k rounds... thus the gas tube would be replaced too.
Why would one not want to put an enhanced BCG in one's gun? This is the first negative thing I have heard about the enhanced BCG. :confused:
Nevermind. Found this thread:
https://www.m4carbine.net/showthread.php?t=28409&highlight=enhanced+bolt
Cincinnatus
06-24-09, 22:01
About the idea that a new gas key design would reduce wear on the Upper. Correct me if I'm wrong, but doesn't the gas key rub only against the groove inside the charging handle and not against the upper itself at all?
Even so, LMT's extensive testing reassures me and I will continue to buy their BCGs with confidence.
Anyone know how long LMT has been producing/buying MIM parts?
What kind of experience do they have in this area? Do they know the pitfalls?
What kind of reputation does MIM have compared to forged or billet parts.
I'm not saying these carriers are bad. I'm not saying LMT doesn't have a sterling reputation. This may well be the wave of the future, and soon everyone's BCG will have MIM parts.
With the emphasis placed on 100% reliability by members on this forum, it surprises me that the LMT name makes this new to them, manufacturing method GTG. What flavor is this kool-aid?
MIM is a tricky process. A huge variable is the carrier that the metal powder is mixed with. EVERY manufacturer has tolerances to hold. Resin manufacturers are no different. I've seen different lots of the same resin react differently to fixed parameters in an injection molding press. The tool sure as hell doesn't change anymore than the bricks in the front wall do. Yup, switch different lots of the same resin, and get different results.
Done correctly MIM produces a good part. On a critical part like a carrier key, I'm not going to be the first hog at the trough. If LMT can produce consistent, good parts over the next couple years, I'll believe they have conquered this process. Otherwise, let TOS run this stuff in their Oilys.
Mark15
Anyone know how long LMT has been producing/buying MIM parts?
What kind of experience do they have in this area? Do they know the pitfalls?
What kind of reputation does MIM have compared to forged or billet parts.
I'm not saying these carriers are bad. I'm not saying LMT doesn't have a sterling reputation. This may well be the wave of the future, and soon everyone's BCG will have MIM parts.
With the emphasis placed on 100% reliability by members on this forum, it surprises me that the LMT name makes this new to them, manufacturing method GTG. What flavor is this kool-aid?
MIM is a tricky process. A huge variable is the carrier that the metal powder is mixed with. EVERY manufacturer has tolerances to hold. Resin manufacturers are no different. I've seen different lots of the same resin react differently to fixed parameters in an injection molding press. The tool sure as hell doesn't change anymore than the bricks in the front wall do. Yup, switch different lots of the same resin, and get different results.
Done correctly MIM produces a good part. On a critical part like a carrier key, I'm not going to be the first hog at the trough. If LMT can produce consistent, good parts over the next couple years, I'll believe they have conquered this process. Otherwise, let TOS run this stuff in their Oilys.
Mark15
I believe that these MIM'd gas keys have been out for over a year. To date, we have not encountered or heard of ANYONE having a single issue.
C4
OK Grant. Does that mean that all issues with production have been resolved, and these MIM parts will enjoy the same reliability as the billet parts?
I'm not peeing in anyone's Wheaties. I certainly don't want to wish anyone any bad luck. I do know the issues associated with this process, and understand the pitfalls that can and do occur. I hope it works out for LMT and all of their customers.
Mark15
OK Grant. Does that mean that all issues with production have been resolved, and these MIM parts will enjoy the same reliability as the billet parts?
I'm not peeing in anyone's Wheaties. I certainly don't want to wish anyone any bad luck. I do know the issues associated with this process, and understand the pitfalls that can and do occur. I hope it works out for LMT and all of their customers.
Mark15
I am unaware of any issues with production.
My point is that these gas keys have been around for about a year & no one has had a key break or fall off.
This is all I am saying & nothing more.
C4
Grant, Could this be a situation that no one you know of has had a key break or fall off?
Mark15
Grant, Could this be a situation that no one you know of has had a key break or fall off?
Mark15
Sure, but since I watch all the major AR forums and talk to LMT (who advise me of no issues), I am going to say no.
C4
Well then, your statement holds water.
Mark15
This is quite an interesting topic. Normally, with a technical subject such as this, I would read and try and learn something, but not post a comment. However, two thoughts occurred to me that may be worth noting. Then again, maybe not.
For the record, I have an LMT lower, I am in the market for a BCG for my new upper, and an LMT carrier is (or has been) 1st on my short list of choices.
It does seem a little strange that a company with the reputation for quality that LMT enjoys would pick this part to quietly change. The cost savings can't amount to more than a few cents, perhaps a few dollars, per carrier. I would think LMT would be better off charging a few extra dollars per carrier, and keep it the same, rather than keep the price the same and risk a lower quality product.
Which begs the question - is quality lower? I have no idea, but if it were not, why are some keys cracking? Will the crack propagate? I don't know. Will the carrier fail sooner? I don't know. Is this much ado about nothing? Again, I don't know. I do know that screwing with ones reputation is dangerous. To justify the risk, there better be a BIG payoff, and I don't see one in a few pennies cost reduction.
The other observation is, when S&W went to mim parts for their revolvers, they were widely criticized. While I don't have first-hand experience ( I don't own a S&W with mim parts), I have read on forums just as reputable as this that the mim parts are not as durable, breaking more frequently.
Prior to this thread, I would have bought an LMT carrier without thinking. Now, I'll have to read more and do a little more research.
I seem to remember Bushmaster had a pretty good reputation at one time. They relied on this to carry them. Now, whether it's fair or not, whether it's even deserved or not, they are no longer considered a top tier manufacturer, and it all began with cutting corners to cut costs.
This is quite an interesting topic. Normally, with a technical subject such as this, I would read and try and learn something, but not post a comment. However, two thoughts occurred to me that may be worth noting. Then again, maybe not.
For the record, I have an LMT lower, I am in the market for a BCG for my new upper, and an LMT carrier is (or has been) 1st on my short list of choices.
It does seem a little strange that a company with the reputation for quality that LMT enjoys would pick this part to quietly change. The cost savings can't amount to more than a few cents, perhaps a few dollars, per carrier. I would think LMT would be better off charging a few extra dollars per carrier, and keep it the same, rather than keep the price the same and risk a lower quality product.
Which begs the question - is quality lower? I have no idea, but if it were not, why are some keys cracking? Will the crack propagate? I don't know. Will the carrier fail sooner? I don't know. Is this much ado about nothing? Again, I don't know. I do know that screwing with ones reputation is dangerous. To justify the risk, there better be a BIG payoff, and I don't see one in a few pennies cost reduction.
The other observation is, when S&W went to mim parts for their revolvers, they were widely criticized. While I don't have first-hand experience ( I don't own a S&W with mim parts), I have read on forums just as reputable as this that the mim parts are not as durable, breaking more frequently.
Prior to this thread, I would have bought an LMT carrier without thinking. Now, I'll have to read more and do a little more research.
I seem to remember Bushmaster had a pretty good reputation at one time. They relied on this to carry them. Now, whether it's fair or not, whether it's even deserved or not, they are no longer considered a top tier manufacturer, and it all began with cutting corners to cut costs.
The gas key is one of the harder things to produce in the BCG and is also very expensive (for its size).
With the shortage of BCG's in the market (shortage of gas keys really), I think that LMT went out and tried to find a way to get more gas keys at a cheaper price.
If the gas keys are MIM, it would NOT save them a few "cents", but in fact DOLLARS!!! This is a big savings when you produce as many BCG's as they do.
I also do not believe that LMT tried to "sneak" these gas keys into the system. There is no rule that says a company has to have a press release everytime they change a part.
C4
nogoodnamesleft
06-28-09, 09:11
I also do not believe that LMT tried to "sneak" these gas keys into the system. There is no rule that says a company has to have a press release everytime they change a part.
C4
Agreed, I don't think the word 'sneak' would be appropriate here, but I'm pretty sure they wouldn't want to advertise it either. I can just imagine the tag lines "Our BCGs now come with MIM! Get yours today." or "LMT, now with MIM because Good As is really Good To Go".
The large, multinational company I work for has mandatory ethics and SBC training every year. To help employees determine what is the correct choice for almost any situation, they employ the "headline test", which is how it would look if the choice made were put on the headline of newspapers. This applies not only to individual decisions, but business decisions that affect the company's reputation. That is perfectly apropos here.
BTW, this isn't the only part we're seeing from LMT with MIM. I saw a very good picture of the new LMT charging handle here http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=LMP103 and the latch is MIM. Which, in my opinion, means it's just a matter of time before the other firearms companies do this to their AR platforms -- they just need to let the stigma of using MIM subside.
Heavy Metal
06-28-09, 10:50
Grant,
What kind of coating do these gas keys have?
I did not realize gas keys were so expensive, but they can't amount to that significant a percent of the $130 price tag for which the entire BCG sells. With all the work that goes into the machining and testing of each bolt and carrier, just how much savings are we talking about here?
I also did not mean to imply that LMT "snuck" in the changes in the dead of night, trying to pull a fast one on consumers. They have a reputation for quality and integrity, and I have no reason to doubt this remains the case.
That said, mim parts have a bad reputation. Perhaps not deserved, but most buyers would not choose a mim part over another, especially is cost were the same. Additionally, the "headline test" referred to above is a great idea. If one is not proud of the "improvements" made to a product, and would rather not announce the change, perhaps there is a reason. Finally, cracking of parts is occurring. This can't be a good thing. It may not be a big deal, but then again, it may. I don't know.
I do know (if what I have read here is accurate) that the old carrier worked flawlessly and did not have carrier key fasteners which cracked. The new ones do. As someone else who posts either here or on TOS frequently says - "This is a clue".
theorangecat
06-28-09, 14:17
The large, multinational company I work for has mandatory ethics and SBC training every year. To help employees determine what is the correct choice for almost any situation, they employ the "headline test", which is how it would look if the choice made were put on the headline of newspapers. This applies not only to individual decisions, but business decisions that affect the company's reputation. That is perfectly apropos here.
In the past, I had to attend seminars and training sessions that purported to be ethics training, but which were really presentations designed to ensure that employees did not commit public relations gaffes, and they all featured some variation on the "headline test," although it was not always called that. Some of the decisions that would be made according to those principles might be excellent from the standpoint of eliminating or minimizing damage to the brand and/or management, but be quite out of phase with traditional morality (not to be confused with "ethics," let alone "business ethics"). Nonetheless, they were generally interesting, and sometimes unintentionally quite revealing.
ANYWAY... the question whether to to MIM or not to MIM gas keys will no doubt shake itself out over time, and the market(s) will respond accordingly. Not all that long ago, any firearm with an aluminum receiver and/or synthetic stock was generally considered a cheap piece of crap that very few shooters would actually go out and purchase with their own money. Personally, I would prefer nothing in my firearms be made by MIM that I wouldn't object to if it were made from cast iron, but then again, I'm just getting used to aluminum receivers and synthetic stocks.
nogoodnamesleft
06-28-09, 17:23
In the past, I had to attend seminars and training sessions that purported to be ethics training, but which were really presentations designed to ensure that employees did not commit public relations gaffes, and they all featured some variation on the "headline test," although it was not always called that. Some of the decisions that would be made according to those principles might be excellent from the standpoint of eliminating or minimizing damage to the brand and/or management, but be quite out of phase with traditional morality (not to be confused with "ethics," let alone "business ethics"). Nonetheless, they were generally interesting, and sometimes unintentionally quite revealing.
True enough, the whole point of ethics and SBC training is to not damage the brand or get sued; it has nothing to do with morality. The VP of HR is a former prosecutor in the criminal division of the U.S. Attorney's Office -- it's all about not going to jail, getting sued and brand management.
Personally, I would prefer nothing in my firearms be made by MIM that I wouldn't object to if it were made from cast iron, but then again, I'm just getting used to aluminum receivers and synthetic stocks.
Of course, you probably realize, that MIM is a far cry from cast iron but I can't think of a single thing in a firearm I would want made of cast iron.
Grant,
What kind of coating do these gas keys have?
Don't really know. Could be anything from Melonite to that Diamond coating.
C4
I did not realize gas keys were so expensive, but they can't amount to that significant a percent of the $130 price tag for which the entire BCG sells. With all the work that goes into the machining and testing of each bolt and carrier, just how much savings are we talking about here?
Well, last year, my dealer price on a gas key was over $13.00 dollars! Now LMT is of course making a profit on them, but not all that much. So let us pretend for a moment that they have $8 in a gas key. Take that number times 100,000. Now let's pretend that the the new gas keys cost them $3. They just saved $500,000.00!
Do I believe that the savings are that great? No, I think they are actually saving much more money than that.
I also did not mean to imply that LMT "snuck" in the changes in the dead of night, trying to pull a fast one on consumers. They have a reputation for quality and integrity, and I have no reason to doubt this remains the case.
That said, mim parts have a bad reputation. Perhaps not deserved, but most buyers would not choose a mim part over another, especially is cost were the same. Additionally, the "headline test" referred to above is a great idea. If one is not proud of the "improvements" made to a product, and would rather not announce the change, perhaps there is a reason. Finally, cracking of parts is occurring. This can't be a good thing. It may not be a big deal, but then again, it may. I don't know.
MIM is a bad word (more so in the handgun world though). If done correctly (in non stress areas), I do not think it matters (we shall see though).
The cracking of the TOP of the metal on the key really should not amount to anything.
I do know (if what I have read here is accurate) that the old carrier worked flawlessly and did not have carrier key fasteners which cracked. The new ones do. As someone else who posts either here or on TOS frequently says - "This is a clue".
The old gas keys did work perfectly, but you are missing the bigger picture. Gas keys are NOT AVAILABLE! So here is LMT sitting on 50,000 bolts and carriers with NO GAS KEYS. So they come up with the idea of MIMing the gas key. This way they can get as many as they want and fill their orders.
There are only a handful of companies that make gas keys and they are REALLY quite rare (FYI).
So LMT did not switch gas keys for something to do, but out of necessity.
C4
Of course, the first reaction is to add equipment to make more gas keys. The issue here is amortization. There is a huge push for black rifles now, but how about 3 years from now?
With MIM, there is the cost of the mold, and fixturing. That's it. The molding machine, heat treat equipment, etc. can all be used for other projects in 3 years. With Grant's figure of 500K savings, LMT can pay for the mold completely in 3 months or less.
Cutting parts from the solid is disappearing. Old school gunmaking is disappearing also. Get the good stuff while you can.
Mark15
nogoodnamesleft
06-29-09, 20:55
MIM is a bad word (more so in the handgun world though). If done correctly (in non stress areas), I do not think it matters (we shall see though).
...
The old gas keys did work perfectly, but you are missing the bigger picture. Gas keys are NOT AVAILABLE! So here is LMT sitting on 50,000 bolts and carriers with NO GAS KEYS. So they come up with the idea of MIMing the gas key. This way they can get as many as they want and fill their orders.
...
So LMT did not switch gas keys for something to do, but out of necessity.
C4
This is called "cutting corners" and it is an omen. MIM is a technique that can produce acceptable results, but let's not kid ourselves, it is a "short cut" and that is why it was employed. I believe the gas key is a high-stress part, going from a nominal 14 psi to 20,000+ psi in a msec. LMT's data suggests that their MIM part is capable of meeting that requirement. But, to me, it's even more fascinating because this part's very existence calls into question whether the conventional wisdom of meeting the TDP is really the way to a "good to go" rifle. Or, in other words, is the TDP just so last century?
Whether you think MIM is right or not, it is perfectly clear to me the allure of cost savings will put enormous pressure on all manufacturers to use it where ever they can. And when the stink of MIM has dissipated, even Colt won't resist MIM. Charging handle latches and gas keys are here today, but tomorrow you'll have safety selectors, sears, disconnetors, triggers, hammers, and Extractors. :eek: Maybe the only non-MIM guns you're going to be able to get will come from boutique manufacturers like Noveske and those too small to put up for the capital investment of MIM.
You might want to put those non-MIM guns away in the safe, they're going to become collector's items.
Heavy Metal
06-29-09, 21:07
This is called "cutting corners" and it is an omen. MIM is a technique that can produce acceptable results, but let's not kid ourselves, it is a "short cut" and that is why it was employed. I believe the gas key is a high-stress part, going from a nominal 14 psi to 20,000+ psi in a msec. LMT's data suggests that their MIM part is capable of meeting that requirement. But, to me, it's even more fascinating because this part's very existence calls into question whether the conventional wisdom of meeting the TDP is really the way to a "good to go" rifle. Or, in other words, is the TDP just so last century?
Whether you think MIM is right or not, it is perfectly clear to me the allure of cost savings will put enormous pressure on all manufacturers to use it where ever they can. And when the stink of MIM has dissipated, even Colt won't resist MIM. Charging handle latches and gas keys are here today, but tomorrow you'll have safety selectors, sears, disconnetors, triggers, hammers, and Extractors. :eek: Maybe the only non-MIM guns you're going to be able to get will come from boutique manufacturers like Noveske and those too small to put up for the capital investment of MIM.
You might want to put those non-MIM guns away in the safe, they're going to become collector's items.
The trigger and hammer already are cast. The disconnector is a stamping.
Blankwaffe
06-29-09, 23:27
There are MIM extractors,selectors,ejectors etc. out on the market already and used in the currently available AR's.
LMT's new gas key is probably just a small addition to the list and will soon probably be a major player.
Yeah I'd be willing to bet that the other manufacturers will catch on to the MIM gas keys pretty fast...question is will they use the same protocol as LMT does in assuring that the part is durable and functional enough to be acceptable for long and reliable service.This I seriously doubt.
Here is my long winded ramble on the whole subject.
First of all Im a very big fan of LMT's products,so yeah I drink the coolaid.I also own and like BCM and Noveske products,as well as the lowly thought of Armalites.I hold them all in high regard with each getting credit where credit is due.
I can say that I hate MIM just as bad as the next guy...probably more than average really.Ive had terrible experience with MIM parts on some high end pistols,and have spent a huge amount of time and money bouncing the said pistols back and forth for repair.Thus my hatred for the MIM.I know for a fact that one of the major pistol manufacturers is having major MIM issues.Rather than change the manufacturing process they are going to spend a huge chunk of change on x-ray equipement.So the MIM process must be faster,less labor involved and cheaper in materials.So I don't see any of the manufacturers going back to the old ways.Heck more and more of the parts are being made from polymers anyway...some rather critical like frames,mag catches etc..
In LMT's case,at least they thoroughly test the parts/gas keys in live fire,and destructive testing so Im told.And I bet it was far worse than what the majority of users will ever subject their weapon too.Considering LMT's past record in doing such thorough tests,I have to say I have complete confidence in their findings and decision even though I might not like it.
All I can say for a fact,is I have one of the new gas keys(with cracked stakes) that came on a LMT BCG which I purchased from Grant last fall.The BCG is in a Armalite M15A4 20" upper and has close to 2,700 rounds on it so far.I have seen no issues with the cracked stakes other than being somewhat sharp(cut me),which I dressed down with a diamond file and wet hone.The keys are very hard which is probably why the stakes cracked and why they can probably get away with not chrome lining.With the limited experience with the one single MIM gas key,Im confident in the performance of the one I have.
Regardless,gas keys and gas tubes can be wear items and will need to be replaced eventually if you shoot enough.If the rifle is not assembled correctly then you may have to replace them sooner than later.
So to me the MIM gas key is not confidence inspiring but is in the end has shown to be very functional.
I generally keep at least one spare BCG on hand at all times just in case I do have a failure of any sort related to the BCG.So its even less of an issue in that regard.I also have spare parts to rebuild what I have at least twice.Not to mention I have several complete AR's.
As I said previously if I do see an issue with LMT's new gas keys I will send it back to LMT.My past experience with LMT has been that they are very quick to take care of any issues and show great concern in that regard.So I have very little concern about the products I buy from them.
Lastly,who actually knows what metal is used in the majority of gas keys that are on the market,much less the manufacturing process used in forming the part.I can say for a fact that most of the "lower tier" manufacturers use cheap ars,undersized and brittle YFS screws that I would not trust on a light fixture muchless a gas key.
Then we have the gas tubes which are subjected to even higher pressures than the gas key initially.Who actually knows what material or manufacturing process is used in the production of these parts.
Have the majority of such parts been tested for the psi they are subjected too?
I don't know,but I doubt most are tested at all.
Not to mention the stamped roll pin that holds the gas tube in the gas block or FSB.
Heck I'd say some of the gas blocks and FSB's could be questionable as well.Some are made of aluminum.Not to mention such items as fire control parts,and most concerning to me is the actual bolt and carrier that is so critical and stressed.
So if we are going to worry about the LMT gas keys and go so deep into the subject I guess we need to take a look at other parts as well.
As Heavymetal pointed out the disco's are stamped sheet metal for the most part.Key word is sheet metal.Most of the CH latches are stamped aluminum.Who knows what grade of sheetmetal or aluminum is used in such stamping and how well they are heat treated etc..
Then the weakest link in the system...ammunition.Most folks shoot the cheapest crap they can find.But even the best made ammo can fail at a moments notice.
So IMHO,if the LMT MIM gas key is enough to sway someone from buying one of their BCG's,then I say go buy the BCM or Colt.
Lord knows LMT cant keep the market supplied with enough BCG's as it is.So less pressure by the lose of a few sales might help availability for those of us who want to buy the LMT products.
And yeah,if you want a specialized product rather than a mass produced weapon,BCM and Noveske are sure excellent choices to choose from.
Paul at BCM has a very fine eye for detail and his products show it.
I can say for a fact that the Noveske upper I have is an absolute work of art.Probably one of the finest made and finished uppers Ive seen to date.The Noveske barrels are freakin outstanding.
So yeah,the TDP maybe the base for a quality weapon,but you can do better but you have to willing to pay for it too.
If your concerned about the reliability of your primary weapon in a defense situation,then buy the best quality you can afford and test your gear.Keep an eye on the wear items through proper PM and replace as needed.
And carry a quality secondary weapon and practice the transition in case of a failure of the primary.
Otherwise its a gamble in any respect.
Thats my opinion anyway.
This is called "cutting corners" and it is an omen. MIM is a technique that can produce acceptable results, but let's not kid ourselves, it is a "short cut" and that is why it was employed. I believe the gas key is a high-stress part, going from a nominal 14 psi to 20,000+ psi in a msec. LMT's data suggests that their MIM part is capable of meeting that requirement. But, to me, it's even more fascinating because this part's very existence calls into question whether the conventional wisdom of meeting the TDP is really the way to a "good to go" rifle. Or, in other words, is the TDP just so last century?
I do not look at it as "cutting corners" as much as NECESSITY. Is it cheaper? Sure it. Can they get more BCG's out to the public? Sure can.
The gas key is really not as high a stress point as you think. Even with the cheaper, NONE heat treated gas keys that are commonly used throughout the industry never break. What does break is the screws that hold the gas keys on.
The TDP should NEVER be viewed as a "cutting edge." There are many ways to improve upon the TDP. I am not saying that going MIM on the gas keys is one of them though.
Whether you think MIM is right or not, it is perfectly clear to me the allure of cost savings will put enormous pressure on all manufacturers to use it where ever they can. And when the stink of MIM has dissipated, even Colt won't resist MIM. Charging handle latches and gas keys are here today, but tomorrow you'll have safety selectors, sears, disconnetors, triggers, hammers, and Extractors. :eek: Maybe the only non-MIM guns you're going to be able to get will come from boutique manufacturers like Noveske and those too small to put up for the capital investment of MIM.
As a business owner, being able to get products out the door and save money while doing it is VERY important. This is how we stay in business and feed our families.
C4
Resurrecting an old thread here...:rolleyes:
My brother-in-law has been the QA/QC lab manager for a local MIM parts manufacturer. They MIM parts for very large US weapon manufacturers, as well as for foreign allied military forces.
It all boils down to the quality control requested by the customer.
Cheap power tool manufacturers will be a lot more lax than a company like LMT.
Profit is good, but the cost and bad publicity of a recall would be a disaster for a "small" weapons manufacturer with military contracts.
Now that this has been resurrected...any reported failures of LMT gas keys?
Now that this has been resurrected...any reported failures of LMT gas keys?
Nope.
I was well aware of the MIM controversy when people proceeded to freak out about a year ago, and beat my LMT 14.5" hoping to cause a failure. After almost a year of monthly tactical rifle matches (200+ rounds), the occasional weekly indoor rifle match (60 rounds) and a Magpul Carbine 2 class (800 rounds suppressed, remaining 1200 without can) i see no problems with my MIM gas key.
Mall_Ninja
07-20-13, 02:59
Don't really know. Could be anything from Melonite to that Diamond coating.
C4
Figured I would answer this since it wasnt known at the time. As of a few hours ago, by direct word of mouth from LMT, its "nitrided", so actually harder than chrome...
Since im resurrecting this zombie thread and I now own one of these LMT BCG's I would like to note that mine has no such "MIM" dimple on the top of the key nor any cracks on the staking. So either they stopped using MIM or they got smart and added machining to remove the evidence of such:
http://i112.photobucket.com/albums/n169/JoeDaddy_05/IMG_20130720_244100_236_zpsd374e778.jpg
This one is a few days old from BCM, I would have bought more but only one per customer... :mad:
Would buy more if given the chance, since it appears no one has had any issues?
3 years enough time yet?
Blankwaffe
07-20-13, 23:29
Still no problem with the LMT MIM gas keys I mentioned previously. I've run the devil out of the LMT BCG's and have more than proven to be robust,including the cracked staking. So I remain a happy camper.
Mall_Ninja
07-21-13, 00:33
Still no problem with the LMT MIM gas keys I mentioned previously. I've run the devil out of the LMT BCG's and have more than proven to be robust,including the cracked staking. So I remain a happy camper.
So you have had no crack propagation nor any pieces break loose?
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