View Full Version : Carrier tilt in piston guns Fact of myth
Fact
Ok gents this is a confirmation that carrier tilt does in fact exist . This is my buffer tube with over 10k worth of rounds through it with a piston conversion (LWRC with the enhanced BCG) keep in mind I run my guns hard while preforming the required maintenance. There are solutions from companies like PWS that offer a long-stroke piston upper and a tube for existing uppers. This could cause a world of fail in the right instances. The wear was significant enough to “eject” the whole buffer retaining detent and spring. Rob-s jinxed my shit for realz.
http://i1223.photobucket.com/albums/dd507/photosmith2/P1030450.jpg
http://i1223.photobucket.com/albums/dd507/photosmith2/P1030451.jpg
http://i1223.photobucket.com/albums/dd507/photosmith2/P1030452.jpg
http://i1223.photobucket.com/albums/dd507/photosmith2/P1030453.jpg
http://i1223.photobucket.com/albums/dd507/photosmith2/P1030454.jpg
http://i1223.photobucket.com/albums/dd507/photosmith2/P1030451.jpg
http://i1223.photobucket.com/albums/dd507/photosmith2/P1030450.jpg
DeltaSierra
08-19-11, 17:09
I wish I had pictures (I sold the rifle just before I found this site...) of the piston operated rifle that I had, but after about 500 rounds, the carrier had chewed a pretty good sized chunk out of the upper receiver (oddly enough, it didn't do any damage to the buffer tube.)
Needless to say, I won't be buying another piston gun....Ever...
morbidbattlecry
08-19-11, 17:12
Wow that's looking pretty good for 10k rounds. I've always been worried about the stresses placed on the bolt and lugs more then the buffer tube.
Paraclete comes
08-19-11, 17:34
Im kinda bummed out to see this, considering I just got a LMT MRP upper. I hope and pray I do not run into this issue, anyone see this in a LMT upper? To try and prevent this I also got a spikes solid buffer, any other suggestions
Hispeedal2
08-19-11, 17:41
Thanks for posting this with a round count. Early on, before the "fixes", carrier tilt seemed to be an issue. Now, with the "fixes", some raved that carrier tilt was a non-issue. It appears, in at least this one example, that the "fixes" just prolong use a bit.
I was contemplating getting a piston kit to experiment with, but I think I will stick with DI on the ARs and pull the SCAR out for piston fun.
Have an AA in an upper. No extra decernable wear. Coming up to 6000 rounds. Standard wear marks. I really don't understand the hype, positive or negative.
My experience is all I can go by. But the input from everyone here(who I think are most are extremely knowledgeable) say it's a rabbit hole at best.
Only thing is though, the gun not designed around the operating system. Fail could be right around the corner.
Thomas M-4
08-19-11, 17:42
Im kinda bummed out to see this, considering I just got a LMT MRP upper. I hope and pray I do not run into this issue, anyone see this in a LMT upper? To try and prevent this I also got a spikes solid buffer, any other suggestions
You are in luck since you have the LMT MRP you can just convert it back to DI.
Why does it look like your carrier key was contacting the lower?
Why does it look like your carrier key was contacting the lower?
Probably because it was...
DDoc, you may want to measure / check the bumper on the buffer for wear or damage after seeing that.
SomeOtherGuy
08-19-11, 18:19
Im kinda bummed out to see this, considering I just got a LMT MRP upper. I hope and pray I do not run into this issue, anyone see this in a LMT upper? To try and prevent this I also got a spikes solid buffer, any other suggestions
Easy, convert your MRP to DI using LMT factory parts and sell the piston parts! (As someone already noted)
The MRP in DI runs fine with the stock carbine buffer - at least, mine does. It would probably run fine with an H or H2 as well, but I figure that I can trust LMT's judgment given all the engineering in that model. (I run H or H2 in most other 16" midlengths.)
The_War_Wagon
08-19-11, 19:10
Can't find a pic of my POF Gen.III buffer tube, but it was starting to erode after 500 rounds as well. I'd JUST put a PWS enhanced tube on it, and was ABOUT to order one of Seth's enhanced buffers, when I ended up selling it to a boy who REALLY wanted it!
I am dis-inclined toward owning another 16" piston rifle, that's for sure.
Probably because it was...
DDoc, you may want to measure / check the bumper on the buffer for wear or damage after seeing that.
Long story short, It was from a VERY hot load.......
Really some piston honestly never experience this, my friends pof had (zero) wear in the buffer tube. Buffer tubes are cheap enough.
Fact
Ok gents this is a confirmation that carrier tilt does in fact exist . This is my buffer tube with over 10k worth of rounds through it with a piston conversion (LWRC with the enhanced BCG) keep in mind I run my guns hard while preforming the required maintenance. There are solutions from companies like PWS that offer a long-stroke piston upper and a tube for existing uppers. This could cause a world of fail in the right instances. The wear was significant enough to “eject” the whole buffer retaining detent and spring. Rob-s jinxed my shit for realz.
"Eject" is as in cause a firing malfunction, or when you separated the upper and lower?
Wear on the receiver extension is insignificant. That is not what I would be concerned about. I would be more concerned that the carrier does in fact tilt AT ALL in an AR, regardless of whether or not it's dragging or scraping on the receiver extension.
It's not the receiver extension you should be worried about with a piston AR, it's the bolt.
It's for very good reasons that most, if not all, piston operated guns have rails in the receiver to guide the travel of the carrier and bolt, as well as guide rods to ensure they travel on that path. Take a look at an AR's upper receiver on the other hand and you will notice that there is nothing like that present.
It baffles me that the idiots that call themselves "engineers" at *any* company that makes piston ARs can devise a different gas system for an AR, but not a single one of the monkeys has thought of something so simple as developing or altering an upper receiver with guide rails in it to completely eliminate this known and widespread problem of carrier tilt that shears bolt lugs and scrapes up receiver extensions.
Then again, I would not expect much intelligence or thought from the kinds of people who think developing pistons for ARs is a good idea to begin with. :confused:
Paraclete comes
08-19-11, 23:04
Thanks for the input guys, Ill look into whatever parts I need to convert it into a DI gun.
JR TACTICAL
08-20-11, 02:44
Wow that's looking pretty good for 10k rounds. I've always been worried about the stresses placed on the bolt and lugs more then the buffer tube.
I agree, at least it wore out the buffer tube and ejected the retainer insted of cracking the lower where the hole for retainer is. I have seen that happen 2 times on piston driven gun( I wish I would have snapped some pics of those lowers)
all that's old is new again. the original DI design used convex and concave mating surfaces on the carrier and buffer.;)
justin_247
08-20-11, 11:44
It baffles me that the idiots that call themselves "engineers" at *any* company that makes piston ARs can devise a different gas system for an AR, but not a single one of the monkeys has thought of something so simple as developing or altering an upper receiver with guide rails in it to completely eliminate this known and widespread problem of carrier tilt that shears bolt lugs and scrapes up receiver extensions.
Then again, I would not expect much intelligence or thought from the kinds of people who think developing pistons for ARs is a good idea to begin with. :confused:
Amen. The problem with "converting" a DI system to a piston system is that the carrier and buffer were not designed to be attached to a piston. To truly have a good piston upper receiver, the entire carrier and buffer system must be re-engineered.
Long story short, It was from a VERY hot load.......
I asked the question that way to see if there was a known event or if it could be contributing to the other issue.
there is something seriously wrong with this weapon and carrier tilt is the least of the problems
wolf_walker
08-21-11, 00:17
You know, I don't dispute the folly of converting a DI gun to piston with as little as adding a piston and a solid surface in place of the gas key. But mechanically I think there is more going on in some guns than others when you have failures like this part of the time, and then no problems at all in just as many if not more others with equivalent usag.
I think there are contributing factors in extreme cases like this, but I don't know what they are.
isn't this what the seth harness buffer was made for?
Long story short, It was from a VERY hot load.......
No chance...
The nature of the tilt is usually no big deal but I have found an upper that it is a problem with. It removed the entire opening of the mouth on the extension tube and was just intermittent with problems. It would wierdly do 149 round dumps repeatedly. Then it just got worse.
*To see if you could be having a tilt issue, take your upper only, push up on the area near the bolt like the magazine does, pull down on the rear of the carrier and cycle the carrier, if you feel it is hard to unlock compared to normally cycling the carrier you may benefit from this mod.
The TDP for the AR calls for a high tolerance near the chamber and it can be pretty far out near the rear of the receiver. Manufacturers have tightened the tolerances between carrier and bore so the tilt isn't as bad. The mass production of the TDP for the DI system makes it difficult, I think, for an all our replacement piston upper that has the added meat on the bottom rear of the carrier because it will cause a bind in certain limits of the tdp in the extension tube.
So I have really liked the looks of those anti tilt buffers. So I made one and it seems to have really helped out my situation I had with the tilting badly upper.
Here is what you need.
buffer, I used a H2
.201 drill bit
1/4-20 tap
.188 thick piece of aluminum about 5/8" square or round
1/4-20 button head cap screw
a milling machine-i know this makes it right out of the DIY but there are a few ways this could be done I just chose to mill it.
Step 1.take apart the H2 buffer,
Step 2. Make the round slug that fits very snugly into the rear of your carrier, should be about .62” in diameter but it may vary and you want a very good fit, in the step you are making the round you also put a .260 hole through the center, you can make this larger as this is for clearance and not a locator, it just needs to be larger than the o.d. of the threads and any offsets incurred. Once you have a piece with a hole in the center and a good fit with the carrier you are ready to move to the buffer head modifications.
Step 2. Find center of the buffer head,
Step 3 drill with .201 drill through the buffer head, you need to have the tapped hole as close to center as you can get it but it is not as important as the cylinder location the slug you made will go inside.
Step 4. You will need to mill a .04” deep round hole into the head of the buffer about the exact size of the slug. This needs to be concentric with the buffer as best as possible. If you do this in the same operation of the tapped hole, check for concentricity after the pilot, make the shift, then do the milling.
(This could be done differently, for example no need for milling if you get a shouldered screw, like a ¼-20 screw with a .25 shoulder on it, then you would nail your drilling and tapping on the buffer, and the hole through the slug should be roughly .251 to have a tight fit with the shouldered screw. )
Sneak up on your targets, the slug can be converted from its slug to its ideal shape very easily by holding it with a 1/4-20 screw, chucking the screw in a drill, turning it on and using a file as a turning tool to make the additional geometry. The taper on the slug really helps with installing the upper.
Look at the print and see if you can make the angled geometry to the slug, do not alter the diameter near the base, (I had to edge break the base to get a good snug fit into the buffer pocket)
Step 4. tap through the buffer head now.
Step 5. After making sure all the fits are good, screw the cap screw through the slug into the buffer. Look into the buffer and see how much is protruding. Keep taking apart and sanding the screw thread end until it is flush with the inside surface on the buffer. Take the cap screw and take a pair of pliars to screw the theads up just a little bit(this is assuming it is very easy to thread in and out after tapping) and apply red anti-seize to the theads. Now clean all the buffer internals, coat with a dry film lube if you have it(fine graphite), oils work as well.
Step 6. Install and check the action, the upper and won’t come apart with just removing the rear pin but that is nothing to complain about. When installing, rock the rear into the buffer while the front pin holes get aligned. Then install both pins and cycle. I can install and uninstall my upper whose pins are pretty free in just seconds. Any complaints about the upper-lower disassembly are overcome when you see how easy it is.
http://img88.imageshack.us/img88/3559/hpim0977c.jpg
http://img31.imageshack.us/img31/7669/antltcap.jpg
http://www.youtube.com/watch?v=Q94E55-TkKU
http://www.youtube.com/watch?v=N2MPP6dR0gg
Excellent post!!!! Many who are willing would benefit.
Underwhere
08-25-11, 20:42
Very interesting.
I have an AA rifle (I actually have a few).
I don't have 10k through it yet. I think I have around 3000-3500 and I literally don't see anything at all near the buffer tube area. Unless something changes I wouldn't expect to experience the extreme carrier tilt shown in the pictures.
HuldraArms
08-26-11, 10:25
Not plugging our product, just want to participate and contribute to the discussion. We put 4,844 rounds (so far) through our piston operated Huldra Mark IV 5.45 carbine; Not a scratch on the receiver extension. It actually surprised me a little. With my DI guns there usually is a little cosmetic wear at that point. With our Adams Arms system, we haven’t seen any of the fabled carrier tilt that exist on other piston guns.
Stewart Mills
Huldra Arms
PS: We are shooting the 5.45 to keep expenses down. When rapid firing and doing drills for the sake of round count it is hard to waste good ammo. We figure it makes our testing more strenuous, using corrosive Russian mil surp ammo, if it can hold up to that, 5.56 isn’t a problem. Also, after 4,844 rounds I have upgraded respect for the 5.45 round. It’s the real deal, for not a lot of money. Our 5.45s are selling, especially the uppers.
9508
no offense but you haven't solved anything its just that your upper is lining up well with your lower. The whole reason why you see it here and there and not everywhere is because of the TDP. The location of the bore near the barrel extension is quite critical while allowing a cone like location of the rear.
You have to be doing large numbers in all kinds of conditions, hot ammo/ suppressed/ oversized old ports to even see it sometimes. I have the same mfg uppers and an a common lower and the difference is amazing. Not to mention if I switched lowers into the mix.
Do you not have a system that takes an op-rod and hits the top of the carrer while a round is in the chamber and if you were pivoting over the top lugs your moment arm would be about a 1/4 of an inch. What do you have that is cancelling this moment? Moment=oprod force X moment arm. A nice fit between carrier and id of receiver is a receiver bore that doesn't allow that moment to creat much of a downward movement(nice fit, or even a drill walking in the upward direction instead of the downward) of the rear of the carrier and into the tube it goes.
If I were a piston mfg I would work on just having a kit with a antitilt buffer solution incorporated and......
Why doesn't anyone set up a broach operation so the piston carriers have the full guide rails like the DI system. When you do get in the situation of looking at the full TDP you will see some piston guns that really seem to break through the anodizing early and the full contact rails on the carrier would really help. Hell you could just take it after the lather operation when you have this huge damn ring on the carrier, stand it on the end and edm in the profile without even making a broach. Slow I know but all that 4 axis milling on the carrier isn't exactly fast.
Bad Medicine
08-26-11, 14:50
Has anyone seen this issue with PWS? I haven't and I have about 2500 rounds through my MK116.
Ive never experienced this with my piston gun (LWRC 6.8) Even if I did, Id shoot it until the buffer tube was worn through then Id replace it, 5 minute job.
Long stroke systems are definitely going to be a different ball game compared to short stroke systems, On a long stroke the moment is absorbed slightly by the connection of the op rod to the carrier, for example if it was the same as the short stroke style systems but the op rod was a rigid attachment to the carrier, at that attachment point it would fight the moment aforementioned, so the attachment point would experience rotational stress. Where the short strokes just experience a shear load on the lug.
If it isn't a rigid attachment but has a dog leg down into the carrier then the moment arms are shifted and the guide is pushed up on if it were where they are on an AR.
I never cared about the tube at all and that was my attitude, until I would get a random wierd ejection, usually all my brass was around 3 o'clock then after lots of shooting one would go to the rear around 5, then I would get a short stroke like jam. This would only happen during serious full auto abuse of bursts more than 90 rounds of really hot brass.
It is just kinematics and is true for all of them but only shows its head sometimes. That is why I think a system must take control of this for a full reliable system across all the uppers/lowers/ammo/and all the other stuff. If you're making all your stuff, upper and lower, then you can control it by controlling the mfg tolerances.
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