View Full Version : Which H buffer for a 20" barrel with collapsible stock?
I'm converting a 20" length A2 stocked rifle to a carbine with an LMT sopmod collapsible stock. I was wondering which buffer would be best. I'm a slow shooting precision guy with my AR's at the range, and so anything that tames it while still keeping it working reliable is preferred.
Bravo Company offers an H, H2 and H3. Spikes offers an ST-T2 4.3 oz buffer. Slash's "Heavy Buffers" in Ohio offers an H2 in 4.6 or an H3 in 5.4
You need to get a carbine buffer tube and use the carbine buffer.
Any of the various (top 3 pics) carbine buffers should work (yes, it's a stolen picture).
http://i813.photobucket.com/albums/zz55/ma96782/buffer-construction.jpg
What works BEST?
That's the $64,000 question.
Aloha, Mark
PS...........I'd imagine that the weight of the bullet has a lot to do with it. Issac Newton and all that.
You need to get a carbine buffer tube and use the carbine buffer.
I already have the LMT carbine tube along with my LMT collapsible stock. But thanks for the input; now I know that I need a carbine buffer too.
Would somebody please elaborate which buffer mentioned in my opening post would work best?
What works BEST?
That's the $64,000 question.
Aloha, Mark
PS...........I'd imagine that the weight of the bullet has a lot to do with it. Issac Newton and all that.
I would imagine that using a 20" barrel has some kind of effect on the time and pressure with which the bullet passes over the gas port.....and dictates the difference which would work best for my purposes.
I don't mind choosing a buffer that provides less wear and tear on the rifle too.....as long as it works reliably.
SirPeasant
03-25-11, 00:20
I think that most folks use too light a buffer - I have a 16" barrel with a MID-length gas system and use an H3 buffer which does not short cycle even with .223 ammo. Shoots so soft - like a .22 rifle.
Try an H3 buffer and IF it short cycles then go to an H2.
Without a doubt if I was running a rifle length gas system, I would use a Vltor A5 system. It duplicates the rifle buffer system, even using a rifle spring, but has a collapsable stock.
I would imagine that using a 20" barrel has some kind of effect on the time and pressure with which the bullet passes over the gas port.....and dictates the difference which would work best for my purposes.
I don't mind choosing a buffer that provides less wear and tear on the rifle too.....as long as it works reliably.
Less pressure in a rifle length system pushing the bolt back. A regular carbine buffer will be more reliable. If you want softer shooting you can gradually increase weight but I know for a fact that Tula will not cycle reliably with an H3 and a rifle length system. It seriously depends on ammo.
Edit: and no matter what happens, dont stick a rifle buffer in a carbine tube. -.-
Without a doubt if I was running a rifle length gas system, I would use a Vltor A5 system. It duplicates the rifle buffer system, even using a rifle spring, but has a collapsable stock.
The barrel is a 1-7 twist, firing stout loads of 77 grain Sierra hand loads.
I already have the LMT SOPMOD (complete with tube) and will not be switching to a Vltor or anything else.
That was my recommendation as well.
Without a doubt if I was running a rifle length gas system, I would use a Vltor A5 system. It duplicates the rifle buffer system, even using a rifle spring, but has a collapsable stock.
After alot of experimentation on my LMT carbine lower/tube, I am running my 20" rifle with an H buffer. Soft and reliable even with Wolf.
That was my recommendation as well.
Beat me to it as well.
+A5
Soft shooting 20 inch with rifle gas....I should imagine a basic carbine buffer will be completely fine. As always, for optimal, YMMV due to differing factors with different barrels, such as gas port size etc.
After alot of experimentation on my LMT carbine lower/tube, I am running my 20" rifle with an H buffer. Soft and reliable even with Wolf.
Perhaps, I didn't provide enough info? ....like that it's mostly a stock RR A4 NM rifle. or....I'm not sure if some folks just prefer to ignore that I said I already have the complete LMT SOPMOD collapsible stock, and I am shooting 77 grain bullets.
After reading all the input, it seems KSA464 and Sirpleasant seem to think an H or H2 will work for my purposes.
Thanks for the input gentlemen. My only decision now is between the H or H2 buffer.
H3... rifles barrels kick out a lot of gas, and were designed for use with a 5.5oz buffer. you'll have best results with the heaviest buffer you can find.
i have no experience with the vltor A5 system, but from what i hear, and what i know about vltor products, it's probably the best option for you.
H3... rifles barrels kick out a lot of gas, and were designed for use with a 5.5oz buffer. you'll have best results with the heaviest buffer you can find.
It's not an apples to apples comparison to just look at the weight. The spring cycle is different. A rifle springs at rest tension is lower than a carbine spring.
This is why a carbine that runs on an H buffer can also run great on a rifle buffer and spring.
It's not an apples to apples comparison to just look at the weight. The spring cycle is different. A rifle springs at rest tension is lower than a carbine spring.
This is why a carbine that runs on an H buffer can also run great on a rifle buffer and spring.
its not apples to apples, but it's pretty close. the carbine spring is a little stiffer, but that's to compensate for being shorter. C7A2s use H3s, as i recall.
Perhaps the H3 is optimal, but the whole physics of the rifle buffer system are completely different. It's not as simple as a little stiffer spring. It's a completely different spring cycle.
Two completely different spring lengths are compressing the exact same amount. This is what makes the A5 such a game changer.
You get the rifle spring cycle on a sliding stock.
Cincinnatus
03-25-11, 12:11
OP, are you also having the barrel cut down? you say you are making this a "carbine," and you never clarified whether or not you were simply switching to a carbine stock or also cutting down the barrel.
OP, are you also having the barrel cut down? you say you are making this a "carbine," and you never clarified whether or not you were simply switching to a carbine stock or also cutting down the barrel.
I'm keeping everthing the same on this RRA NM rifle, and intend to keep firing stout loads of 77gr bullets. I simply want to take the RRA A2 fixed stock off of this rifle, and put the LMT SOPMOD stock and tube on it.
This is really not such a rare and terribly unusual configuration. Here is the Colt Canada version of it:
http://i25.photobucket.com/albums/c54/hobbyguy/800px--1.jpg
I'm sure before the Vltor A5 came along, this configuration had worked just fine. I'm just trying to determine which buffer will operate reliably while preventing a rifle length barrel and gas sytem from causing excess battering. I'm leaning with the H2 buffer at this point.
And please guys, can you just accept it that.....I'M NOT DUMPING MY BRAND NEW SOPMOD stock and tube. If I hear "Vltor" one more time...:suicide2:
that'd be a C7A2... and it's got an H3 in it.
And please guys, can you just accept it that.....I'M NOT DUMPING MY BRAND NEW SOPMOD stock and tube. If I hear "Vltor" one more time...:suicide2:
VLTOR VLTOR VLTOR!!!!
You can put the Sopmod on the Vltor Tube, City Slicker!!
Interesting that the brass flies forward on that rifle with the Bean stock.
:D
Hmm. I'll have to look into the H3 for my 20" w/UBR stock. Mine currently has just an H buffer and shoots good and soft with the 55 gr load I tested it with, but have fired too few rounds to claim anything.
Thanks bkb0000 for adding that
that'd be a C7A2... and it's got an H3 in it.
Hmmmm......just when I was settling on an H2, you've got me wondering. You seem know something more then folks like this other one-track minded guy who goes to sleep with a Vltor butt at night.
Ok....if the Canadian C7A2 operates fine on the lighter stuff.....I wonder now if I should use an H3 for the steady diet of 77 grain loads. It makes makes sense ....... assuming that you're correct that the C7A2 does use the H3 buffer. Just curious; how do you know this about a Canadian AR15 variant?
The issue now is just trying to make the right choice from the start and avoid tossing about $50 bucks on the wrong buffer and the shipping charges.
Hmmmm......just when I was settling on an H2, you've got me wondering. You seem know something more then folks like this other one-track minded guy who goes to sleep with a Vltor butt at night.
The irony is rich. You want to hear what you want to hear... and that's cool.
You paid for a friggin SOPMOD and the $35 you might spend on an extra buffer is worth losing sleep over? Good luck with your full sized Carbean.
By the way... if running a carbine buffer system on a rifle was such a good idea...
WHY did the Marine Corps research the A5? Why didn't they just put a ****ing carbine stock on their A4s????
I WONDER? :eek:
well searching through old threads here on M4C, the consensus seems to be that the C7A2 actually comes standard with an H2, not H3. i'm almost positive i remember reading a TM or similar technical document that said it uses an H3, but i wouldn't want to steer you wrong just because i think something.
either way... the weapon will likely run with whatever you put in it. people have run billions of rounds with carbine lower/rifle upper guns with every buffer weight made, and probably some they don't make, and had success. but you're going to increase the ODDS of having less troubles with the "correct" weight.
Canadians use the H2 buffer. Statistically the C7 MRBF is between the M4 and the M16, though you're talking shifts so small it took a large sample to find the trend.
Ok....if the Canadian C7A2 operates fine on the lighter stuff.....I wonder now if I should use an H3 for the steady diet of 77 grain loads.
bullet weight shouldn't have anything to do with it. 77gr loads are generally lower pressure, because they're generally loaded to SAAMI spec, rather than NATO. in fact, it's pretty hard to find 5.56 pressure ammo in anything heavier than 62gr m855... so if anything, if you're shooting a lot of 77gr ammo and you have to chose between buffer weights, the lighter buffer will likely be the choice to go with.
I don't think anyone can give you the answer you are looking for, not seriously anyway. What works in our rifles and our loads may nit work for you at all. My 18" SPR clone with a rifle length system runs fine with a standard carbine buffer in a UBR and carbine spring. Unfortunately, The only reliable answer to your question is going to be experimentation to see what works with your rifle and ammo.
I hate to break this to you, but you are going to have to try it out and see. Unless you can contact RRA and find out what gas size their ports are.
My guess is that it is overgassed like many others.
I'm keeping everthing the same on this RRA NM rifle, and intend to keep firing stout loads of 77gr bullets. I simply want to take the RRA A2 fixed stock off of this rifle, and put the LMT SOPMOD stock and tube on it.
This is really not such a rare and terribly unusual configuration. Here is the Colt Canada version of it:
http://i25.photobucket.com/albums/c54/hobbyguy/800px--1.jpg
I'm sure before the Vltor A5 came along, this configuration had worked just fine. I'm just trying to determine which buffer will operate reliably while preventing a rifle length barrel and gas sytem from causing excess battering. I'm leaning with the H2 buffer at this point.
And please guys, can you just accept it that.....I'M NOT DUMPING MY BRAND NEW SOPMOD stock and tube. If I hear "Vltor" one more time...:suicide2:
Blankwaffe
03-25-11, 17:28
Iraqgunz is right,the most positive route to take is try the different buffers with the ammo you plan to use.Test the function in both clean and fouled condition.
If your going to run 5.56 NATO pressure ammo 100% of the time or heavy OTM's just run the H or H2 buffer.
Otherwise the standard CAR buffer will/should run with just about any .223 Rem or NATO spec ammo,so I'd start there and see what you have.
My builds are:
-Armalite M15A4 20" SPR barreled uppers.
-LMT M16 BCG's.
-LMT Defender 2000 SOPMOD'd lowers.
That said my next C7A2 type build will have an A5 stock assy.
Here is a couple of the posts I made on the subject last year:
"Im running two Armalite 20" M15A4 SPR uppers on LMT Defender SOPMOD'D lowers.Barrels are advertised as 1:9,but rod out closer to 1:8.
In general I have found the CAR buffer to be the most widely acceptable of varying ammo in my rifles.Particularly .223 Rem spec 50-69gr.,which I use the majority of the time.
The H and H2 run without issue with true 5.56 NATO pressure ammo(and some heavy OTM's).
Overall I'd recommend getting the CAR,H and H2 buffers,run a selection of ammo and function test with the rifle to see which buffer is the best for you.
As for gas port size on my barrels....I have no idea.I simply went through the buffers until the rifles choked with various ammo and made my notes.
For more info do a search for C7A2.Several of the SME'S and IP's have posted a ton on info on this configuration. "
"Here is one of the posts that KevinB,Nick and others discuss the buffer weight for the C7A2.
https://www.m4carbine.net/showthread....highlight=C7A2
What I gather from all the info provided in the past on the subject,the C7A2 buffer selection was based on overall performance as a do all plug and play with various barrel length uppers from 10"-20" and was tested and setup to run 5.56 NATO spec type ammo.
As always I'd appreciate correction in my assumptions.
In my experience with my weapons(sample of two non-govt standard) if lower pressure .223 Rem(particularly underpowered ammo like UMC or Wolf) is to be used the buffer selection will have to be explored as I noted above.
HTH
ETA
On the balance of the weapon configuration.My barrels are what I call between HBAR and medium contour.With the SOPMOD,standard A2 handguards,ADM with Burris FFII Tactical 3x9x40 mounted foward the balance point is at the Delta.With a loaded 30rnd mag the balance point moves slightly rearward.
YMMV "
OP: That picture on the first page is the break down of how many tungsten and steel weights are in each buffer. If you already have a CAR buffer, buy a H3 and make the different weights from the components to see which buffer shoots reliably in your rifle. Get the heaviest weight that your rifle can fire but not short stroke and lock back and then go one lighter or keep it at the heaviest. At least this way, you don't have to buy three H buffers to see which one is best, and the cost is only the one buffer.
And please guys, can you just accept it that.....I'M NOT DUMPING MY BRAND NEW SOPMOD stock and tube. If I hear "Vltor" one more time...:suicide2:
The SOPMOD would still work with the Voltor tube wouldn't it?
Yes it would.
I have a LMT receiver extension and I'm not a big fan of the dry lube coating they put on it. As of right now it's on the short list of things I need to sell.
I also think just slapping the heaviest buffer possible is a bad choice. You're trying to balance buffer/spring with the gas system. Everytime you add weight to the reciprocating mass you are changing a few things. You may reduce the felt recoil on the rearward stroke, but now you have a lot of mass going forward, which is also a componet of the recoil you feel. I've tested it with the A5, and I plan on running a few different carbine buffers and see how it all comes out.
With how soft my 16" intermediate shoots, I'm actually thinking of trying an AR15 bolt carrier, as opposed to the FA M16 one in there now.
I would suggest buying more than one buffer and trying them out in your rifle, to see how it actually feels, and not depend on Internet advice w/o ever having felt the effects for yourself.
G&R tactical has CMT buffers for very good prices. They are stamped correctly, unlike the RRA I came across at a local gun store. It was an H2, but didn't have any markings on the face.
I hate to break this to you, but you are going to have to try it out and see. Unless you can contact RRA and find out what gas size their ports are.
My guess is that it is overgassed like many others.
What's the proper gas port diameter for a 20" barrel?
Perhaps, I didn't provide enough info?... I already have the complete LMT SOPMOD collapsible stock
If you already have the complete stock, go install it and see how you like shooting it the way it came. The complete assembly should have come with everything you need, so ignore the internet and get to shooting. If at some point you don't like the way it shoots, look at a heavier buffer then.
I have a 20" Colt upper and an running a H2 in a UBR. No issues with Wolf,Brown Bear and Nato 193/885.
Yes it would.
I have a LMT receiver extension and I'm not a big fan of the dry lube coating they put on it. As of right now it's on the short list of things I need to sell.
I also think just slapping the heaviest buffer possible is a bad choice. You're trying to balance buffer/spring with the gas system. Everytime you add weight to the reciprocating mass you are changing a few things. You may reduce the felt recoil on the rearward stroke, but now you have a lot of mass going forward, which is also a componet of the recoil you feel. I've tested it with the A5, and I plan on running a few different carbine buffers and see how it all comes out.
With how soft my 16" intermediate shoots, I'm actually thinking of trying an AR15 bolt carrier, as opposed to the FA M16 one in there now.
I would suggest buying more than one buffer and trying them out in your rifle, to see how it actually feels, and not depend on Internet advice w/o ever having felt the effects for yourself.
G&R tactical has CMT buffers for very good prices. They are stamped correctly, unlike the RRA I came across at a local gun store. It was an H2, but didn't have any markings on the face.
you have an intermediate 16" gun? or is it a midlength? if you truly have an intermediate 16er, then it should be no surprise that it's soft shooting... but either way, why would you ever have a problem with a soft-shooting rifle, so long as it functions? and if your weapon shoots that soft, changing carriers isn't going to offer a perceptible difference.
I put a RRA collapsible stock on my Colt 6601 and it runs fine with the standard carbine buffer.
you have an intermediate 16" gun? or is it a midlength? if you truly have an intermediate 16er, then it should be no surprise that it's soft shooting... but either way, why would you ever have a problem with a soft-shooting rifle, so long as it functions? and if your weapon shoots that soft, changing carriers isn't going to offer a perceptible difference.
Yes, it's a 11.5" intermediate gas system on a 16". It's a custom MSTN/Noveske barrel. It's new enough, that I'm not aware of anyone else that has one. Wes Grant had a post on TOS about it under the new products section. I don't know what is ideal with the system until I try it out.
There is this new trend whereas people want to make things as heavy as possible when it comes to carriers and buffers. I'm not convinced this is at all necessary. There is more than one phase to recoil, and making things heavy addresses only one of them.
Going to a lighter carrier is something that is popular in competition circles. JP makes ultra light carriers that are designed to be used as such. I don't have an intrest in them, just the idea behind it.
When I had a extra power carbine spring, the carrier slammed forward with much greater force. The rear movement was light, but the carrier going forward was more noticeable.
Excellent question. Unfortunately my brain cannot retain all that info. However, I believe that I have seen it posted before and it should be around .090.
Don't quote me.
What's the proper gas port diameter for a 20" barrel?
Excellent question. Unfortunately my brain cannot retain all that info. However, I believe that I have seen it posted before and it should be around .090.
Don't quote me.
.089-.096
I like to think that the Canadians may have put millions of rounds downrange in the last twenty years, in temperature extremes that people here may not have shot in. I like to think that along the way they learned a lot about what buffer they need.
But hey, couple of guys threw a car buffer in and so far it's working.
I like to think that the Canadians may have put millions of rounds downrange in the last twenty years, in temperature extremes that people here may not have shot in. I like to think that along the way they learned a lot about what buffer they need.
But hey, couple of guys threw a car buffer in and so far it's working.
my guess would be that the canadian military is no different than any other military, and that they use whats handed to them, and if it works most of the time, any problems they have get blamed on user error, bad luck, improper maintenance, etc.
i agree to a degree- if thought was put into it, which it obviously was, then they left the weapon over-gassed, like most military weapons. over-gassed is better than undergassed, when we're talking about limiting common problems.. but that doesn't mean that a different weight won't work better for an individual.
like markm noted about the above photograph, homeboy canuck's brass is heading out to about 2 o'clock... put an H3 in there, and it'll probably pop out at 3:00-3:30.
I understand that the OP made some kind of comment about us pulling the H buffer and spring out of an LMT SOPMOD kit he purchased from us nearly two years ago.
I just wanted to take a moment and set the record straight. Per LMT, they did NOT start to include the H buffer and carbine spring till 2011!
Here is the e-mail from them:
Grant
We made the change for 2011
Ryan Johnson
Sales Representative
Lewis Machine & Tool Co.
1305 West 11th Street
Milan, IL 61264
Phone: 309.732.9527
Fax: 309.787.2636
Email: johnsonr@lmtdefense.com
C4
Hmmmm......just when I was settling on an H2, you've got me wondering. You seem know something more then folks like this other one-track minded guy who goes to sleep with a Vltor butt at night.
Ok....if the Canadian C7A2 operates fine on the lighter stuff.....I wonder now if I should use an H3 for the steady diet of 77 grain loads. It makes makes sense ....... assuming that you're correct that the C7A2 does use the H3 buffer. Just curious; how do you know this about a Canadian AR15 variant?
The issue now is just trying to make the right choice from the start and avoid tossing about $50 bucks on the wrong buffer and the shipping charges.
dude, can that sarcasm shit right now and stop acting like my 15 yr old when told something he doesn't want to hear. if people are telling you an A5 conversion is the best choice, it's because it is.
there's nothing wrong with wanting to keep your LMT RE but you asked for help and folks are giving you their best advice. sarcasm and whining is not conducive to folks wanting to give help in the future.
now, if you're in love with the LMT RE, your best choice is to start with either the H3 or H2 buffer as has been suggested.
however, if you want the BEST solution, swap out the RE with an A5 kit which includes the RE, spring, and buffer - it was designed to do exactly what you want to do. and it WILL accept your SOPMOD stock if that's what you're in love with, but when fully collapsed will leave a small space between the stock and lock-nut. the VLTOR EMOD will collapse fully on the A5 RE because it is longer but is not necessary.
good luck...
Dude, seriously? Don't use logic in this thread. That would be too easy.
dude, can that sarcasm shit right now and stop acting like my 15 yr old when told something he doesn't want to hear. if people are telling you an A5 conversion is the best choice, it's because it is.
there's nothing wrong with wanting to keep your LMT RE but you asked for help and folks are giving you their best advice. sarcasm and whining is not conducive to folks wanting to give help in the future.
now, if you're in love with the LMT RE, your best choice is to start with either the H3 or H2 buffer as has been suggested.
however, if you want the BEST solution, swap out the RE with an A5 kit which includes the RE, spring, and buffer - it was designed to do exactly what you want to do. and it WILL accept your SOPMOD stock if that's what you're in love with, but when fully collapsed will leave a small space between the stock and lock-nut. the VLTOR EMOD will collapse fully on the A5 RE because it is longer but is not necessary.
good luck...
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