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Thread: H2 or H3 buffer?

  1. #111
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    If everyone is able to run these heavier weight buffers doesn't that indicate that all these carbines are way over gassed?

    I have not shot a rifle with a mid length system on it but the general consensus is that it shoots smoother than a carbine length system. What is the difference? Lower gas pressure. If you lowered the gas pressure on the carbine system to match the mid length wouldn't they shoot the same?

  2. #112
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    Quote Originally Posted by EzGoingKev View Post
    If everyone is able to run these heavier weight buffers doesn't that indicate that all these carbines are way over gassed?

    I have not shot a rifle with a mid length system on it but the general consensus is that it shoots smoother than a carbine length system. What is the difference? Lower gas pressure. If you lowered the gas pressure on the carbine system to match the mid length wouldn't they shoot the same?
    Kev,

    Negative. The people who are running these super-heavy buffers are using bolt carriers that have ultra-low friction coatings on them. The uppers have gas ports that are of the proper size for normal phosphated bolt carriers.

    Also, the gas pressure curve is different between the two lengths. Gas pressure on a carbine is higher, and is implemented over a longer period of time due to the extra dwell time (dwell time is determined by the length/percentage of the barrel found between the gas port and the muzzle. It is the duration that the entire system is under pressure).

    Locating the gas port further away from the chamber decreases peak gas pressure by 30-40% by most SME's calculations. The lower (yet still adequate) gas pressure, coupled with a shorter dwell time, means that the BCG moves rearward with much less excess energy. This is easier on the bolt/extractor and generally extends parts life. It has not yet been determined HOW MUCH the reduced stress adds to the life of these parts...but less stress always equals longer parts life if everything remains equal (and in this case it does).

    There have been many posts on gas system length (midlength and carbine length)....a search would be good to you, my friend.

  3. #113
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    I have read a bunch of the posts, that is how I came to posting what I did.

    People are swapping out their buffers whether their bolt carrier is coated or not. I really do not think the coating has all that much of an effect on things anyways.

    If company A delivers their rifle with a gas port size of .075" and an H buffer and then you put in an H3 with a higher rate spring in it and it still functions 100% then common sense would say that .075" did not have to be that big in the first place.

    No matter what gas system the rifle has it is going to take X amount of gas pressure to drive the bolt to the rear. The factors that determine X would be:
    1) Bolt carrier group weight
    2) Buffer weight
    3) Action spring rate
    4) Bolt carrier design
    5) Lube

    If all of these (5) things are equal and a mid length system will cycle the bolt with 30-40% less gas pressure than a carbine length system then you should be able to reduce the gas pressure on the carbine length system 30-40% with a smaller gas port and it should still cycle the bolt.
    Last edited by EzGoingKev; 02-13-11 at 00:45.

  4. #114
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    Quote Originally Posted by Neo Mara View Post
    I saw the pictures on the site but your post led me to think you had had a custom buffer made unlike the ones listed on his site.
    I did have a custom buffer made, in a sense. I had Clint use an XH buffer body and drill it out to accept three internal reciprocating weights as opposed to the two (tungsten) weights that normally are found inside the XH body. This reduced the buffer body weight (which is directly coupled with, and added to, the weight of the BCG) in favor of an increased proportion of reciprocating weight (the stuff that quells bolt bounce).

    I'm sorry for the confusion.

  5. #115
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    Quote Originally Posted by EzGoingKev View Post
    I have read a bunch of the posts, that is how I came to posting what I did.

    People are swapping out their buffers whether their bolt carrier is coated or not. I really do not think the coating has all that much of an effect on things anyways.

    If company A delivers their rifle with a gas port size of .075" and an H buffer and then you put in an H3 with a higher rate spring in it and it still functions 100% then common sense would say that .075" did not have to be that big in the first place.

    No matter what gas system the rifle has it is going to take X amount of gas pressure to drive the bolt to the rear. The factors that determine X would be:
    1) Bolt carrier group weight
    2) Buffer weight
    3) Action spring rate
    4) Bolt carrier design
    5) Lube

    If all of these (5) things are equal and a mid length system will cycle the bolt with 30-40% less gas pressure than a carbine length system then you should be able to reduce the gas pressure on the carbine length system 30-40% with a smaller gas port and it should still cycle the bolt.
    Yes, people have been swapping buffers with std BCGs with varying degrees of success. The only way I know to go heavier than an H3 (using a std BCG) without sacrificing reliability is to use Vltor's excellent A5 RE and buffer w/ a rifle spring.

    In my limited experience, you are incorrect about the coating; it has LOT to do with the way the BCG behaves inside of the upper. How else could I run an 8oz buffer with a up-rated action spring on an upper that IG and Markm have seen start to malf due to excessive buffer weight while using a 5.4oz H3 buffer and a std BCM action spring, being tested with the same ammo?

    They have a LOT more experience than I do, and clearly they encountered a design limitation using a std phosphated BCG and an H3 buffer. I'm adding ~3oz on top of that AND using a heavier spring. That is simply not possible using a phosphated BCG. I tried it w/ my CMT. FTR, using my CMT BCG, I too found that an H3 would cycle too slowly using some types of weak 223 in my BCM 14.5" middy.

    I agree with your list except for #5. Lube addresses friction and that is what belongs in its place. Friction does play a major part in function.

    As far as pressure curves and gas system lengths, people much smarter than I have shown the midlength to be more forgiving as to ammo type and ammo pressure. There are some LMT carbines out there that have rather small gas ports...they shoot NATO pressure stuff REALLY softly (and with great reliability), but they won't even cycle using Wolf or Tula or some American Eagle or PMC SAAMI pressure ammo. The BCM/DD/Centurion/Noveske/KAC midlengths have been shown to cycle NATO pressure ammo as softly as a barely-there gas ported LMT, and still run the weaker ammo types without issue.

    That's the extent of my knowledge on the topic. For more you'll need an SME to chime in.

  6. #116
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    Okay so the OP wants to switch to a new buffer. Has anyone asked the OP why? Is there a problem with he is trying to fix or is he trying to fix a problem that is not there and just trying to "upgrade." Is he running suppressed? The buffer and spring are there to counter the rearward movement of the BCG. There are a lot of factors that contribute to what weight buffer you should use. Gas port size, carrier, ammo, suppressor, buffer spring strength, etc. The biggest concern is the gas. Is the rifle overgassed (i.e. gas port too big)? If NOT, then putting an H3 or even an H2 could cause short stroking, and you just wasted you money. If it is overgassed, then try out a new buffer. But if you want the softest recoil possible with your rifle yet the same reliability you have now or better, go with a VLTOR A5 system. It will give you great recoil management and great reliability.

    But if you juts want to upgrade your buffer for the sake of upgrading your buffer, then go for it, it's your rifle and your money.

  7. #117
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    Quote Originally Posted by BufordTJustice View Post
    In my limited experience, you are incorrect about the coating; it has LOT to do with the way the BCG behaves inside of the upper.
    If you have two rifles configured with the same specs/parts but have one use a TiN/DLC/EXO/Chrome/Whatever coating while the other one is standard.

    Shoot them dry and you could see a discernible difference but shoot them good and wet and the difference is not going to be all that much.

    Quote Originally Posted by BufordTJustice View Post
    I agree with your list except for #5. Lube addresses friction and that is what belongs in its place. Friction does play a major part in function.
    Lube is there because it belongs there. It is much easier to quantify.

    You can go out and shoot your rifle with CLP and then clean it all off and use wheel bearing grease on it and record your findings.

    You cannot go out and set the friction to a factor of 10 and then dial it up to 20 and compare.

    I see people throwing all these parts at their rifles to improve things and have to wonder if they are looking at the wrong end.
    Last edited by EzGoingKev; 02-13-11 at 11:52.

  8. #118
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    Quote Originally Posted by BufordTJustice View Post
    I did have a custom buffer made, in a sense. I had Clint use an XH buffer body and drill it out to accept three internal reciprocating weights as opposed to the two (tungsten) weights that normally are found inside the XH body. This reduced the buffer body weight (which is directly coupled with, and added to, the weight of the BCG) in favor of an increased proportion of reciprocating weight (the stuff that quells bolt bounce).

    I'm sorry for the confusion.
    I get it now, makes a lot of sense to try it that way. If you are still getting bolt lock back on the SS body with 3 tunsten weights you could also try having him hollow out a 9mm tungsten buffer and putting tungsten weights inside. Sould allow for the heaviest carbine size buffer possible while still having free flaoting weights inside.

  9. #119
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    Quote Originally Posted by Evil Bert View Post
    Okay so the OP wants to switch to a new buffer. Has anyone asked the OP why? Is there a problem with he is trying to fix or is he trying to fix a problem that is not there and just trying to "upgrade." Is he running suppressed? The buffer and spring are there to counter the rearward movement of the BCG. There are a lot of factors that contribute to what weight buffer you should use. Gas port size, carrier, ammo, suppressor, buffer spring strength, etc. The biggest concern is the gas. Is the rifle overgassed (i.e. gas port too big)? If NOT, then putting an H3 or even an H2 could cause short stroking, and you just wasted you money. If it is overgassed, then try out a new buffer. But if you want the softest recoil possible with your rifle yet the same reliability you have now or better, go with a VLTOR A5 system. It will give you great recoil management and great reliability.

    But if you juts want to upgrade your buffer for the sake of upgrading your buffer, then go for it, it's your rifle and your money.
    Bert, you ARE aware that new Colt carbines going to the military are shipping with H2 buffers, right? They are.

    Heavier buffers ease extraction, allow the case obturation to finish, and also serve to smooth the recoil stroke.

    Any mod that sacrifices reliability is one that's only for fools. However, I am up to about 1100 rounds on my 7.3oz buffer...shooting mostly nasty Tula, with 100% reliability.

    There is nothing special about he Vltor A5 that allows it to use a heavier buffer than a normal carbine RE except that it allows for the use of the softer (but with more even pressure through its stroke) rifle spring.

    I'm not sure what you're getting at by sh*tting all over some good and honest experimentation that I and others have conducted.

    I have experienced no adverse effects on reliability and a greatly smoothed recoil stroke: you show me the downside.

  10. #120
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    Quote Originally Posted by EzGoingKev View Post
    If you have two rifles configured with the same specs/parts but have one use a TiN/DLC/EXO/Chrome/Whatever coating while the other one is standard.

    Shoot them dry and you could see a discernible difference but shoot them good and wet and the difference is not going to be all that much.
    In my experience you are wrong, sir. I A/B'd the NiB BCG w/ my CMT FA group using Slip 2000 EWL AND Slip 2000 EWG (grease) and the difference was notable between the two. I still could not run the super heavy buffers using the CMT group, but could with the NiB. Same ammo. Same Upper. Same range day.

    Quote Originally Posted by EzGoingKev View Post
    Lube is there because it belongs there. It is much easier to quantify.

    You can go out and shoot your rifle with CLP and then clean it all off and use wheel bearing grease on it and record your findings.

    You cannot go out and set the friction to a factor of 10 and then dial it up to 20 and compare.
    I'm not trackin' on your point. Friction is an ever-present evil in engineering, and reducing it is still a good thing last time I checked.

    I was already running my CT carrier as sopping-wet as I could...no more lube could be added. So, tell me how using a coating that was developed to reduce friction is a bad thing.

    Quote Originally Posted by EzGoingKev View Post
    I see people throwing all these parts at their rifles to improve things and have to wonder if they are looking at the wrong end.
    Brother, I heard the same bullshit when red dots came out, when midlength gas systems were developed, when the battlecomp was invented, when the PMAG came out, etc. Your back-handed comment about pushing what the platform is capable of is what stifles innovation. If you don't like it, then don't do it. This was actually thread-drift from the start, as my direction to the OP echoed IG; use an H2 buffer and be done with it.

    Since you know so much about me and my inadequacies at using said carbine, how about you tell me some more about myself.....really, I'd like to hear it. Save your condescending bullsh*t for TOS.

    Addressing an engineering/design issue in this Technical forum should NEVER be a faux paux or be subject to brow beating.
    Last edited by BufordTJustice; 02-13-11 at 16:28.

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