School Me- Why Light Weight bolt/carrier & buffer for AR15

[dumbhunter]

Hey y'all-
So everything I see says heavier is better in an AR15's bolt/carrier group and buffer, but I was looking around and JP Rifles makes a light weight drivetrain... So that got me thinking- why would JP be putting out a light weight system when everyone else seems to be going heavy weight? Does a light weight system have any advantages over the standard or heavy systems?

thanks

 

[Z-Michigan]

Light weight systems are intended for 3-gun competition guns made to shoot with as little recoil and muzzle rise as possible. They generally require some tuning and may not be reliable when dirty or using anything but the one load they are tuned for.

The heavier carrier/buffer setups you typically see in service type carbines are intended mostly for reliability.

The really confusing part is that many people feel that their carbines have less felt recoil with heavier buffers, while the competition crowd favors lighter setups for less felt recoil and muzzle rise. I can't really square the two, except that people going heavier are typically running full power 5.56 NATO ammo, while the 3-gun crowd are often (but not always) running less powerful ammo.

 

[Kurt_D]

More or less +1 to the above poster.

Light weight for 3 gun and comp = faster cycling = faster shooting. Yes, some real good shooters can pull the trigger faster than a "stock" AR can cycle. The brakes and shear weight of the rifle usually handle the recoil while the BCG and buffer gets the cyclic rate up.

Heavy weight for reliablity = slower moving = less felt recoil (BCG bottoming out). The whole purpose of the H1, 2, etc. carbine buffers is to slow down the cyclic rate caused by the higher port pressure of the carbine gas system. That equals less FTFeed, less wear and tear on extractors, etc. and a lessened felt recoil pulse. You'll notice rifle lenght gas sytems use pretty much the same buffer from M16/SP1 to M16A4/current ARs. Many will commit on how "soft/smooth" the recoil feels on a rifle, even if it's a KISS SP1 (lite weight) vs a M4gery w/ rails, grip, and optic. That's due to the lower port pressure and the rifle buffer being longer and heavier even compared to a carbine 9mm buffer.

 

[Bartholomew Roberts]

It is a subjective thing. With the lighter weight, the time over which recoil is felt seems less and there is less reciprocating weight. With a heavier system, the recoil is spread out over a tiny bit longer time period, giving it more of a push then a punch; but more reciprocating weight.

 

[Zak Smith]

I've used lightweight bolt carriers and/or buffers since 2004. I generally shoot either commercial match ammo up to full-power mil-spec ammo, e.g. M193.

The lightest of the systems, such as the original aluminum JP bolt carrier and lightweight buffer, can be very finicky for reliability. But it does have very little felt recoil and almost no sight picture movement. I prefer to use a regular carbine buffer and a lightened steel carrier such as the one from Young Mfg. This combination is as reliable as a regular setup but is faster shooting. No tuning. I always run full gas.

Compared to the masses and spring rates specced stock, a slower system will mask magazine-related feed problems, which are the primary source of malfunctions.

 

[madcratebuilder]

Light weight systems are intended for 3-gun competition guns made to shoot with as little recoil and muzzle rise as possible. They generally require some tuning and may not be reliable when dirty or using anything but the one load they are tuned for.

The heavier carrier/buffer setups you typically see in service type carbines are intended mostly for reliability.

The really confusing part is that many people feel that their carbines have less felt recoil with heavier buffers, while the competition crowd favors lighter setups for less felt recoil and muzzle rise. I can't really square the two, except that people going heavier are typically running full power 5.56 NATO ammo, while the 3-gun crowd are often (but not always) running less powerful ammo.

+1

The light weight rifles generally run .223 and can be problematic with 5.56 nato. The heavy carrier/buffer rifles can choke on the low power .223 and some steel case ammo.

 

[wanderinwalker]

Wouldn't these lightweight parts also reduce the jarring of the rifle as the buffer drives the carrier back into battery? I notice with my Highpower AR-15 that sending the bolt home to chamber a round wants to pull the rifle forward. Not necessarily a huge, insurmountable force, but noticeable. It would be logical to assume lighter parts would reduce this effect.

As a note, I've never had a chance to try a .308-class AR, but a couple of people I shoot with described the "forward recoil" sensation as being strange at first.

 

[Tirod]

Try the forward recoil of the HK91. Massive bolt carrier.

The point of the optional parts is exactly that, to tune the guns recoil response and reduce muzzle movenment. So, even tho the gas port may not be modified, it is nonetheless "tuning" the action to change it's original response.

Another factor is higher bolt speeds, which reduces the time to lock and cuts the delay for a second shot. Three gun is a timed competition, unlike combat, where reliability is considered much more important. Paper targets might be unforgiving, time marches on, neither shoot back to eliminate you from competition. On a range, the tradeoff is acceptable, in a duty gun, not. Getting hit raises the risk your teammates will be.

That's why range race gun parts should stay on the range, and are questionable in other uses. Even now, the standard is only specially trained and experienced shooters use modified guns on a two way range. They're the only ones who can take advantage of the incremental difference anyway.

 

[Zak Smith]

Less reciprocating mass will reduce two of the recoil related impulses: when it bottom out and when it slams home.

Actually, when time marches on and your gun is down in a 3-Gun match, it will effectively eliminate you from competition. If you're shooting at a high level of competition, even having one rifle malfunction can knock you from contention on a rifle stage. Reliability is one of the optimized parameters in 3-Gun because you can't win if your rifle malfunctions.

As for "light weight rifles can choke on 5.56 nato" -- not my experience at all. Using the lightest of the systems ever available and full-power gas, a clean JP CTR-02 rifle (their match AR) would run great with XM193. Rifles built wrong will commonly choke with different ammo. When you look at rifles that are built right, they will operate with a variety of ammo from commercial .223 up to full power M193, and changing a buffer or a bolt carrier to adjust the weight a little bit won't make a difference. The only "good" rifle I've seen that had a legitimate problem with different ammo power was a 7" full-auto.