So I got some high speed video of my AR and bolt bounce is not an issue. I’m running a CAR buffer and standard spring right now on a 16" middy from ST (pencil profile barrel if it matters)
It does however appear that the bolt is slamming to the rear of the extension which makes for the highest spike in recoil impulse. I was wondering if running an H buffer or a heavier buffer spring would possibly slow down the impulse. I was considering an A5 system but I am a college student and have a budget.
can anyone proffer any pro’s and con’s of one over the other? thank you.
Yes, heavier buffers will slow the velocity of the bolt carrier.
If you slow it too much, you can induce problems. Fail to lock on an empty mag being one, fail to feed etc. Some of these can also be magazine problems, so if you’re testing use the same magazines throughout any testing.
My advice would be to buy an H3 buffer, which has three tungsten weights. This is opposite a CAR buffer which has three steel weights. You can swap them around to make an H or an H2.
Ammunition will also effect this too. So test your setup with all ammunition you foresee yourself using.
The heavier you make the moving assembly, it will change not only the recoil on the rear stroke, but forward as well.
The A5 setup is a little different, as it uses a rifle spring which has a different spring rate than a carbine spring. The A5 system uses a heavier buffer than a typically found in carbine setups, 5.33oz with the stock buffer.
It depends on your criteria… but as a gamer (3-gun) I have a solution.
Adjustable gas block, JP LMOS carrier and buffer, and possibly a comp.
I have experienced perfect reliability with the JP system in my 3-gun rifles. They get run hard, and often dirty. My only malfunctions in the past 2 years have been mag related.
Lighten up the reciprocating mass, tune down your gas until your carrier isn’t bottoming out with a lot of force, and then the comp will be working for you as well. All have drawbacks. Different brands of ammo might not run your gun if you tune it way down. Personally I don’t get greedy turning it down and my rifle runs everything. Comps are loud. Some louder than others. My friends complain about my Cooley comp.
My setup is not a valid option for a duty carbine, but depending on what you are doing with your rifle, it might work for you.
Another drawback, JP parts aren’t cheap.
This rifle shoots SOFT and flat.
This one too… but a little less so because the nordic comp isn’t as effective as the JP, and the gas isn’t adjustable, and the barrel weighs less.
I recently traded my KAC SR-15 for an LMT MRP. I kept the BattleComp 2.0 from it and threw it on the MRP. Needless to say it still doesn’t feel anywhere near as soft as my KAC did. It literally felt like a .22LR.
I think the big difference comes from the “tuned” gas port. And if you’ve ever read about SR-15’s you probably know that they some times have problems with wolf. It’s because the gas port is so small.
So an adjustable gas block or some kind of restrictor is needed for the gas system. That along with a carbine buffer and the lightest carrier and you’ll feel exactly what a KAC feels like with a comp.
What’s your time on the VTAC 9-hole? What’s your score on the MEU(SOC)? The Modified Navy Qual? Defoor Proformance Carbine Tests 1-3?
At most I’d use the H-buffer and ensure that it runs with that. Even on the mid-length I think the H-buffer is the correct part. Beyond that I’d be worried about personal performance.
On my M4 builds I always run, a Auto carrier ( These are alittle heavier than the semi auto carriers), A “H” buffer, and a Bravo company extractor spring with their black bumper.
I have Comps on a few of my guns, they do work but make the gun really loud as some of the blast is coming back towards the shooter.
I mostly shoot Federal XM193 which runs fairly hot. The guns have little recoil to them, even the ones with flash hiders.
We were out of H buffers at work so I tried an ST-T2 buffer. I’m not sure if snake oil fouling was to blame but an occasional round would hang on the feed ramp. a light shake or tap an the bolt would go to battery. replaced with an H buffer, shot a match yesterday and it ran fine. was too busy shooting to notice if it was much smoother but I will be shooting a benefit match today and will have to pay more attention.
My Spikes mid length has the Spikes ST-T2 Tungsten Buffer and it’s extremely smooth compared to the carbine I had previously. It’s almost like shooting a 20 in rifle.
I am an idiot, but I think “smooth” recoil should not be in the same sentence as reliability in an AR. The stroke is too short for the variance in everything else to be both. Go with the bounce off the extension as added energy to forward stroke and call it a day.
While overgassed guns are not good, I think you’re right. “Gamer-gassed” guns can be bad too, especially when the user doesn’t consider WHY they’re making the modifications that they make. Add an obnoxious muzzle brake, a lightened hammer spring, and one of those tiny-objective variable optics that can’t resolve shit in low lighting conditions, and you’ve reduced a useful tool into a finicky toy.
It’s not that the mid-length won’t run with a heavier buffer, it just sounds like for whatever reason, your combination is more reliable with the standard carbine buffer.
If your BCG & buffer is hitting hard on compression, that’s a problem that needs to be addressed with spring rate (or the reciprocating mass needs to be lightened). Adding to the reciprocating mass with the same spring rate usually exacerbates the problem. It takes more energy to move the greater mass but it also takes more energy to stop it.
If the BCG & buffer is bottoming out too hard, try replacing the spring. Before going with a spring with a heavier than standard rate, make sure the current spring isn’t worn or too light
H2 buffer with Spinco blue spring in my 14.5" Centurion Arms middy (1,500 rounds)-- I also run this set up in my DD 16" carbine (6,600 rounds). Both function flawlessly and smoothly.
my point is that with the variation of ammo, From Tula to M855, if you have a weapon that can cycle with the low and high end, then you may feel a little more recoil which isn’t hardly much on the hot end. If you’re got a real soft shooter with hot brass, you are screwed with reliable operation on the not so hot brass. So man up and separate the variables. It’s also very hard to have a super fast car that also gets over 40 mpg. Not a perfect world, stroke is partly the culprit.
