View Full Version : Buffer weight and perceived recoil
What is the relationship between buffer weight and perceived recoil. I see in a chart there are more than half a dozen different weights. Would changing the weight reduce perceived recoil without reducing reliable operations any? If so, do you go with a higher or lower buffer weight than standard?
It's entirely unique to your barrel, gas system, and port size.
A correctly gassed AR should run optimally on an H2 carbine or A5 buffer OR a rifle buffer system. A mildly overgassed AR will often recoil less with a heavier buffer.
For recoil characteristics, in general, heavier buffer results in a longer "push" while a lighter buffer results in more "punch"
With a properly gassed barrel, a lighter buffer shoots smoother to me.
A real heavy buffer seems to make my dot dance a lot worse than a lighter one.
Recoil is the same no matter what. Less reciprocating mass usually makes for less perceived recoil.
Gamers actually reduce felt recoil by running buffers as light as 1 oz. in conjunction with adjustable gas blocks and reduced mass BCGs. I have a 1.1 ounce buffer in an ultra lightweight I built. It runs fine with the lighter parts but I consider it a fun gun, not for serious use.
If the gun needs to be as reliable as possible, I believe you use the heaviest buffer that functions properly in conjunction with a top tier mil BCG and you let "felt recoil" fall where it may. If you want to actually dial the recoil down, you can, but you shouldn't need to depend on that dialed down gun.
I really like the softer recoil pads... I know that the AR doesn't recoil hard ... but what the heck, its my money.
^^^^ That.
When tuning recoil, one must take into account reciprocating mass & velocity, spring rate, gas pressure and margin of reliability. Not just buffer weight
thopkins22
10-03-14, 01:07
It's physics right? There are three separate things that we perceive as recoil. The immediate opposite reaction of hot gas and a bullet pushing back at you as they leave the front of the rifle, the BCG and buffer on their way backwards against the spring and spiking that force at the end of their travel, and that of them slamming forward into battery.
All else being equal and disregarding reliability concerns, heavier carriers/buffers can reduce the initial impulse for no other reason than they add weight to the rifle. The second impulse can be lengthened or "smoothened" by them because they move slower. The third impulse will always be higher with a heavier carrier and buffer.
All else being equal and disregarding reliability concerns, a lighter carrier and buffer will do less for the initial impulse(all else being equal,) but will speed up and have a lighter second impulse(though not everyone likes this happening faster, the best shooters in the world tend to.) And they will have a much lighter third impulse.
But there's a huge individual component. I strongly prefer 147gr. 9mm loads for competition...it all depends on what exactly you're trying to accomplish.
Want to fight with it? Nobody ever went wrong with a M16 carrier and an H buffer. Want to shoot the lights out at a 3-gun match? I'd say shoot it that way anyway with a good muzzle brake. Routinely placing in the top 5 or 10 of a 50 person match? Time to decide if you want to go through the rigamarole of tuning a gas block to a load and a light carrier/buffer/new springs/pixie dust.
I don't know why heavy as possible is considered more reliable. Stock Colts run fine on H buffers on any ammo.
If you've never shot a tuned race rifle with big brake and low mass reciprocating parts, you've never felt soft and smooth.
They're not hard to make reliable with full powered ammo at all. Pretty much drop on al the JP stuff and go play.
It's like the heavy recoil spring crowd with pistols. People think it helps, but all it really does is kill the way the pistol shoots.
I don't know why heavy as possible is considered more reliable. Stock Colts run fine on H buffers on any ammo.
They should be running H2s. Colt is slightly behind the times... The H2 most closely matches the physics of the Rifle buffer system. Colt errs on the side of reliability with a slightly light buffer.... whereas bottom feeders just put a huge port in the barrel.
The reason the heavier buffer increases reliability is that is slow and smooths out the cycle. Thus giving the mag follower more time to push a round up into feed position. And the increased forward moving mass pushes the next round into the chamber with a little more force.
Adding mass works because when it comes to momentum (which is mass & speed) speed is a variable, mass a constant. For example, if the action gets crudded up and the lube dries up, the carrier will run slower. In that case, chances are a low speed, high mass carrier will bull it's way through the muck better than a high speed, low mass carrier
Agreed... and bolt bounce, which used to be a major problem back when carbines came with carbine buffers, is greatly reduced.
I think the bolt bounce problem is related to a lack of damping rather than a lack of mass. The greater mass of the heavier buffers is in the damping material. I should have added that using too much mass has it's own set of problems. While it's pretty easy to get the rifle to run reliably or to soften it's recoil, it's a delicate balancing act to get the rifle to run reliably and soften recoil
I think the bolt bounce problem is related to a lack of damping rather than a lack of mass.
Yeah... you're probably right... with the buffer weights being so light in a plain old CAR buffer, they're probably not as effective at damping the carrier movement since the carrier far outweighs the buffer/weights.
I should have added that using too much mass has it's own set of problems.
No question about it. I've messed with both sides of the balancing. I think there's relatively forgiving middle ground where you can be +/- one buffer weight and be fine.
BufordTJustice
10-03-14, 11:42
Mist and Mark pretty much covered all the bases.
I would only expound on what Mist said about the balancing act. If you go too heavy on the reciprocating weight, you can get muzzle dip on the BCG's return-to-battery stroke.
Yep. I've seen a few guys post about experiencing muzzle dip when rapid firing.
With a semi auto carbine with a reasonably close gas port size and mostly fresh springs it almost doesn't matter. They will just about run on anything.
It takes a lot of finger banging to make a 6920 unreliable.
Colt buffers lighter to err on the side of reliabilty so you go heavier to err on the side of reliabilty. Makes perfect sense.
I have a 14.5" DD carbine gas upper that has run fine on H, H2, H6, A5-A5H3. Almost imperceptible recoil difference. I stayed with the A5 because it sounds theoretically better.
Colt buffers lighter to err on the side of reliabilty so you go heavier to err on the side of reliabilty. Makes perfect sense.
Is there ANY topic you have a half a clue on? The unbiased facts point to the H2 buffer as the optimal solution. If you're only capable of doing what Colt, who at one time put a solid polymer buffer in rifles for commercial sale, does... then so be it.
You're incapable of original thought. I get it.
Ha! Maybe I don't have a clue, but dumb luck must favor me because I've never had any real reliabilty issues that were more than a simple fix. Handgun or carbine.....
In my testing I've found an H2 to be the heaviest I can go before I start seeing muzzle dip due to reciprocating mass. And since I assume that it is desirable to have some mass to drive through less than optimal conditions, I tend to stick to the H2 if I can.
Time for a couple of dumb questions...
Does the perceived recoil change in large part because you're changing how hard the buffer impacts the back of the receiver extension?
And if so, in a so called properly functioning carbine does the buffer still impact the back of the receiver extension?
BufordTJustice
10-04-14, 09:41
In my testing I've found an H2 to be the heaviest I can go before I start seeing muzzle dip due to reciprocating mass. And since I assume that it is desirable to have some mass to drive through less than optimal conditions, I tend to stick to the H2 if I can.
Time for a couple of dumb questions...
Does the perceived recoil change in large part because you're changing how hard the buffer impacts the back of the receiver extension?
And if so, in a so called properly functioning carbine does the buffer still impact the back of the receiver extension?
Yes and yes.
I took my daniel defense 16.1 middy to the range a few weeks ago. I run it suppressed and unsuppressed. I brought m193 and pmc bronze. Fired a few hundred rounds suppressed to dirty her up and began playing with buffers and springs. I had an h, h2, colt spring and sprinco blue.
The smoothest combo and most reliable combo I found was the h buffer and blue spring. It would lock back unsuppressed held very loosely using pmc bronze (and would even run wolf 55gr military classic if I held it in a deathgrip) and ejected m193 to 4 o clock unsuppressed and around 230 to 3 suppressed. Wolf went to 4 suppressed and felt like a dream to shoot with the can. So for the with that setup, h buffer and blue sprinco did the trick.
H2 buffer with colt spring wasn't much different from h. H2 with blue sprinco was giving reliability issues unsuppressed with pmc bronze (my "lowest common denominator" ammo).
We were out shooting yesterday and Pappabear brought his 10.5 LMT. Little did I know he was running a 100% stock lower with the LMT Carbine buffer. HOLY SMOKES did that thing buck. Amazingly it still functioned great.
I moved the upper onto my H3 buffered A5 that's off of my 10.5, and it really got the recoil under control. It was really uncomfortable to shoot prone, and bucked hard when shooting rapid fire, off hand.
I put H2 buffers in all our 16" barreled carbines with carbine gas systems. They function fine with 55/62gr. 223 Rem. or 5.56 ammo. We don't shoot the cheap steel stuff. We have shot some PMC ammo without issue though.
NYH1.
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