School me on buffer weights

[Spdu4ia]

I’m trying to find the ideal weight buffer for a new build with a 18” barrel, rifle length gas, suppressed, no adjustable gas block running a full mass BCG. That search has lead me to many different options on buffer weight. I don’t understand the effects that a heavy or light buffer has on the system.

Maybe someone can explain it in a way I can understand ?

[TFOGGER]

As I understand it, the heavier the buffer, the slower the bolt rearward velocity, the heavier the spring, the less travel for a given gas volume

[Wolfshoon]

Fogger pretty much has it covered for theory. You are trying to get the lightest/smoothest recoil impulse that will reliably cycle the weapon with a wide variety of low to high powered ammo. Your barrel port location and opening size play a big part in this as a lot of mfgrs tend to put too big of a port hole in the barrel so it will run with crappy blaster ammo. You all ready have the best barrel length as an 18" is the shortest barrel that works with a rifle port location.

Something else that plays heavily is what type of receiver extension are you using? Rifle or carbine? Rifle buffer systems are the smoothest, testing usually needs to be done with carbine length receivers to find the best combo. There are 4 weight types for the carbine system: carbine, H(sometimes called H1), H2 and H3 with H3 being the heaviest. I use the heaviest buffer I can run with the lightest powered ammo and still lock the bolt back on last round fired. Most of my carbines are a H1 or H2 but my suppressed rig runs a H3. A suppressor will typically act like a longer barrel with a little more gas coming back to operate the system.

If you are going to use a carbine receiver extension, there is also a hybrid system called the vltor or A5 system that is basically a rifle length system compressed into a carbine extension with different H values available, but it is pricy and it's parts are proprietary.

[20X11]

The heavier the buffer, the more "delay" you get in Bolt unlock time, allowing the case to cool slightly more for easier extraction. The problem with a heavier buffer in an 18" rifle gas barrel is that you have a shorter gas pulse (the time/distance from when the projectile passes the gas port to when it exits the barrel) and you may not have enough of a gas pulse to allow for a longer unlock delay and fully cycle the BCG.
Hope this helps.

[Spdu4ia]

So is it a safe assumption that running an 18" barrel with a suppressor on a rifle length gas tube and a rifle length extension with an H3 buffer would be the most effective and smoothest option? If I understand that correctly

[20X11]

The suppressor will increase the gas pulse, but whether that will run for sure with an H3 buffer or not in your particular setup is a matter of experimentation.

[KS63]

Get an adjustable gas block with a standard carbine recoil spring and a H2/3 buffer. Adjust the GB until the bolt locks back on empty and cycles reliably with the ammo you’re using.

[Tim K]

It can be affected pretty dramatically by ammo. I had a gun that ran like a champ for years with varget. I changed powder to TAC, and it's unlocking too soon and popping primers. Fiddling with the adjustable gas block didn't help. In my case, I'm going to go to a full mass carrier as I'd been running a light one. Take your best guess and try it with your preferred ammo. Further tuning may be required.

[Great-Kazoo]

Here's 2 reads regarding buffers. weight, which one etc. JP is or was the standard for other than stock AR types. There's a company that's offering a silent capture style, without the ability to adjust weight also. Then there's the taccom3g one which, based on other then arfcom sites seems to be a very good choice. I run a Taccom3g BCG in one of my 9mm AR's and very happy with it and other 3g products i have.



http://www.rifleshootermag.com/gunsm...ight-on-ar15s/

https://www.strongsidetactical.com/buffers-and-springs/

[MarkCO]

JP Flatwire spring helps a little bit. At some point, especially with overgassed ARs, you get so much mass that the muzzle dips at closing.

The whole operating system is based on gas volume (from ammo), gas port size (and restriction which determines the gas volume that goes into the BCG), dwell time (bullet velocity in barrel and length past the gas port), BCG mass, buffer mass and spring system (rates, etc.). There are 4 recoil impulses in a gas gun and there is a balance to get them as close together as possible (softer, faster on target) while also not trying to extract the case while the pressure is still elevated (hard extraction, cam path wear, hard on brass, can even gas cut chamber).

Why many folks suggest an adjustable gas block. It basically allows a serviceable tune with all the other parts you have. It is not optimum, but it will get you pretty darn close without the need to swap hard parts out hunting for a tune, so effectively, it is less costly.

And please, don't fall for some of the gimmicky stuff. Some is okay for gun racing, but some are unreliable and result in greatly increased wear.

Significantly overgassed guns are not as accurate, wear the bolt parts out faster and can lead to case separations and blow-outs of primers and or brass.

Manufacturers have been pushed towards more overgassed guns (with good ammo) due to steel cased ammo with dirty inefficient powders in the cheap ammo lines.