So commencing my first 308 rifle project, but I'm not sure which way to go with a setup.
I'm thinking a 1-4x/1-6x optic, so either a 16" or 18" barrel, but those parts are a ways off due to funding.
Right now though I'm planning on just completing the lower and all of the small parts for the upper receiver.
This brings up the question rifle buffer system or carbine.

Does the rifle buffer system make a notable impact on recoil compared to the carbine one?

I would pick based on what kind of stock you want to have on the gun. Either way I would HIGHLY recommend getting an adjustable gas block. It will have a much bigger impact on recoil than the buffer.

The gas port diameter, location, gas leakage around the block and tube, type of ammo, projo weight, dwell time, BCG weight, recoil spring strength, lubrication, and buffer weight/arrangement will all contribute to the overall felt and perceived recoil on a .308 AR.

There are at least 3 different lengths of buffers you can use on an AR10 or LR-308 build:

DPMS short LR-308 carbine buffer, must go with a standard AR15 carbine-length extension tube.

AR15 carbine buffer, must be used with ArmaLite or VLTOR A5 length medium length extension tube.




ArmaLite or DPMS AR10/LR-308 rifle buffer, must be used with AR15 rifle extension tube.

AR15 rifle buffer shown on top, AR10 on bottom


When it comes to buffer weights, you are going to have to determine that once you get your barrel.  My advice is to wait, or get several of the length you want, or get additional weights to tune the system once you have it all together.

Above post has it right.

I never recommend using an AR15 tube UNLESS you're going to splurge on the JP system, or use Slash extras heavy buffer and his spring.

Id say use a rifle length gas system even on the 16" barrel. And use the Armalite or Vltor A5 tune with an Armalite spring and H3 or heavier buffer. To me, this has been a great combination and i have no plans on doing anything different. It's either Armalite rifle length system, or Armalite carbine system.

I'm buying the rifle length system of the EE just to have on hand. Will be a good bargaining tool towards to wife to justify another AR10 build.

So what sort of problems might happen from using this?

What are some good adjustable gas blocks to use to fine tune the rifle with the different buffer weights?

Lots actually. The buffer is just too light to control the pressures involved with the 308 cartridge. You need heavier weights and stiffer springs to deal with the larger amount of gasses and pressures involved with the large frame ARs.

However, if you use an adjustable gas block, this can change things. You can lighten the bcg and buffer system and cut down the gas needed to cycle the action. Another however, you'll constantly adjust the gas block if you use different factory ammo. Not all ammo is the same, even same ammo type/brand varies lot to lot. You'll adjust your block to reliably feed with ammo A, but that doesn't guarantee ammo B or C will work.

The adjustable block is best for suppressors or competition rifles. If you want utmost reliability, you go with full gas, and mitigate pressures and recoil with the buffer system. The H3 weight is really the lightest you should go.

Awesome, thanks for all of the help.
So if I were to go that route - near full gas and put recoil reduction mostly on the shoulders of the buffer system, what buffer would you recommend? JP?

I personally like the simplicity of the Armalite system. The JP works great, can tune it as well. The JP is a little better in its own way. But they're both very reliable.

I prefer Syrac.  It is available in either clamp-on or setscrews.  I like the forward facing adjuster and the positive detents on the adjuster screw.  It sure cured my .308 function problems.