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Posted: 8/19/2017 8:26:33 AM EST
[Last Edit: 8/19/2017 8:33:45 AM EST by swampie]
I'm building a 308 using a CBC upper. (I know, I know, but it's what I have to work with)

It has an 18" barrel and mid-length gas.

What buffer weight do you recommend using? It will not be suppressed. I was told 5-5.5oz. Does this sound right?

Does any one sell a complete stock kit/buffer tube/spring with said buffer included? I need the complete rear end.

thanks,
swampie
Link Posted: 8/19/2017 9:56:45 AM EST
The heavier the better, even if not suppressed. But yes, 5-5.5oz should be fine.

As for butt stock kits, look at Rainier Arms, Primary Arms, or some of the other vendors that list here.

I can't say enough good things about Slash's heavy buffers too.
Link Posted: 8/19/2017 10:40:06 AM EST
Definitely no expert here, but isn't the buffer choice also dependent on gas port size, BCG weight, and even ammo? Still, you gotta have someplace to start, and ARmory04's suggestion sounds as good as any to test. It may take some trial and error.
Link Posted: 8/19/2017 2:20:47 PM EST
Link Posted: 8/19/2017 3:37:55 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By bfoosh06:
If you are building a .308 / 7.62x51 AR... then you will need specific to .308 AR10 buffers , both carbine and rifle length stocks use different sized buffers then typical AR15 buffers.

Buffer springs are different as well.... and quite possibly buffer tubes.

I ended up changing my carbine .308 stock over to a rifle length... and bought a KAK HyWt 9.3 oz .308 rifle buffer.

I also changed over to a SLR adjustable gas block.... Huuuuge improvement over the "exorcist" OEM cyclic action... much tamer BCG, etc speed.
View Quote
Just to add; the 308 carbine only needs the shortened buffer to use standard AR15 length buffer tubes. The Armalite 308 and Vltor buffer tubes are slightly longer (5/8" iirc) and can use AR15 carbine buffers. The rifle buffers are 5.200" for 308 and 5.900" for 5.56.

I currently have an 8.5oz AR15 carbine length buffer on my 308, using the longer 308 carbine buffer tube.
Link Posted: 8/19/2017 3:43:26 PM EST
[Last Edit: 8/23/2017 5:25:04 PM EST by ARmory04]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By ARTNC10:
Definitely no expert here, but isn't the buffer choice also dependent on gas port size, BCG weight, and even ammo? Still, you gotta have someplace to start, and ARmory04's suggestion sounds as good as any to test. It may take some trial and error.
View Quote
I should have been more specific, my apologies. But, generally, yes you are correct. However, with 308's pumping more gas volume, higher chamber pressures, etc, I have found in my years of building and tinkering with 308 AR's, heavy is the way to go. I can honestly say I've yet to encounter a problem from a "too heavy" buffer for 308's.

I know some members here, like SLRrifleworks custom made a 10oz(?) buffer for one their personal 308's, and also recommend heavier buffers.

I will also say that in my experience, 5.56 tends to be a little more sensitive to heavy buffer weight, while the 308 not as much.
Link Posted: 8/19/2017 3:47:28 PM EST
The big guns like heavy buffers.
Link Posted: 8/19/2017 3:47:54 PM EST
Trial and error
Link Posted: 8/19/2017 5:01:33 PM EST
Pick a bullet/load combo you want to shoot.

Build the rifle around that and the conditions you'll shoot it in.

Don't expect a wide range of fuel to run your engine on.
Link Posted: 8/19/2017 5:27:55 PM EST
[Last Edit: 8/19/2017 5:30:40 PM EST by swampie]
The barrel is a 1:10 twist so heavier bullets would probably shoot better. I have a bunch of 180gr winchester SP bullets that I can use but I also have a bunch of 150gr Barnes TSX bullets that I'd rather use, but they may not be accurate enough???

BCG is standard weight for a 308 AR

This rifle will be used primarily for deer hunting with the odd chance of black bear and elk. 300 yards max.

I am not concerned with kick. I can handle a 300 mag. 308 is no problem.

Once a load is developed, this rifle wont see 50 rounds a year.

I'm already over budget on this rig so price is a concern.

I don't want or need a fancy stock. A standard A2 stock or a Magpul MOE will be fine.

Given this info, what do you recommend? Where can I buy it?
Link Posted: 8/19/2017 5:57:16 PM EST
[Last Edit: 8/19/2017 6:42:34 PM EST by swampie]
Additional info:

My lower is a Tactical Machine 80% lower. I was told it used DPMS parts.

Rainier Arms sells Armalite AR10 rifle buffers 5.4oz and springs at very reasonable prices compared to the heavybuffers parts. For my above intentions, do I really need anything "better/heavier"?

Are the AR10 and DPMS buffer tubes interchangeable?

thanks,
swampie
Link Posted: 8/19/2017 9:42:15 PM EST
How about This buffer/spring/tube

And a MOE stock?

swampie
Link Posted: 8/20/2017 7:40:07 AM EST
Link Posted: 8/20/2017 8:58:04 AM EST
PSA's reviews on that combo arn't too great. Seems they keep sending out the wrong kit. Unless I missed something, that is a standard weight rifle buffer weighing 5.4oz. The carbine kit I picked out above has a 5.6oz buffer and it's cheaper.

I DO want my rifle to last, BUT, the upper has a lifetime warranty (Assuming they stay in business for at least 35 years), CBC recommended a 5-5.5oz buffer, and it will see less than 2000 rounds in my lifetime.

So, is longevity really a concern?

swampie
Link Posted: 8/20/2017 12:20:11 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By bfoosh06:
If you are building a .308 / 7.62x51 AR... then you will need specific to .308 AR10 buffers , both carbine and rifle length stocks use different sized buffers then typical AR15 buffers.

Buffer springs are different as well.... and quite possibly buffer tubes.

I ended up changing my carbine .308 stock over to a rifle length... and bought a KAK HyWt 9.3 oz .308 rifle buffer.

I also changed over to a SLR adjustable gas block.... Huuuuge improvement over the "exorcist" OEM cyclic action... much tamer BCG, etc speed.
View Quote
I've always gone with Slash heavy buffers but I think I may give the KAK a try.
Link Posted: 8/20/2017 12:43:11 PM EST
Instead of going down the buffer weight/spring rabbit hole, I'd suggest an adjustable gas block (SLR on mine). No addition expenses with trying buffers/spring combo's that might not work. You just tune the block for whichever combo you chose. Added bonus is you don't have to swap parts for silencer or even various ammo. All the changes are there in the gas block.
Just my .02
Link Posted: 8/20/2017 9:10:17 PM EST
An SLR adjustable gas block costs $120 Plus I'd still need a buffer, spring, tube and stock. I'm trying my best to go as cheap as possible and still remain reliable.

swampie
Link Posted: 8/20/2017 11:28:10 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By swampie:
An SLR adjustable gas block costs $120 Plus I'd still need a buffer, spring, tube and stock. I'm trying my best to go as cheap as possible and still remain reliable.

swampie
View Quote
Well how much would you spend for a buffer and spring... then another, then another (etc) until you find the right "one"? Now do it all over again when you chose a different load (such as M80 is WAY less powered than commercial stuff.. and even commercial stuff is all over the map).
I guess the point I'm making is that, although the $120 seems steep, an SLR is a "one and done" solution to all of any gassing issues (without having to swap out or buy anything from that point on).
Trust me... I'm a cheap ass. But after one non adjustable gas block 308... mine wear SLR's now (and life is soooo easy because of it).
Just my .02
Link Posted: 8/21/2017 1:26:27 AM EST
I'm in the " do it right the 1st time" crowd. Adjustable gas block makes it real easy. I used superlative arms($95). I also used the PSA PA10 tube which uses standard length AR15 buffers and their spring plus colt h3. Smooth shooter, doesn't beat the gun up and will run supressed and unsupressed without changing stuff around.
Link Posted: 8/21/2017 1:05:41 PM EST
I own two Armalite AR-10's, a 16" mid-gas and 21" rifle-gassed. Both barrels are Noveske's. I went with Slash's heaviest buffer right out-of-the-gate. They have been excellent rifles, very smooth, reliable and accurate.

I'm running the B model that used the old school metal magazines. Not the newer A model that uses the DPMS pattern mags.

1/10 will shoot all bullets well. The heaviest I use are 175 grain SMK's. My standard load is 40.7 grains of IMR-4064 or 41.5 grains of VihtaVuori N150 in Lake City or IMI brass and 168 grain SMK's.

I have Vltor standard SS gas blocks that John pinned in place. You don't need an adjustable GB if you aren't going to wander to for from my ammo choice. Trying powders or bullets on the edges of normal (lighter than 150 heavier than 175) may put you in no-man's-land.

My first pick for one powder if I could only choose one, would be IMR-4895.
Link Posted: 8/21/2017 3:54:17 PM EST
[Last Edit: 8/21/2017 3:55:42 PM EST by heavymetal762]
I've got a CTS Aktiv buffer in both of my 308 guns and most of my 5.56 guns. They work, and make the action feel like it's on roller bearings. They are a no-shit-it-works upgrade.

ETA: my 308 guns are an 18" middy and a 16" middy. Both run noticeably better with the Aktiv.
Link Posted: 8/21/2017 6:50:48 PM EST
[Last Edit: 8/21/2017 6:58:47 PM EST by Ghostface]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By LRRPF52:
Pick a bullet/load combo you want to shoot.

Build the rifle around that and the conditions you'll shoot it in.

Don't expect a wide range of fuel to run your engine on.
View Quote
I tend to agree with most everything that you post but I have to disagree with this one. All of my Armalites have either a PRI fully adjustable gas block or a copy of it and a Tubbs flat wire spring along with the Armalite H3 buffer. I'll admit the Tubbs wasnt needed but it did smooth things out.I have shot everything from weird power curved ZQI which at first would not function but I finally figured out I had to damn near shut the gas off to get it to run, to a wide variety of different weight match bullets from 110-190 grains. In my experience it is best to use an adjustable gas block over a heavy buffer alone simply because of you can tune the gas to the load that you are shooting. You cant really do that with just a heavy buffer. Why limit yourself?

ETA OP you can get adjustable gas blocks pretty cheap, Anderson Arms has one for around $50 if your barrel is .750....
Link Posted: 8/21/2017 7:23:12 PM EST
Link Posted: 8/22/2017 3:55:42 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By heavymetal762:
I've got a CTS Aktiv buffer in both of my 308 guns and most of my 5.56 guns. They work, and make the action feel like it's on roller bearings. They are a no-shit-it-works upgrade.

ETA: my 308 guns are an 18" middy and a 16" middy. Both run noticeably better with the Aktiv.
View Quote
I use the mgi 7.1oz mechanical buffer with tubbs flatwire spring to solve my overgassed Bushmaster 16" mid (switched to armalite length tube). I think that AIM kit would work well and maybe pick up a tubbs flatwire later if it needs more slowing down.

Btw, my CBC 7.62x39 has been almost perfect (1 light primer strike) for over 500 rounds.
Link Posted: 8/22/2017 8:33:43 AM EST
Good to know CBC's x39 is working well for you. Hopefully my 308 will too.

OK, from what I've gathered from this thread:

I need a heavy buffer or an adjustable gas block or both.

How about this?

I buy This kit since I'll need all these parts anyways. Add my stock and I'll be in for around $100

And if I feel it's necessary I'll buy this Adjustable gas block Then I'll be completely in for around $150

That's about as cheap as I can go (I believe) to have both a slightly heavier buffer AND an adjustable gas block. That will leave me with only needing a good trigger. I've got my eyes on the 3# velocity trigger. I have one in an AR-15 and it seems to work and feel pretty good for the price.
Link Posted: 8/26/2017 3:14:36 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By heavymetal762:
I've got a CTS Aktiv buffer in both of my 308 guns and most of my 5.56 guns. They work, and make the action feel like it's on roller bearings. They are a no-shit-it-works upgrade.

ETA: my 308 guns are an 18" middy and a 16" middy. Both run noticeably better with the Aktiv.
View Quote
 One of their .308 carbine or rifle buffers? I'm considering one of their rifle buffers but see no weights mentioned on their website.
Link Posted: 8/26/2017 4:00:58 PM EST
[Last Edit: 8/26/2017 4:02:23 PM EST by bfoosh06]
Link Posted: 8/27/2017 1:27:37 AM EST
The Kaw Valley Precision 5.6oz kit I linked to above seems to work just fine with cheap 150 grain store bought SP ammo.

1.5" groups from a rest at 100 yards. 4 o'clock ejection. Bolt stays open on the last round.

At this point, I see no need for an adjustable gas block or heavier buffer/spring.

I may try to tighten up the groups some with Barnes TSX hand loads later on, but this will get me through this deer season.


swampie
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