AR Sponsor
Posted: 2/23/2017 1:17:17 PM EDT
|
I have an old (circa 1994) extension tube and A2 stock removed from an Olympic Arms 5.56 AR. The buffer is 4.8 oz and 6" long. The buffer tube is 9-5/8" deep and the spring is 12-3/4" long.
Is any of this suitable for use with an AR .308? I intend to install a fixed stock on my .308 build and wonder if, with adjustable gas, this tube/buffer/spring might work. What is the weight of a .308 buffer? TIA |
|
Quoted:
I have an old (circa 1994) extension tube and A2 stock removed from an Olympic Arms 5.56 AR. The buffer is 4.8 oz and 6" long. The buffer tube is 9-5/8" deep and the spring is 12-3/4" long. Is any of this suitable for use with an AR .308? I intend to install a fixed stock on my .308 build and wonder if, with adjustable gas, this tube/buffer/spring might work. What is the weight of a .308 buffer? TIA Only thing of use really is the RET (Receiver Extension Tube). Everything else is AR15-specific. You'll need an ArmaLite or DPMS .308 rifle buffer, which is shorter than an AR15 slightly, and an LR-308 or AR10 rifle action spring. |
|
I believe it is worth the $ in the case of a 308 AR with the issues so many seem to have.
Tubbs spring force I buy into his argument regarding extra spring force with a closed bolt without adding too much at the rear of the cycle (sending bolt back faster and breaking bolt catch or outrunning mag spring). A 308 rifle buffer would work fine. I considered a rifle re but the A2 stock on an lr308 has a lop a couple inches over an A2 ar15 so you should at least get an A1 stock. It seems unless you can afford a DD with its longer cam pin track to delay bolt unlocking, spring/buffer/adjustable gas is all we have to work with. The tubbs has mine running a few hundred rounds of surplus and some factory without a hiccup. I didn't bother with changing the gas block and a SLR, Syrac,etc. run $100. LaRue MBT, Weaver tac 2-10x36 - not bad for a budget 308 AR 
|
|
From my notes on AR-15 buffer tubes, I have:
Buffers weights Carbine: 2.9 oz Spike's T1: 3 oz H: 3.8 Spike's T2: 4.1 H2: 4.6 H3: 5.4 oz I'm shopping for an AR .308 buffer. Aero lists their .308 carbine buffer as a mere 3.8 oz - H buffer weight. I have read in lots of places, "Do not use an AR-15 buffer in a .308" and I've assumed that it's because an AR-15 buffer is too light. But then I see that Aero sells a .308 carbine buffer of just 3.8 oz -- lighter than what many run in their AR-15s. I have to assume that many people buy and successfully use the Aero buffer and spring in their builds. Now, I know that Heavy Buffers has a 10 oz SS buffer for .308 rifles. (And they say not to use flat wire springs with it!) So, I'm seeing a range of .308 buffer weights from 3.8 to 10 oz. What weight do most people run? At the start of this thread, I noted that I have a 4.6 oz buffer from an old AR-15 and was advised not to use it, So, what's the deal? Aero does not list the weight of their .308 rifle buffer but I assume it's at least 3.8 oz, and I'm stumped on what's an acceptable buffer weight for my rifle length extension tube. And is it okay to use a carbine length buffer in a rifle length extension tube? The buffer and spring are the last pieces I need to complete my build. |
|
Quoted:
hummm....interesting. i never knew the rifle buffers where different length. i've been using an ar15 a1 buffer tube, buffer and spring in my bushy orc carbine 308 forever without any trouble. the bolt travels past mag catch. I highly doubt you have an AR15 rifle buffer in that set-up. There is also no such animal as an A1 or A2 RET. They're the same length from the ones used on the Colt 601 (first production AR15/M16) to the M16A4, although there were differences for tool installation and removal. The A2 added a spacer at the end of the RET, between it and the butt plate assembly, with a longer screw to fasten the plate to the RET, captivating the stock against the rear of the lower. The SR25 was designed to use as many parts common to the AR15, particularly the buttstock, RET, and as much of the LPK as possible. The original AR10s used a much larger RET diameter. As a result, the SR25 BCG steps down in OD on the tail to fit inside an AR15 RET. Since the SR25 bolt carrier is longer, the buffer needed to be shorter in order to allow full BCG travel to the rear. |
|
Quoted:
I just heard back from Aero. I was told that the rifle .308 buffer is "about 5.6 oz" which is surprising, since their carbine .308 buffer is advertised as 3.8. Why the difference? Anyone actually weighed the Aero buffer(s)? You can't get 5.6 oz into a tiny carbine buffer unless you make the body from steel, and fill it with tungsten weights. The tiny AR10 buffers should never have been born. |
|
Quoted:
I highly doubt you have an AR15 rifle buffer in that set-up. Quoted:
I highly doubt you have an AR15 rifle buffer in that set-up. There is also no such animal as an A1 or A2 RET. They're the same length from the ones used on the Colt 601 (first production AR15/M16) to the M16A4, although there were differences for tool installation and removal.
The A2 added a spacer at the end of the RET, between it and the butt plate assembly, with a longer screw to fasten the plate to the RET, captivating the stock against the rear of the lower. The SR25 was designed to use as many parts common to the AR15, particularly the buttstock, RET, and as much of the LPK as possible.
. |
|
Quoted:
You can't get 5.6 oz into a tiny carbine buffer unless you make the body from steel, and fill it with tungsten weights. The tiny AR10 buffers should never have been born. The Big Question is: What should a .308 buffer weigh? (range) |
|
.308s are confusing because there are two common patterns, DPMS/lr-308 and Armalite/AR-10.
The length of both patterns rifle extension tubes are equal to each other, and equal to the AR-15. The rifle buffer length on both patterns is shorter than the AR-15 to accommodate the stroke of the longer .308 cartridge. If you tried to use an AR-15 rifle length buffer on a .308, the carrier would not be able to go far enough back to eject the shell and pick up a new cartridge. Now the really confusing part. DPMS/lr-308s and Armalite/AR-10s have two different patterns for their carbine models. Each one uses either the same length extension tube as the AR-15, or the same length buffer as the AR-15, but not both. The lr/308 carbine pattern uses the same length extension as the AR-15. It uses a shorter than AR-15 length buffer to accommodate the stroke of the longer .308 cartridge, similar to the rifle system described above. The AR-10 carbine pattern uses a longer than AR-15 extension tube. This extra length of the extension tube is what accommodates the stroke of the longer .308 cartridge. This allows the AR-10 to use the same length carbine buffer as the AR-15. Both pattern's rifle buffers have space for 5 buffer weights. AR-10 carbine buffers have 3 weights and are the same as AR-15 buffers (interchangeable). Lr-308 carbine buffers have only two weights. Both weights are usually tungsten so it is hard to add weight without going to a Slash type buffer. |
|
I have o break up my reply into two posts as my length is too long for a newbie. (stupid rule)
Quoted:
.308s are confusing because there are two common patterns... Quoted:
.308s are confusing because there are two common patterns... The length of both patterns rifle extension tubes are equal to each other, and equal to the AR-15. The rifle buffer length on both patterns is shorter than the AR-15 to accommodate the stroke of the longer .308 cartridge. If you tried to use an AR-15 rifle length buffer on a .308, the carrier would not be able to go far enough back to eject the shell and pick up a new cartridge. Continued in next post. |
|
Quoted:
Now the really confusing part. Quoted:
Now the really confusing part. DPMS/lr-308s and Armalite/AR-10s have two different patterns for their carbine models. Each one uses either the same length extension tube as the AR-15, or the same length buffer as the AR-15, but not both.
The lr/308 carbine pattern uses the same length extension as the AR-15. It uses a shorter than AR-15 length buffer to accommodate the stroke of the longer .308 cartridge, similar to the rifle system described above. <snip> Both pattern's rifle buffers have space for 5 buffer weights. AR-10 carbine buffers have 3 weights and are the same as AR-15 buffers (interchangeable).
Lr-308 carbine buffers have only two weights. Both weights are usually tungsten so it is hard to add weight without going to a Slash type buffer. Back to buffers and tubes for a DPMS pattern... My RET is 9" deep, almost 2" deeper than a collapsable stock RET you'd find on the typical AR-15. . It can accommodate a longer buffer -- which I thought was a rifle buffer of 6". That's what came out of my Oly. Nine inch deep tube, 6 inch long buffer. Back to my questions: What is the weight range for .308 buffers? What's typical? Is there any reason one cannot use a carbine .308 buffer in a deeper (9") RET? |
|
Quoted:
I have o break up my reply into two posts as my length is too long for a newbie. (stupid rule) Mine is DPMS. And what would that length be? And the inside depth? These would be handy. You seem to be saying that there is one and only one length for AR-15 buffer tubes, yet I have one that is 9 inches deep. It accommodates my A2 stock. That would seem to make sense, as long as you assume one and only one buffer tube depth. But the buffer would not need to be shorter if the RET depth were longer, which is what I have. Doubtless true, if you are talking about an approximately 7" RET depth. But I have a longer 9" depth. And, in any case, I'm not planning to use an AR rifle length buffer in my .308. It would seem to be too light, though I don't know what a normal .308 buffer weighs. Continued in next post. Quoted:
I have o break up my reply into two posts as my length is too long for a newbie. (stupid rule) Quoted:
.308s are confusing because there are two common patterns... The length of both patterns rifle extension tubes are equal to each other, and equal to the AR-15. The rifle buffer length on both patterns is shorter than the AR-15 to accommodate the stroke of the longer .308 cartridge. If you tried to use an AR-15 rifle length buffer on a .308, the carrier would not be able to go far enough back to eject the shell and pick up a new cartridge. Continued in next post. There are two sizes of buffer tubes for both the AR-15 and AR308s. They are called rifle and carbine. Rifle length extensions are the same for DPMS and Armalite and mil-spec AR-15s. You have a standard rifle length extension. You will need to use a standard .308 rifle length buffer. It will be shorter than an AR-15 rifle buffer. It is shorter because the .308 cartridge is longer than a .223 cartridge. |
|
Quoted:
As if I weren't confused enough already. I don't see why it could not use a longer RET and same length rifle buffer as an AR-15. Are you talking about JP Silent Captured Springs? JP SCS again, I assume. Back to buffers and tubes for a DPMS pattern... My RET is 9" deep, almost 2" deeper than a collapsable stock RET you'd find on the typical AR-15. . It can accommodate a longer buffer -- which I thought was a rifle buffer of 6". That's what came out of my Oly. Nine inch deep tube, 6 inch long buffer. Back to my questions: What is the weight range for .308 buffers? What's typical? Is there any reason one cannot use a carbine .308 buffer in a deeper (9") RET? Quoted:
Quoted:
Now the really confusing part. DPMS/lr-308s and Armalite/AR-10s have two different patterns for their carbine models. Each one uses either the same length extension tube as the AR-15, or the same length buffer as the AR-15, but not both.
The lr/308 carbine pattern uses the same length extension as the AR-15. It uses a shorter than AR-15 length buffer to accommodate the stroke of the longer .308 cartridge, similar to the rifle system described above. <snip> Both pattern's rifle buffers have space for 5 buffer weights. AR-10 carbine buffers have 3 weights and are the same as AR-15 buffers (interchangeable).
Lr-308 carbine buffers have only two weights. Both weights are usually tungsten so it is hard to add weight without going to a Slash type buffer. Back to buffers and tubes for a DPMS pattern... My RET is 9" deep, almost 2" deeper than a collapsable stock RET you'd find on the typical AR-15. . It can accommodate a longer buffer -- which I thought was a rifle buffer of 6". That's what came out of my Oly. Nine inch deep tube, 6 inch long buffer. Back to my questions: What is the weight range for .308 buffers? What's typical? Is there any reason one cannot use a carbine .308 buffer in a deeper (9") RET? If you take a standard buffer and remove the polymer tip, you will be able to remove the weights inside. The buffer you will need is 5-3/16" long and holds 5 weights. If you want a heavier buffer you simply remove 1 or more of the standard steel weights and replace them with tungsten weights. You can't use a carbine length buffer in a rifle length extension unless you put a spacer in and use a carbine spring. |
|
Having to reply in two parts again...
Quoted:
Reread my post slowly, I think you are overthinking this. Quoted:
Reread my post slowly, I think you are overthinking this. There are two sizes of buffer tubes for both the AR-15 and AR308s. They are called rifle and carbine. Rifle length extensions are the same for DPMS and Armalite and mil-spec AR-15s. You have a standard rifle length extension. You will need to use a standard .308 rifle length buffer. It will be shorter than an AR-15 rifle buffer. It is shorter because the .308 cartridge is longer than a .223 cartridge. There are no references to silent capture springs in any of my posts. Is this removing/swapping of weights universally true? That is, if I buy a 10 oz AR10R-XH from Heavy Buffers http://heavybuffers.com/ar10rifle.html, will I be able to fine tune by removing weights? Or would I be stuck with a 10 oz buffer? Is it acceptable to simply remove a weight and not replace it with another? Put another way, is it okay to let weights slam around inside the buffer? Or would one have to replace a removed weight with a spacer? Continued in next post... |
|
Continuing the reply above...
Quoted:
If you take a standard buffer and remove the polymer tip, you will be able to remove the weights inside. Quoted:
If you take a standard buffer and remove the polymer tip, you will be able to remove the weights inside. The buffer you will need is 5-3/16" long and holds 5 weights. If you want a heavier buffer you simply remove 1 or more of the standard steel weights and replace them with tungsten weights. You can't use a carbine length buffer in a rifle length extension unless you put a spacer in and use a carbine spring. Given the cost of the Heavy Buffer 10 oz unit plus a Tubb's flat spring, I'm already at the cost of a JP SCS for an AR .308 with the additional springs http://www.jprifles.com/buy.php?item=JPSCS2-10K And I already have spare tungsten weights for my other JP SCSs used on my other guns, so adjusting the JP SCS would be easy enough. And I am (apparently) vastly more familiar with the JP SCS than I am buffers. I think I'll just go with the JP SCS. Thanks to all those who constributed, especially Sencoman, for their insights and helping me reach this decision. |
AR Sponsor