First 308 Build Newbie Needing Guidance (Buffer Tube)

[daiuskejigen]

I know this topic has been discussed here plenty, however I can't seem to properly grasp everything. My question is can I use a standard rifle a2 buffer tube  https://www.primaryarms.com/expo-arms-a2-rifle-length-buffer-tube with a h3 carbine buffer https://www.primaryarms.com/noveske-rifleworks-ar-15-carbine-buffer-h3-5-4oz Would I need rifle length 308 buffer spring? I've heard standard carbine buffer tube with orange Sprinco and lr308 buffer is a working setup but would prefer rifle stock vs collapsible. This is all on M5 Aero setup with criterion barrel 16" rifle length gas.

[Matt.Cross]

On 7/18/2022 at 1:13 PM, daiuskejigen said:

I know this topic has been discussed here plenty, however I can't seem to properly grasp everything. My question is can I use a standard rifle a2 buffer tube  https://www.primaryarms.com/expo-arms-a2-rifle-length-buffer-tube with a h3 carbine buffer https://www.primaryarms.com/noveske-rifleworks-ar-15-carbine-buffer-h3-5-4oz Would I need rifle length 308 buffer spring? I've heard standard carbine buffer tube with orange Sprinco and lr308 buffer is a working setup but would prefer rifle stock vs collapsible. This is all on M5 Aero setup with criterion barrel 16" rifle length gas.

The possible issue I see, is that the carbine buffer will allow more rearward travel of the BCG than a standard length buffer.  This could allow your BCG to chew your receiver up at the buffer tube threads.

[daiuskejigen]

Ah thank you! What setup would work best? I'm eventually going to run this suppressed.

[shooterrex]

https://www.armalite.com/SACItem.aspx?Item=AR10REKIT02&ReturnURL=/Armalite/Product-Category/AR10-Parts-Accessories&Category=4eeff98b-d9a6-40fd-be6b-ab2e44ec1080

These parts work.

[daiuskejigen]

shooterrex thank you for your reply I have read a lot of your feedback with other peoples issues! So this is a stupid question but is that the same length as standard a2 rifle buffer tube? The reason I ask is because I have the tube already can I use the one I have and just buy rifle length armalite buffer?

[shooterrex]

I have never measured one. I know the buffer is slightly shorter than an AR-15 buffer. You would also need the proper spring.

I do think the rifle length buffer tubes are the same for both platforms but don't know for sure.

Be careful. Spare parts turn into entire guns.

[Matt.Cross]

On 7/18/2022 at 1:50 PM, daiuskejigen said:

shooterrex thank you for your reply I have read a lot of your feedback with other peoples issues! So this is a stupid question but is that the same length as standard a2 rifle buffer tube? The reason I ask is because I have the tube already can I use the one I have and just buy rifle length armalite buffer?

Yes, you can use the buffer tube you have. Definitely buy the Armalite buffer and spring together, from Armalite if possible. If not, get what you need from Clint @ heavybuffers.com and you'll be set.

[daiuskejigen]

Much obliged guys! I read on here somewhere that using a rifle length buffer tube and standard h3 buffer is a good setup because of the availability of common ar15 buffers. This definitely has been a challenging build compared to 5.56

[Matt.Cross]

On 7/18/2022 at 2:06 PM, daiuskejigen said:

Much obliged guys! I read on here somewhere that using a rifle length buffer tube and standard h3 buffer is a good setup because of the availability of common ar15 buffers. This definitely has been a challenging build compared to 5.56

It's a pretty common trope around here to lament the lack of a unifying standard for large ARs as compared to their small frame counterparts. It's a completely different animal and it's not uncommon to learn that the hard way. At least you found the means to get your issues sorted out quickly & correctly.

[98Z5V]

18 minutes ago, daiuskejigen said:

Much obliged guys! I read on here somewhere that using a rifle length buffer tube and standard h3 buffer is a good setup because of the availability of common ar15 buffers. This definitely has been a challenging build compared to 5.56

A rifle receiver extension is 9 11/16th" deep.  On a .308AR, a rifle buffer is 5.200" long.  The AR15 rifle buffer is 5.900" long.  The AR15 Carbine H3 buffer is 3.250" long.

You cannot use an AR15 rifle buffer, it's too long.  You cannot use an AR15 Carbine buffer, it's too short.  It will physically fit, and you will slam the hell out of your lower receiver, with the BCG, the first time you fire it.

Edited July 18, 2022 by 98Z5V

[daiuskejigen]

98z5v I'm VERY happy you replied as well! I read several of your replies on other posts as well including information on gas tubes. So let me see if i have this right would either of these options work?

 

standard AR15 buffer tube with a special shortened buffer

or

armalite a5 carbine buffer tube at 7-5/8" with 3-1/4 heavy buffer 

[daiuskejigen]

98z5v I believe I read somewhere you stated the short 308 buffers were not good setup to run and 5oz buffers were the way to go. I believe I'm over complicating things. Just want to try and do everything right the first time. Goal is to have lightweight 16" 308 suppressed with rifle stock instead of collapsible.  If its as simple as ordering this https://www.armalite.com/SACItem.aspx?Item=AR10REKIT02&ReturnURL=/Armalite/Product-Category/AR10-Parts-Accessories&Category=4eeff98b-d9a6-40fd-be6b-ab2e44ec1080 I will def go that route. Just figured the standard ar15 buffers are plentiful and lots of weight combinations for when I add suppressor

[Matt.Cross]

On 7/18/2022 at 2:48 PM, daiuskejigen said:

98z5v I believe I read somewhere you stated the short 308 buffers were not good setup to run and 5oz buffers were the way to go. I believe I'm over complicating things. Just want to try and do everything right the first time. Goal is to have lightweight 16" 308 suppressed with rifle stock instead of collapsible.  If its as simple as ordering this https://www.armalite.com/SACItem.aspx?Item=AR10REKIT02&ReturnURL=/Armalite/Product-Category/AR10-Parts-Accessories&Category=4eeff98b-d9a6-40fd-be6b-ab2e44ec1080 I will def go that route. Just figured the standard ar15 buffers are plentiful and lots of weight combinations for when I add suppressor

You don't want to throw ANYTHING from an AR-15 into this platform. Nothing. You might get away with the trigger group, maybe. Don't put an AR-15 buffer in a large AR, period. 

Or... 

Run with scissors and document the results so we can all have a good belly laugh about it later.

[daiuskejigen]

The trigger group I planned on using is this https://cmctriggers.com/product/cmc-ar15-ar10-trigger-group-single-stage-cct-3-5lb-pull-small-pin/

Wanted flat trigger but they were out of stock. I will definitely heed everyone's advice. Anything else I should be aware of? Still have to order rifle length gas tube hopefully everything lines up.

[dpete]

1 hour ago, Matt.Cross said:

You don't want to throw ANYTHING from an AR-15 into this platform. Nothing. You might get away with the trigger group, maybe. Don't put an AR-15 buffer in a large AR, period. 

Or... 

Run with scissors and document the results so we can all have a good belly laugh about it later.

^^^ This right here!        Put this kit in it and be done!    https://www.armalite.com/SACItem.aspx?Item=AR10REKIT02&ReturnURL=/Armalite/Product-Category/AR10-Parts-Accessories&Category=4eeff98b-d9a6-40fd-be6b-ab2e44ec1080

[98Z5V]

10 hours ago, daiuskejigen said:

armalite a5 carbine buffer tube at 7-5/8" with 3-1/4 heavy buffer 

Armalite AR-10 Carbine receiver extension is indeed 7 5/8" internal depth, and it does take carbine buffers that are 3.250" long.  You want to make absolutely sure that the buffer is H3 weighted, at 5.4oz.  The recoil spring is the Armalite EA1095 spring.  Those are the exact parts that are in the kit that @dpete linked above.

[daiuskejigen]

Awesome I placed the order. Thanks for all the help. Now to just wait on the last few parts.