So, as my entry into the LR308 world, I purchased a complete Ballistic Advantage BA10 build. It’s an 18” heavy profile build with a rifle length gas system. Additions include a Spikes Tactical R2 brake, AAT adjustable (2-6pd) flat trigger, Aero Precision adjustable gas block, and a Vortex 4-16x44 Diamondback Tactical FFP in a Burris AR-PERP mount. I have a FAB Defense RAPS stock coming to replace the STR that’s on it. (The STR will probably end up on the wife’s LWRC).

All that said, I had an issue with some 168g Hornady Black ammo that lead me to check out my buffer. The rifle currently has a standard, 3oz-3.25” oal, carbine buffer. The spring is 10” long (the other ar15s in the house all have 10.5” springs). After some reading, the spring might be too short and the buffer might be too long and is definitely too light.

I’m currently thinking of going H2 and been looking at different combos. So, is the 3.25 oal buffer too long? All the ar15s in the house have that length, but my reading says for the LR308, the buffer should 2.5” or so. And the spring should be over 11”. Ballistic Advantage’s website says the complete BA10 lower will have a mil spec 308 carbine buffer and spring, obviously the previous owner changed them.

Anyway, educate me and give me some recommendations!

If you have an adjustable gas block, there is zero reason to worry about or mess with buffer weights. Get the lightest buffer you can and adjust the cycling at the gas block.

As far as getting the right length spring/buffer/tube, definitely address that. The combos all confused the hell out of me so I just got a carbine length tube and standard weight JP SCS, plug and play.

ETA what kind of issues did you run into and was it only with the Hornady ammo? If the buffer is too short, you’ll get damage on the bolt carrier and/or the lower receiver from the carrier being allowed to travel too far. If the buffer is too long you’ll likely run into short stroking issues.

2.5" buffer is used with an AR-15 carbine buffer tube, inside depth of 7".  I use this with Slash's Heavy Buffer 308 carbine buffer spring.  I guess you could use a run-of-the-mill AR-10 308 carbine spring, not sure.

3.25" buffer is used with a carbine buffer tube that has an inside depth of 7-3/4".  I think it's referred to as the A5 buffer tube, not sure, since I don't use this combo.

I don't have a RAPS stock to verify, but the check riser might interfere with the charging handle being able to be pulled all the way back when using the AR-15 carbine length receiver extension/308 carbine buffer (2.5")/308 carbine spring action system. I do not know that there would be a problem, but it is something that I would verify before investing in any parts. You may be forced to use an intermediate (A5) or rifle length RE and appropriate buffer/spring. I believe the RAPS can use all three length RE's, but verify.
Unless I was tuning the gas for a narrow range of ammo power, I prefer the heavier buffers. Mid 5oz for the 308 carbine buffers. For intermediate (A5) length RE's, I do the same as KAC, LMT. ArmaLite, Noveske and some others do, H2 or H3.

Definitely have the wrong buffer, so I’m going to address that.

I’ve shot the 168g Hornady and 147g Monarch steel through the gun. Only issues with the Monarch were a few FTF that I chalked up to the lacquer. With the Hornady, I had one primer completely blown out and another with the anvil showing. There were extractor and ejector marks on the cases after.

https://www.thehighroad.org/index.php?attachments/1ec44434-185b-4dc9-8359-8ea123055b15-jpeg.1093176/

https://www.thehighroad.org/index.php?attachments/70ade6c9-cfb2-4b31-a965-5e70bed9a570-jpeg.1093179/

I have not seen anything about the charging handle/cheek riser clearance issue, but will definitely report back when it’s on the rifle.


I’m thinking h2 or h3, then fine tune using the gas block. But I want it to run using a variety until I either find a favorite or start reloading my own.

H2 and H3 are terms that are only used for AR-15 carbine buffers (3.25"). 308 carbine buffers (2.5") are described by their actual weight. Conflating the two will only add to the confusion. If you intend on using an H2 or H3, make sure that you have an intermediate (A5) length RE, which are 7.75" inside depth as posted above. Once you have decided which action/recoil system length that you are going with, we can recommend specific buffers and springs if wanted.

Understood!

My problem now lies in the fact I’ve only shot this with a lighter than supposed to be 3oz buffer. I’m not certain the standard 3.7oz would be enough. This rifle’s main purpose is going to be ringing steel, maybe popping hogs at some point. So, I don’t know if I should be looking at 4ish or 5ish oz buffers to start, with the appropriate spring.

both of my AR10s run Armalite buffer tubes with a 7 3/4'' inside depth with a Tubbs flat wire spring. both buffers are 3.25'' long and weigh 5.4oz (H3 weight) and both rifles run VG6 epsilon brakes and both are very soft shooting. you need to measure the inside depth of your buffer tube, if it has a 7'' depth it's a standard AR15 buffer tube, and you need the 2.5'' short buffers like DPMS and Aero precision use. I would recommend you measure first and figure out what you need and if it is the short one go to KAK industries and buy their short 5.3oz buffer. also check out this 308AR forum for more compatibility issues.

if you have the 7" AR-15 carbine buffer tube, Primary Arms has a 5.3oz 2.5" OAL buffer that I've used successfully, interchangeably with the KAK version.  Good price, good quality.  it's their Expo Arms house brand.


OBTW, https://www.ar15.com/forums/general/Picture_posting_tutorial_and_PICTURE_test_thread/168-638569/?

Already measured, thought I posted it, guess I didn’t, lol. It is 7”. So it’s the short one for me.

From the responses so far, ~5oz is where I need to be.

The standard weight JP SCS for the ar10 is 5oz

Have you adjusted the gas block at all? It sounds like you’ve got too much gas and too light of a buffer (that’s also short stroking .75”, that’s likely your FTF issue). Turn the gas all the way off so the gun won’t cycle. Are you still seeing pressure signs? If so, your buffer weight isn’t the issue.

I wouldn’t do anything until you get the proper length buffer and see if that doesn’t solve some or all of your problems.

Start with a proper 308 buffer and spring.  Go from there.  Do not change too many things at once or you will be chasing your tail.

I haven’t touched the gas block yet. As you say in your last statement, I’m not going to do anything until I get the proper buffer and spring.


Speaking of, and the fact you mention the JP SCS, I’ve been looking at this, Armaspec AR-10 Sound Mitigation Buffer - Gen 3, comes in at 4.7oz. Thoughts? It’s overall
weight is 1.5oz less than the JP, and it gets good reviews.

RAPS stock in and on, along with a Gradus grip. The stock is solid, no movement and easy to adjust. There is also no clearance issues with the cheek riser / charging handle. The grip is a little narrower through the web of the hand, but feels great in the palm.

I’ve also installed the Armaspec captured buffer spring mentioned above, it has an effective weight of 4.7 oz. You can feel, and hear, the difference.

This weekend I hope you get it to the range and see what happens.

Also added a Alien Armory Tactical adjustable flat faced trigger. It’s currently breaking at a consistent 1.8 lbs.

.

i still can't see shit.

https://www.ar15.com/forums/general/Picture_posting_tutorial_and_PICTURE_test_thread/168-638569/?

I even tried looking at the pics on thehighroad.org, still can't see shit, access blocked or some silly shit.

you asked for recommendations:  I recommend you use imgur to host your pics.

Lol…sorry about that. The link works for me, but I’ll upload them elsewhere…also haven’t hit that 50 post count either.

Well, the buffer worked. Both 150 and 168 functioned fine, with ejection right at 3. There were a few that went a little forward, but not many. Accuracy was also improved. All in all, a great day.


Loved the new stock, grip and trigger as well. Now to get some bags and really wring some accuracy out of this thing.

Tubbs flatwire 308 spring and an H3 buffer.  If your rifle cycles manually with a 3.25" carbine buffer, it's not too long.  There is no "milspec" for AR10 - especially not LR308.

LR308 buffer:
AR-15 tube - 2.5" short buffer

Armalite 308 tube or A5 - AR-15 3.25" buffer (this is probably what you have)

AR15 rifle tube - 308 rifle buffer 5.25"