So here's the deal:

I want to put a 10.5" upper (just went with Radical, because Primary Arms had them cheapo) on my AR. I will be mounting my 6" can to it permanently to get it over the 16" length, at least until I SBR this gun anyway.

So with that said - I have a run of the mill 16" upper right now, with run of the mill buffer spring, run of the mill buffer. Assume they are milspec, I really don't know to be honest - it was a CMMG bargain bin gun that I bought for fun several years back and am just now getting around to tinkering with.

From what I gather, it is wise to either put a stronger spring (opinions are mixed on that) to slow down the bolt, I want to put an adjustable gas block to control bolt speed better, and some folks recommend a heavy buffer.

What is the opinion of those that have traveled down this road already and have lived and learned through trial and error? This is not a gun I plan on assaulting Hamburger hill with - so I don't have a need to have parts made from titanium & kryptonite (or whatever the newest fad is) that can withstand any amount of abuse known to man - I want quality parts, but they don't need to be Green Beret/Navy Seal durable. It is a fun gun to shoot, that's about it really.

I run a standard carbine buffer and spring my 10.5".

No problems with it.

The Wonderer said:

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I run a standard carbine buffer and spring my 10.5".

No problems with it.

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+1 with an adjustable gas block.

ETA - in general, start with what you have. If it's not cycling or there is way too much blowback, then start tinkering. My 10.5 works just fine with and without the can. I have the block set to cycle just barely with the can on.

All three. I run gas block turned down to 1-1/2 turns, just open enough to cycle gun with weakest ammo. Also an H2 buffer. These have the gas issue corrected, but still pretty strong recoil impulse suppressed. It will take a lot of tinkering to get it right and be able to make reasonable double taps.

I would run a heavy buffer for maximum recoil reduction. Then run an adjustable gas block to dial in the gas.

Doing the same thing for with 10.5" but doing a pistol lower until I SBR it or the NFA gets blowed up. Whatever happens first.

I'm running DD fixed rear sight and an A2 gas block/front sight as this is going to be a truck gun so hoping I won't need an adjustable gas block. Guess if I need to turn the gas down when running suppressed that is easy enough with a new hand guard, adjustable gas block, and new fixed front sight.

I universally hate adjustable gas blocks. If you shoot your rifle enough (and most folks don't), they will come out of adjustment.

Also temp and ammo effect how a rifle functions. So unless you get traincar loads of the exact same ammo and have extensively tested your gas block setting with that ammo in all temp conditions (and it stays adjusted, big if) then it may not run when you need it too.

The answer you seek is an H buffer or a 9mm buffer. Standard spring.

I'm not a fan of adjustable gas blocks. There are some situations where one has to be used but if the barrel manufacturer did their R&D correctly, their gas port should be sized correctly to allow you to tune with a standard gas block. That said, there is no universal answer. For instance, I have 2 300blk, 1 has a 12" AAC barrel and requires an H2 buffer or it will out run itself, the other is 10" BA and requires a standard buffer or it won't cycle subs unsuppressed.

Do you get to BCS much? If so, bring it on your next trip. I have some springs and buffers (std, H2, H3) we can try to get it dialed in with so you're not out money on a bunch of trial and error.

My bigger question is how do you intend to permanently mount the can until you SBR?

I appreciate the offer skelso, but wont be up there with enough time to shoot anytime soon. No huge issue, buffers arent super expensive and i could probably test run one from some folks down here if it comes to that.

As far as permanently mounting, havent settled on specifics yet. There are lots of options available - the big key is making sure it is not able to be diassembled into components without the aid of something more than hands or normal tools. Pinning, welding, soldering, epoxies are all methods you can use.

For the can to the brake I will probably lean towards solder or a high strength/high heat epoxy because my suppressor is Ti. Will likely tack the brake to the barrel - easy to clean up and make look good and can be modified at some point down the road if necessary. I dont have a lot of plans of using this can on something else, mostly because i really dont have a rifle suppressor ready outside of this AR.

Sounds like you have thought it through.

Just an FYI, I was advised by my ATF inspector that ATF does not consider lock-tite (any version) and similar products to be "permanent" so I silver solder (ATF requires 1200 degree or better) them when necessary. That said, The chance of someone inspecting one I've worked on versus someone inspecting what you do to your own rifle are very different.

If you ever plan to SBR, don't use Rockset. Even with heat to break the bond, I've seen that stuff damage threads.

I'm building an 11.5" that will run mostly suppressed. My understanding from talking with micromoa, is I will be fine running suppressed with carbine action spring and carbine buffer, because I am controlling the pressure at the gas block- where the problem starts. If it was a FA gun, I would step up buffer weight to keep from bottoming out.

I couldn't remember if Loctite was considered permanent or not, glad you mentioned it. I'll probably just go with a solder in a couple of spots combined with some red loctite to back it up. Simple and easy and can be undone for whatever reason later down the road with some, but not excessive, effort.