I want to build a balanced (not front heavy) 11.5" that will reliably cycle suppressed and unsuppressed. I’d like to reduce the amount of wear to the action but I’d also rather not bother with an adjustable gas block. I’m looking at an a5 buffer tube but I’m unsure of buffer weight and spring strength. BCG will be BCM and bbl has a carbine length gas system unless there is a better combination to achieve what I’m looking for. Griffin 30sd suppressor. How would you build the softest shooting, most reliable ar in this configuration?
I would look into the Sionics 11.5 rgp barrel. It is .070 which should be good for mixed use. You may be able to go a little smaller which a gas block insert.
For the A5 buffer it depends on ammo and spring as well as the buffer weight. Probably be safe starting with an H2 and go up from there. Heavy buffers. Com sells an A5 buffer set that you can change the weights on
Biggest thing without an adjustable gas block is going to be the gas port size on the barrel. BCG is from BCM, will the barrel be as well?
Yes bcm barrel as well
Black River Tactical custom tune gas block would be worth looking into. You simply order the block with the gas port size you want. I have one and it works well.
I would buy a KAC 11.5”.
Edit: and nix the bcm bcg, obviously.
Second choice, buy a commando, cut down a 6920, or buy a bcm upper. 11.5” is pretty forgiving and a 30cal can should have minimal back pressure.
I’m not sure I understand what your main question is…it seems like you already have the main components for your build, the barrel being the most important. And you’ve already said you don’t want an adjustable gas block. So, if you already have an 11.5 BCM barrel, go with a BCM gas block. Better yet, just buy a factory 11.5 BCM URG. They build it much better than you or I could.
If there is any possibility of changing the barrel, I echo the gentleman above and also recommend the Sionics 11.5 with reduced gas port…paired with a standard Sionics or BCM gas block. I have 2…they work great suppressed and unsuppressed with multiple types/grains of ammo.
As for receiver extension, carbine and A5 will both be reliable depending on the spring and buffer choice. As stated above, simply start with an H2 and standard spring. If you get bolt lock back on an empty mag with all types of ammo both suppressed and unsuppressed, then try an H3. When last round lock back fails, you know where the failure point is (ie ammo type, suppressed vs unsuppressed, etc). I’ve seen plenty of guys who run an H2 when shooting unsuppressed, and when they toss on their can, they swap out for an H3. However, this is more practical for range work, but perhaps not patrol/mission oriented, unless you always carry an extra buffer in your kit. Although most folks will typically start and end their patrol/mission the same way, so just select the correct buffer for the job during pre-mission checks.
The same buffer weights typically apply to the A5 system, which also might give you a softer/smoother recoil impulse, although adding a bit of overall length to the weapon. So you just have to decide what is more important. Personally, I never fully collapse the stock unless I’m in a vehicle and cramped for space, and even then, I’ve never had an issue with the slight length increase of the A5. I am typically not a fan of using anything other than a standard buffer spring, whether in carbine or A5 length, respectively. However, mounds of data have been collected by experienced M4C members with the LMT enhanced carrier and specific Springco colors…but those are pretty much all in the name of a dedicated suppressed SBR. Not suitable for your purposes/intentions.
If your concern is more about balance, especially with a can and maybe some kind of laser/IR device out front, then toss on a Magpul UBR 2.0 stock, which works with either a carbine or A5 length extension. The rifle will be heavier, but it will balance better. I love the new UBR, and it is my new SOP for suppressed SBRs with heavy barrels, cans, lasers, and a LPVO. There’s just no other way to balance it better.
Finally, if you truly want the “softest shooting, most reliable” 11.5 AR, then ditch the build and buy a factory KAC SBR. Their bolt/barrel/gas system/buffer harmony is unmatched. I’d give a close 2nd to LMT (MLC if you like MLOK or CQB if you like quad rail), either a complete 11.5 SBR or just the URG with the enhanced bolt. Plus the added benefit of swapping a 12" piston barrel and BCG if you ever desire. The LMT CQB was the first SBR I ever purchased…others have come and gone, but it stays. It is heavier than others, but it never fails…suppressed, unsuppressed, match ammo, steel case/steel jacketed ammo, whatever. It works.
Back in the day, I would have also recommended factory Noveske SBRs/uppers, especially for their pinned gas blocks. I still love them, but I think they’ve been surpassed by others in both function and value.
Knights Mod 2 would be my pick
Only part I have so far that I’m sure of is a geissle 10" mk4. Open to all suggestions. Some guys from another forum suggested an 11.5" colt fbi barrel (.07 gas port), lmt enhanced carrier and geissle super 42 w/h3. Any input on that setup?
I would recommend a quality barrel + the BRT GB/GP insert + Vltor A5 system.
Many different options, just like cars, will work. LMT enhanced BCG, is great. But for what your looking for its hard to beat RGP 11.5 barrel from Sionics. Go with A5 buffer set up, for sure.
PB
I have currently one, and have had as many as 3 BCM 11.5 uppers. All ran suppressed/un-supressed with a factory gas block, carbine buffer spring and either an h1/h2 buffer. I also have a BA 11.3 hansen profile barrel that I run with a bootleg adjustable bcg that runs great as well.
My softest shooting gun is a suppressed 11.5" BCM with standard lightweight barrel (not ELW). Whenever friends shoot it they can’t believe how smooth it is. It’s 100% reliable suppressed and unsuppressed, with absolutely nothing special done to it. No adjustable gas block, and standard carbine spring with an H2. I’ve tried a Sprinco blue but can’t remember why I switched back. My can is a Silencerco Omega. I think shooting .223/5.56 out of a .30 caliber can also adds to the smoothness and lack of back pressure.
As others have said, if you have the bucks, the easy way to have probably the best one overall at this point in time, is to just buy a KAC 11.5”.
My softest shooting gun is a BCM 11.5 elw upper with an A5H3 and a gemtech ajustable bolt carrier.
Just know and I understand the why you want to run both with and without the can that you will be over gassed when suppressed. The gas port in both my 11.5 BCM barrels pins at .073 and I have been trying to smooth it out. With a BCM gas block, BCM BCG and H2 buffer and standard spring the rifle ran great with and without. I recently switched to the A5 tube with a LARB buffer which really smoothed it out and reduced the recoil impulse.
Running with an adjustable gas block set for my Omega by far has made the biggest difference and has me realizing that I cant have the best of both worlds.
I have two 11.5” carbines, both with Sionics barrels- one is the RGP that is run mostly suppressed it functions perfectly without a can as well. The other is the ERGP with a dedicated SOCCOM556-RC that, somewhat surprising, also cycles unsuppressed with .223-pressure ammo (Federal XM223SP1) though will not always lock back on empty. Both carbines use Colt BCG’s and Vltor A5H2 buffers with standard springs. The only thing I would change is perhaps to try LMT enhanced carriers in one or both.
Both run very smooth and are well-balanced with a KMR-A rail and Geissele SMR (respectively) and Magpul SL stocks. I primarily shoot the RGP with Saker556k but occasionally with an Omega (both in Key-Mo mounts), no issues with either.