The big 10.5"-12.5" general purpose pistol/SBR thread

The thread on Wolf Importing Steel Cased 300 Blackout got me to looking around for a thread like this and I really didn't see one, so here we are. If there's already one and I missed with by not using the right search string...well, here we are anyway.

After spending a month or so building an AR9 pistol in my head I started thinking about a rifle caliber pistol build. There is no best/perfect/one to rule them all because everyone has different wants and needs, I get that. I'd like this thread to be a place you can show and describe your pistol/SBR and explain why you put it together the way you did. Plus I'm going to mine it for ideas should I ever decide to quit overthinking what I want and just build one. ;)

Aaaaaand go! :D

I'm issued a Colt 933 (11.5" Commando), and despite its previous 15-18 years of front line use/abuse with no round count records and absolutely zero preventative maintenance, it kept on chugging. Some of our similar rifles were beginning to exhibit symptoms of wear so once I took over armorer duty I budgeted to refurb the oldest rifles. With the assistance of Wayne Dobbs (thanks again!) I re-sprung the lowers and replaced the uppers with complete BCM MCMR 11.5" uppers. I wish I could have budgeted for the BFH or ELW barrels, but all I could swing was standard chrome lined barrels.

The 933/BCM 11.5" combo has been very ammo tolerant and I've had no issues with them in service for a couple years now. Round counts aren't terrible- 1.5-3k/year, but the handling and environmental abuse are significant- banging around in cruisers and at calls. The guns continue to run well and I'm not chasing parts breakages anymore.

For personal use I have a Sionics pistol lower with a self-built upper using a BA Hanson 11.3" barrel and a Midwest combat rail hand guard. So far no complaints but I also don't have nearly the depth of experience as with the work gun. Not that it makes a huge difference, but the work guns are H1/standard buffer spring vs. personal is H2/Springco blue.

https://uploads.tapatalk-cdn.com/202...a9ab779643.jpg

Anderson lower, SBA3 brace, Adams Arms 11.5” piston upper, with a SIG Romeo5. Other highlights, MOE-K grip, KVP Linear Compensator, MBUS sights (Pro up front for heat with gas block), and a nickel-Boron trigger group. Might swap the trigger for a Fostech Echo II, if all good when it comes back from Fostech (C/S is awesome with them). Only difference from picture is actually have an ambidextrous selector, opposed to one that had stripped threads.

Comes out to just under 26”, which is a nice setup to have just leaving NJ. My new truck gun, so I set it up to be used if there ever was an active shooter or another type of threat when I’m not working. The Echo trigger would be a nice addition... if it functions 100%. SIG red dot is good enough for what I need, with the battery life I’d want in this role. I do have a LaRue mount on order for it, in case I ever had to pull it from the gun. TLR-1 is one of my standard lights, and running Gen 2 PMAGs in it (straight 20 is the one in the gun for profile sake).

I wanted to stick in the over 10” range, mainly for velocity. I run two types of ammo; Hornady Critical Defense (73 grain) and M855. Hornady is in the gun, and have a four magazine pouch holding two Hornady and two M855. Also tossed an extra magazine of each in the center console. My theory... CD does well out of short barrels ballistically. Not too sure on hard barrier penetration, which I am sure on M855. If CD works well through barriers, I’ll dump M855 and go all Hornady... but too early to tell.

I considered a 9mm pistol, and probably will get a CMMG Banshee when we move over to Glocks... but only benefit is magazine compatibility and less noise. Personally, I rather a rifle round over a pistol round... but both likely would work.

Years ago (early - mid 2000's) I carried a 10.5" LMT upper/ Colt M16 lower combo at work for awhile. Ran like a raped ape, no issues.

https://pbase.com/kwb377/image/54652552.jpg


About ten years ago I SBR'ed my personal 6920 to 14.5"...then a couple years later installed a BCM 11.5" BFH barrel w/ DD BCG and a Brownell's lo-pro gas block. I put several thousand rounds through it with no issues.

https://pbase.com/kwb377/image/144245926.jpg



This past summer I put the barrel and a BCM gas block into a BCM upper, then bought a BCM lower and built as a pistol. I've got a couple thousand rounds through it now with no issues.

https://pbase.com/kwb377/image/170264177.jpg



About a month ago, I bought a Ruger AR-556 10.5" pistol and installed a Law tactical folder. I've only got @ 1k rounds through it so far, no issues.

https://pbase.com/kwb377/image/170264179.jpg


I've had zero functioning issues with any of them. The only preventative maintenance I've done has been replace the gas rings in the Colt a few years ago and an H2 buffer with new spring in it a few months ago.

My 11.5" guns are the only ones that get shot anymore. My 16" collects dust.

My favorite 11.5" is my Colt 6933. I've had it the longest and have the most rounds through it. It's been dead nuts reliable and the only thing I've done to it is replace the gas rings at 5000 round intervals. I was going to chop the FSB and install the Geissele Fed rail I bought last year on Black Friday, but I'm gonna chop the rail for the FSB.

My other 11.5" is a BCM MCMR. It's been nothing but boringly reliable as well.

I built another with a Spike's CHF barrel that's made by FN on an Aero stripped upper and a Colt BCG. I let my wife shoot that one or friends that I take shooting. It's over gassed in comparison to the Colt and BCM but it's been reliable as well. It's the least accurate of the 3 11.5" barrels that I have.

I find 11.5" to be the perfect length for me and my needs/wants/larping requirements. A Law folder makes it a great travel gun and fits my Vertx Gamut Plus perfectly.

I have two 11.5” 5.56 AR pistols. I have no desire to go shorter in 5.56. But for a 300BO is there a “Goldilocks” length for a 300BO AR with and without a suppressor?

Here’s the work 933:
Attachment 47100

Regarding uppers, let’s use my favorite as a base. BCM 14.5” midlength gas, ELW profile, pinned A2X. This is IMO the sweet spot for a non-NFA do-everything “you can only have one gun” weapon. Fortunately this is America and I can have more than one gun.

Aero upper, gov profile 12.5” barrel, carbine gas, Atlas R-One handguard, YHM Phantom flash hider: due to the gov profile, this is only 2 oz lighter and the only benefit is being 2” shorter - while still being restricted to all the ‘pistol’ BS. That said, I do like it, and don’t plan to sell or trade it. After zeroing at 25 yds, I haven’t attempted to see just how accurate it can be beyond that. It’s been boringly reliable and accurate enough to ring 8” steel plates all day long at 100 yds with an MRO and XM193. For my purposes, it’s fine. And not only fine, I like it very much. I know the YHM flash hider isn’t cool anymore, I just happened to have it. Also runs frangible 5.56 equally well, I used that on some closer drills.

LaRue 12” Ultimate Upper (Stealth barrel): I took off the Tranquilo brake (not a brake fan) and just put an A2 on it. With that, the whole upper setup is 5 oz heavier than the BCM. Again, I haven’t pushed the accuracy but this feels like something you could take to war. It’s solid. And likewise runs XM193 with no issues. I love the upper, it’s solid and well-made, but IMO this would probably be better in a scoped 16+” platform just because of the weight. Being heavier defeats the purpose of going shorter, but it is a very good product. Balances better with the SBA4 brace, vs the lighter SBA3.

BCM 11.5” ELW, MCMR 10” rail, Surefire 3P flash hider: this is not only 3” (obviously) shorter than the 14.5 but it’s 6 oz lighter (probably 7 if you ran an A2). Haven’t shot it yet, but I expect no issues. Handles extremely well. Going shorter with the ELW barrel makes for a very light, compact platform. Looking forward to running drills with this and comparing it to the 14.5” version.

Standard springs and buffers on everything, I don’t have time to dick around with tuning everything. Fortunately everything has run perfectly fine so far with no adjustments necessary.

And if anyone cares, I run Phase 5 straps on my braces because they add a small bit of stiffness...and they look cool which doesn’t hurt.

I have a pair of “big pin” 6933 factory SBRs. They haven’t been shot in a great long while but when they did I never had an issue. One is a dedicated suppressor host, the other is a dedicated ultralight. I think when I got mine you could just about only get them from Clyde Armory, if memory serves? Maybe it was someone else. They specialized in Colt parts when you couldn’t get them anywhere else, and I think the owner taught Armorer courses and was wideLy regarded as the Colt SME?

https://i.imgur.com/bjbeJtP.jpg

Top is an 11.5" DSG Duty grade upper; bottom is 11.5" Aero upper. Not a ton of rounds through them yet but no issues so far.