For now, until we get a court ruling that shoves the impending brace-ban back up ATF’s craplocker–for “discreet applications” I actually prefer the old fixed SBM4 over the adjustables because it can be turned into an onboard mag carrier with no added space cost, which you can’t do with the adjustables because of the track and latch hardware.
Still wish I could find someone to develop a locking hinge coupler that’d work around the QRB with “pull back to unlock/flip/pull back and latch to lock” rather than still having to fut with “manual unlock then manual join”–the game here is to shave seconds off deployment time as much as possible.
Since the barrel extension needs to enter the receiver in a straight path that seems unlikely without a complicated—and therefore bulky, heavy, expensive, or fragile—mechanism. But please prove me wrong.
Concept was you pull the entire front-end assembly about an inch toward you to unlock, which then as it flips puts the BE an inch forward, then pull the assembly backward sliding BE into receiver–ideally this would make the QRB latches there “just to make sure.”
The QRB itself would be unchanged, just that the current hard-dock “storage only” rail-to-rail coupler would evolve into something more like Vera from Firefly. That’s for another day, though, the entire purpose of this one was a quick-and-cheap proof of concept on “join the pieces into one for grab-and-run with minimal impact on deployment time.”
Barrel has arrived, BCG ripped out to preserve “mechanically incomplete” status. Remaining to-do:[ul]
[li]Have pro smith chop alignment tabs
[/li][li]Have pro smith torque and time QRB star nut, HG mount nut and flash hider
[/li][li]Pin gas tube
[/li][li]Source and install CR2016 and 1/3N batteries for light and laser
[/li][li]Source and install M-LOK rail section to mount Lasermax tapeswitch
[/li][li]Find Lasermax zeroing allen-wrench in the crap-pile of my storage unit
[/li][li]
[/li][/ul]
Sling is a cheap airsoft 2-to-1 off Amazon meant only for “range/inert trials”–were I actually writing up the PIP partslist for USAF Armament Shop I would be recommending something like the BFG Vickers 221 or similar convertible. Lasermax unit is set so it fires through a hole in the Damage Industries slingmount/handstop.
Disciple, since you specifically asked about this, based on pre-cut lengths once it’s all snugged down and finished the front of the rail should be about 3/16 to 1/4" behind the barrel shoulder on a 12.5".
Off the top of my head I don’t know added weight, lemme rustle up some tools and get back to ya. Could be a bit.
Updates: While I had WANTED to hold-out the BCG as a token “last step” for while my FFL and gunsmithing mentor watch*, Dickslee forced my hand with the HB1240 ban so I shoved that in along with a Damage Industries pistol tube–the kind that’s rounded around the rear edge and has a QD socket so it’s “distinctly not shoulderable.” It’s mechanically ready to test fire, but not ready to zero until I can get D&M to return my calls/emails (they were slammed with the pre-1240 beat-the-ban rush) and see about cutting down the alignment tabs on the handguards. The MI Lightweight Combat Rail right now rests on its barrel nut, it’ll protect your hand from the hot barrel but it won’t hold alignment to use the sights and whatever you do DON’T apply any forward pressure on it. It’s still ready to centerpunch any meth-head that forces his way past my door though…
*This was a standard practice for me, they liked to be “present at the creation” when I put the finishing touches on a build and declared it ready for use. The ASDW and the 007 Briefcase Charger are the only two builds in many years I haven’t done that with, due to Exigent Circumstances. Right now other than finishing our M16A4 and C7A2 uppers, further builds are on hold while the “fun fund” replenishes… and then I have to hope that either the courts strike down 1240 or after King Jay the Worst is out I can get a Longslide 1911 I doodled out back in college moving before our Rumored Pederast Attorney General comes back to double down for Round 2.
Pro Tip to all the scumbags out in the world: That heavy metal storm door with the heavy duty locks isn’t here to protect me from you. It’s here to protect YOU from ME, because once you breach it All Bets Are Off.
LOL, no please don’t pull it all apart just to weight it. But thanks if that’s what you meant.
The DI pistol tube is interesting but 6061 concerns me a little. Maybe not a problem on a pistol. I could see the QD socket stripping out with hard use though.
With any luck the DI tube won’t be needed for long, it only needs to last long enough for Asshat Terrorist Fascists to get bent over and bitchraped in the courtroom.
I WAS gonna say separating barrel, QRB and upper should be easy since I only hand-tightened the barrel nut… then I remembered the QRB star-nut (shorter barrel-nut) requires a barrel nut wrench and mine’s in the storage unit two hours away. If I had all my tools over here it’d be five minutes tops combined dis- and re-assembly.
I have to ask for your indulgence after all: please do weigh the system when you have time & tools. I have looked high and low and I cannot find any measurement of the weight the QRB adds. I almost cannot believe that none of the reviews and promotions mention this; do they make you sign a NDA or something? :rolleyes:
Honestly not sure if you mean this tongue in cheek or not. Where do I find the weight of the same configuration, handguard, sights, etc., without the QRB?
Do you have a 12.5" “standard” wafflestock build with MBUS sights? If so, take the handguard off and weigh the rest of it, I’ll weigh the MI handguard and then we subtract that total from 6.4. Pretty much any Government-profile 12.5 should do as a stand-in, gas tubes and lo-pro blocks shouldn’t differ that much. The MBUS sights weigh almost nothing. (Not being flip, trying to crutch you to an answer because of yet another case of my mother’s self-inflicted injuries keeping me stuck closer to home until whatever she pulled or twisted is back to normal. I swear she does this shit on purpose, because it happens like clockwork whenever I start making headway on things…)
As loath as I am to do “tacticool” like SI, that might be worth a look if the DI doesn’t hold up or the courts don’t go our way. If they do, however, back to CAR tube and SBA3/SBA4…
No, I have nothing like that unfortunately. I see where you were going with that now however. If you would weigh your upper receiver with that half of the QRB, and the barrel assembly without the handguard, I’ll go through the AR Parts Weight spreadsheet and add up the rest of the components to find the difference.
Will do, but the barrel weight is going to be “contaminated” by both the QRB frontplate and the MI mount nut, both locked in by the gas block. (Sorry, it was enough nightmare getting that damn thing on the first time, I paid the extra for drilling and pinning and got “drill but no pin.” Fighting with gas blocks… I think that stays on the “Subcontract to Pro” list.)
The complete CRLW-10.5 with nut I used weighs 7.6oz. Barrel is 22oz.
With barrel nut, frontplate and flash hider the barrel weighs 35.16oz. 35.16 - 22 = 13.16oz combined weight of A2 FH/crush washer, MI nut and QRB frontend.
BCG and CH removed but MBUS3 still on, the backplate and upper assembly weigh 12.13oz.
Test-fitting an idea I just had… thinking about dumping the weight and inflexibility of the A3 Tactical rail-to-rail clamp by just asking my pro smith if he can directly braze the ends of two QD optic-risers together for a closer coupling between the halves for both this and the “Bond Movie Briefcase.”
If I had all my tools over here it’d be five minutes tops combined dis- and re-assembly.