Dueling 12.5's - build planning, ersatz-GL/SSC vs GAU-5 ASDW

[Disciple]

With barrel nut, frontplate and flash hider the barrel weighs 35.16oz.

BCG and CH removed but MBUS3 still on, the backplate and upper assembly weigh 12.13oz.

Thank you. Please tell me if any of this looks off.

8.35oz Aero Precision APAR501603AC assembled upper
1.06oz MBUS3 REAR
2.72oz QRB backplate

1.7oz MI CR/SLH steel barrel nut -- may include 0.2oz torque plate and/or screws
21.8oz Rosco Bloodline 12.5” 5.56 NATO
0.85oz Rosco gas tube (other carbine gas tubes listed at 0.6oz)
1.9 to 2.15 oz A2 flash hider
1.5 to 2.5 oz Rosco 0.750 gas block -- no reasonable weight listed, estimated range
6.2 to 7.9 oz QRB frontplate

Total 2-pin QRB weight: 8.9 to 10.6 oz.

[Diamondback]

Looks like a pretty fair estimate--bear in mind the QRB also uses a proprietary 2-piece gas tube. But about 1/2lb feels about right.

[Diamondback]

Bump with a final update: It. Is. Done. Upper freshly back from a gunsmith tuneup.

[JediGuy]

Are the accessories on the bottom and top rails clone-specific?

[Diamondback]

Are the accessories on the bottom and top rails clone-specific?

No, they are completely my own, part of a "Product Improvement Program" concept. (Since I couldn't get the G2 rail for a true clone, I went for "how would the USAF build more if needed, and how can we make that better.") The top is just a coupler to join the two pieces together in the bag--doesn't make sense to have to fumble for six pieces in your seat-pan when seconds count in Indian Country if we can try to get it to "grab the rifle and a mag-carrier and RUN, decouple and set up once you've bought distance or other breathing room"--and a Princeton Tec Switch Rail dual mode red/white light. Bottom is a Damage Industries handstop/sling mount with a Lasermax Uni-Max set up to fire through it and a Lasermax tape-switch. I was trying for "rugged but lightweight and compact" additions to improve on the original model while hopefully still ejection-survivable. Spec is Magpul MBUS Pro sights; I upgraded to MBUS 3. (The 10-round mag in the well is not regulation either, but seemed a logical way to achieve a faster time-to-first-shot over having to futz with a mag on top of joining the barrel--this is "lock barrel, rack bolt, safety off, BANG." Safety-off can be skipped if it's packed hammer-down.)

Standard ASDW doesn't have a sling either, as far as I've seen, part of why I went with a 2-to-1 convertible. I have four possible mount points: the end of the Damage Industries buffer tube, the PWS ratcheting endplate, just ahead of the QRB on the Midwest handguard and the handstop at the very front.

[Disciple]

No, they are completely my own, part of a "Product Improvement Program" concept. (Since I couldn't get the G2 rail for a true clone, I went for "how would the USAF build more if needed, and how can we make that better.") The top is just a coupler to join the two pieces together in the bag--doesn't make sense to have to fumble for six pieces in your seat-pan

You mentioned the idea of a folding mechanism earlier. What do you think of the design of the FoldAR that does just that? If it returns to zero after folding it looks like the next evolution of this concept. In addition to keeping the halves together and aligned it is shorter as the upper receiver ends right after pivot pin, and I would bet the built-in mechanism is significantly lighter than an add-on. (The site lists 6.4 lbs for the 12.5" but 6.15 for the 16" so I don't trust their numbers.)

[Diamondback]

You mentioned the idea of a folding mechanism earlier. What do you think of the design of the FoldAR that does just that? If it returns to zero after folding it looks like the next evolution of this concept. In addition to keeping the halves together and aligned it is shorter as the upper receiver ends right after pivot pin, and I would bet the built-in mechanism is significantly lighter than an add-on. (The site lists 6.4 lbs for the 12.5" but 6.15 for the 16" so I don't trust their numbers.)

Were *I* designing from a clean sheet, the FoldAR is more like the direction I would have wanted to go in. However, an ejection is an absolutely brutal experience--per my prof if you have to ride the bangseat you WILL be coming out of it with at least minor-nuisance level injuries--so it would need to be tested for shock tolerance. I'd also assume that USAF Gunsmithing Shop at Lackland was trying to work "on the cheap" recycling as much of already-in-hand M4s s they could.

The other concern is the particular geometry of the seatpan kit's internal volume--for all we know a FoldAR might be too deep; I have no idea where to find dimensions on the kit or a reference sample to work from, and I doubt the boys in blue would respond with anything less than sending their private Gestapo at OSI for a rather unfriendly chat.

Certainly an idea worth exploring someday...

[Stickman]

I like the way it turned out. Very outside the box thinking.

[Diamondback]

I like the way it turned out. Very outside the box thinking.

Thanks, Stick--this project was my gunsmith's last hurrah before they close up shop and flee this blighted Communist zombie-apocalypse hell for Idaho.