Poor-arue build:
This all started when one of you assholes posted a pretty killer clearance sale link for Larue barrels. The 16" 308 8 twist Stealth got my interest since I had a new KGM R30T and some other random large frame parts. The wheels got to turning from there.
Info on receiver sets.
So I'd initially planned to build this as a DPMS style using an Aero M5 upper on a JL Billet ambi lower. For some stupid reason JL Billet doesn't make a high profile upper to go with there lower. The short of it is the Aero upper fits like shit on the JL lower. I kind of went down the rabbit whole from there. Ordered a Bkings matched upper/lower set + 1 upper. The B kings set is the best deal hands down for large frame IMO right now.
The BK Mod-0 thermal upper with the ambi lower was $285 on sale. It fits so well I can hold it upside down without pins. I have also verified the Mod- 0 uppers extension bore is .004 undersized for thermal fit depending on barrel extension. That Thermal fit is uncommon for large frames especially at that price point. The extra BK Mod-0 upper does in fact fit the JL Billet lower much better than the Aero. Lines don't match up very well, but fit is excellent.
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In the spirit of this being a Poor-arue build I also ordered an AR10 style Stag receiver set. Decided to go with the Stag set for this.
Build list:
- Stag AR10 receiver set pins included
- Larue Stealth 16" 308 8 twist mid gas made from Atlas shrugged steel
- Hera adjustable gas block with threaded in tube (made in Germany)
- Brownel's low mass carrier
- Rubber city Armory HP bolt & pin
- Battle arms pro ambi selector 45 degree
- Geissele Super charging handle
- Geissele National match trigger
- Wilson Starbust/BCM grip
- Centurion 14" CMR handguard original style
- Magpul enhanced aluminum trigger guard
- Law tactical folder
- Vltor I-mod clubfoot stock & extension
- JP polished carbine buffer spring
- Odin Works adjustable AR10 carbine buffer weight, set to 4.65 oz
- LWRC skirmish BUIS
- KGM R30T
- Vortex PST 2 mil 2-10 in Midwest QD mount
- Larue mags
Upper was loose extension fit like the Aero. The extension was also out of square. Trued the face and used 2 full wraps of ss shim stock on the extension (.004"). Used a trigger shims .005 for front take down pin. Used the stag receiver tension screw set for firm drag on the rear pin. Machined the Stag lower for a PDQ ambi bolt catch as I'd been wanting to try the large frame version. I had to machine the notch in the PDQ .060 wider towards the magwell side.
View attachment 8438771See that little plastic piece next to the screwdriver, I'll get to that in a minute.
Machined .040 off the bottom of the Hera gas block to give more clearance to the spine in the bottom of the CMR handguard. Those Centurion rails are rigid & I like them, but they don't have much clearance for gas blocks.
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I've been using either Dark hour defense or PWS extensions with the extended tail to support the carrier. I've done some rudimentary testing on small frames comparing these to a std extension. When you close the receiver using the extended tail extension I can see the back of the carrier lift as it closes. This does not happen with std extensions. I'm a proponent of squaring the bolts up best as possible. It was bugging me a little that with the Law folder, there is no rear carrier support possible with the above mentioned extensions. This is where that little plastic piece comes into play.
Figured why not. So I machined that from Ultem (high temp, strong, oil resistant plastic). It slides down into the un-used buffer detant hole in the receiver. That little dog point set screw pictured above screws in from the back of the receiver to lock it in. Now my carrier has support with the law folder.
Shown below mocked up with a std extension checking alignment. Does it matter? Hell if I know.
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Got it to the range just to break in and get some brass formed to chamber. Had to make 1 adjustment to gas block closing 1/4 turn.
Ran 4 different loads Noma Tac 150FMJ, Old milsurp Sig 58 Patronen FMJ magnetic, Southern munitions loaded with 155 Hornady HPBT, & of coarse FGMM 168.
The Norma Tac & the FGMM are within 20fps and both shot the best. Norma just over moa & FGMM just under moa.
Then took the FGMM out to 500 x 5 on steel. Very pleased with how it turned out. Cycled all the ammo without a hickup.
Hand loads next.
As a side note: I really like how the Stag receiver lines appear to align with the hand-guard (last picture).
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5 @ 500 FGMM
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