SPR Inspired Build

[Vegas]

https://i.imgur.com/bQyg2ml.jpg

I have been wanting to do an SPR style build for a while and a Knights stripped lower seemed like a good place to start. I was trying to do the build on a budget so a full SPR clone was out. Figured I would at least go with an A2 stock, pistol grip and standard trigger guard. I took my time picking stuff up in sales. The upper was one of those Arms Unlimited $30 camo Colt uppers finished with BCM parts. A while back AU were doing $50 Colt LPK's with no trigger and I had a spare QMS kicking around so I'm using that till I switch it out with a G2S. The A2 flash hider has already been replaced with an ASR mount to allow for suppressor use. My aim is to shoot mainly 75/77gr and attempt to stay at MOA from 100-600. We shall see! Full parts list:

Lower
Knights Stripped Lower
Colt LPK with ALG QMS trigger
White Oak Armament A2 stock

Upper
Colt stripper upper with BCM parts
White Oak Armament SPR barrel, rifle gas, 1/7
White Oak Armament BCG
Radian Raptor LT Ambi CH
Silencerco ASR flash hider
Knights URX4 13" MLOK rail
Magpul bipod mount, Harris bipod
Vortex HSLR 4-16x MOA FFP
ADM Recon Mount

This is the 5th AR I have built but the first time I installed a set screw gas block. WOA were great to deal with and dimple the barrel for you prior to shipping. I went back and forth on what barrel to get but these seem pretty well regarded and when they went on sale for $195 during Black Friday it was a no brainer. Was also the first time installing parts in a stripped upper but it was pretty straight forward. Work is busy this time of year but I managed to sneak an hour over the weekend to zero and shoot a couple of groups. I recently picked up some (cheap pulled) 77gr SMK's and had some ready to go with 23gr Varget and Rem #7-1/2 primers, loaded to 2.26 COAL. First few groups were around 1.25" and this one below was the best and last of the day. With the two stage installed and the barrel settling in over the next couple of hundred rounds, I'm pretty confident the groups will shrink a bit. Overall, I'm very happy with the build so far and look forward to pushing it to 600 and beyond.

https://i.imgur.com/vD0njvo.jpg

Thanks for looking.

Cheers.

[Renegade04]

Looks good. Nice compilation of parts. I built something similar a few years ago. It is more of a REECE type build. I do have a Mk12 Mod 0 clone as well.

https://i.imgur.com/Jq0qYjN.jpg

Upper Receiver:

New Frontier Armory Billet Upper Receiver
Compass Lake Engineering Recon 16.1" Douglas Stainless (polished) 1:8 twist barrel w/ mid-length gas system and .223 Wylde chamber
Compass Lake Engineering Stainless Low Profile Gas Block (.750)
Compass Lake Engineering Stainless Mid-length Gas Tube and Roll Pin
WMD NiB-X M16 Bolt Carrier (polished) w/ Compass Lake Engineering Match bolt
Advanced Armament Corp. Non-Mount Blackout Flash Hider
BCM Gunfighter MOD 4 charging handle
Midwest Industries SSM M-LOK Series One Piece Free Float Handguard, 15-inch Rifle (MI-SSM-15) (black)
MAGPUL M-LOK Rail Panels (Stealth Grey and Black)
MAGPUL MBUS Gen 2 Front & Rear Flip-up Sights (black)
Harris Bipod BRM
MAGPUL M-LOK Bipod Mount
VORTEX VIPER PST 1-4x24 TMCQ MOA scope (w/ tactical turrets)
VORTEX/American Defense RECON-X 30mm QD mount

Lower Receiver:
C3 Defense Billet Lower Receiver
GEISSELE Super Semi-Automatic (SSA) trigger
KNS Precision Gen.2 Mod.2 Non-Rotation pins
MAGPUL MOE Pistol Grip
MAGPUL B.A.D Lever - Battery Assist Device
MAGPUL Trigger Guard (black)
MAGPUL CTR Stock - Mil-Spec (black)
BCM Stock Mounting Kit (Mil-Spec) w/ "H" buffer

[Vegas]

Very nice Renegade. A Compass Lake Douglas was one of the barrels I considered. How does it shoot?

[Renegade04]

Very nice Renegade. A Compass Lake Douglas was one of the barrels I considered. How does it shoot?

Shoots extremely well. The first time out, I was getting about .5MOA@100 yards with M193. I have yet to go past that distance as the range is only 100 yards. They will be expanding to 300 yards at some point. There is another range about 35 minutes from me that is 200 yards. There is another that is 1000 yards about an hour away, but I have yet to go there since it requires becoming a member or having a member with you.

[nksmfamjp]

Pretty impressive builds....

I’ll share mine....
20” mid weight WOA 1:8 223 Wylde bbl
Superlative has block
Miculek comp
Brownells MPI/HPT BCG headspace checked
Geissle HiSpeed setup as match
Spikes upper/lower
Magpul PRS
ERGO Tactical Deluxe Grip
ALG V1 rail

Really like the way the parts came together.

With my XM193 duplicator reloads, it was 1.5-2.0” at 100 yds during break in....I could have cried!
Put some thrown together Hdy 75 reloads
and shot 0.9”@100 yds.....I guess I need to get serious about my loading! So, looking at Starline or Hornady Brass next to get it going.

[Vegas]

^^^ Very nice.

I load with CBC brass that had from a case of 62gr a couple of years ago. With my 16" BCM SS410 barrel, I had good luck with Hornady 75gr and 69gr SMK's that was 1/8. 1/2 - 3/4 MOA was typical. I usually load Varget but have some XBR on hand to try also. I plan on picking up some H322 as well to give markm's load a try.

[nightchief]

Great build! I wish I would have built my Precision AR with this barrel instead of the LaRue Stealth barrel. Look forward to hearing how it shoots at 600 yards!

[Renegade04]

Great build! I wish I would have built my Precision AR with this barrel instead of the LaRue Stealth barrel. Look forward to hearing how it shoots at 600 yards!

I did a build a couple years ago with an 18" LaRue Tactical Stealth barrel that I won. At 100 yards, I have managed to put three rounds touching each other using M193 ammo.

https://i.imgur.com/oL8dlXS.jpg

[swallisa]

@Vegas good choice on WOA barrel have the same in 1/8


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[Vegas]

Great build! I wish I would have built my Precision AR with this barrel instead of the LaRue Stealth barrel. Look forward to hearing how it shoots at 600 yards!


@Vegas good choice on WOA barrel have the same in 1/8

Thanks Gents. Once I get a load dialed in after the holidays, will see what it can do. The range I go to has target frame holders every 100 out to 500 yards so will be able to see how it groups at distance easily.

[nightchief]

I did a build a couple years ago with an 18" LaRue Tactical Stealth barrel that I won. At 100 yards, I have managed to put three rounds touching each other using M193 ammo.

Best I have done at 100 yds is a 1 1/8" group using Hornady 75gr OTM factory loads. GECO 55gr was around 2". Never tried M193 with it. Some of this is undoubtedly the skill of the shooter and I always shoot off a bipod or a range bag, so perhaps not the most stable rests to really find out the barrel's best accuracy.

[Vegas]

I usually shoot off a bipod and small rear bag, either at a bench or prone. I handload 99% of the time but ironically one of the best groups from my 16" BCM SS410 was 69gr Gold Medal Match at just a hair over .9" at 200 yards. With standard 55gr ammo, I'm lucky to shoot 1.25" at 100 yards with a 5 round group.

[Vegas]

Couple of 300 yard groups from today. Not too bad for using the QMS. In the bottom group, got that nice flyer there which I believe was the last shot of the magazine. I read somewhere recently that last round with the bolt locking back can cause flyers because of the change in pressure/harmonics of the bolt not returning to battery. I never really considered that before but seems feasible. Can anyone confirm or debunk that theory?

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

https://i.imgur.com/dQzmLj2.jpg

[crosseyedshooter]

I read somewhere recently that last round with the bolt locking back can cause flyers because of the change in pressure/harmonics of the bolt not returning to battery. I never really considered that before but seems feasible. Can anyone confirm or debunk that theory?

Those seem like respectable groups. After building 16” and 14.5” middies, I feel like an 18” SPR-type build is in my future.

As for bolt lock back, I’ve seen graphs with dwell times around or under 200 microseconds, which is the time that the bullet has passed the gas port but hasn’t left the muzzle. The gas starts acting on the bolt in this time interval. For the sake of theorizing, a cyclic rate of 800 rpm translates to 75 milliseconds, or 75,000 microseconds per complete bolt cycle. Basically, the bullet is long gone before the bolt ever gets to the locked back position. That’s my thinking, anyway.

[Vegas]

If I can keep that going to 600, I'll be happy. I think there is room for improvement with the load and once I switch in a 2 stage, I'll probably see a small incremental improvement.

Thanks for the insight on the bolt movement. Assuming those numbers are correct, probably no impact to accuracy. The other variable I didn't include was these groups were shot suppressed.

[Vegas]

So switched from Varget to XBR to see how that works with the 77gr SMK. After a couple weeks of messing around, found a decent load that seems to work with a light crimp and 2750 -2790fps. The top are crimped with a Rem bench rest primer, the bottom two are no crimp with a cheapo Sellier & Bellot primer. The results with the S&B primer were pretty consistent at just over MOA. The Rem primer is consistently sub MOA.

Bottom line, the barrel is shooter for sure with the right combo.

https://i.imgur.com/9O7IeEM.jpg

https://i.imgur.com/bMpe2fB.jpg