AR 15 6.8 SPC built and review

Glock357 · Mar 3, 2014

Completed rifle: review and range report

Hi all,
its been a while since my last post. It took a while to get the upper back from Bison Armory. Because of the hunting season and Christmas they shipped the rifle early February. Since then I shot it 3 times, once at the NRA range right after attending the Chantilly gun show, and the past 2 weekends at the Carol County shooting range.

After some hand lapping with Fritz polishing compound and the JB cleaning paste and me getting used to shooting further than 50 yards after more than 15 years without a rifle I managed to get 1 inch groups at 100 yards and 2 inch groups at 200 yards. I tried the cheapest ammo I could get online, Hornady 110 gr v-max, Sellier and Bellot 110 gr FMJ, and Federal Gold Dot 90 gr soft top and they are all consistent and accurate.

Here are some pics of the rifle and I will give a more detailed review below:

wailer · Mar 3, 2014

Glock357 said:
Hi all,
its been a while since my last post. It took a while to get the upper back from Bison Armory. Because of the hunting season and Christmas they shipped the rifle early February. Since then I shot it 3 times, once at the NRA range right after attending the Chantilly gun show, and the past 2 weekends at the Carol County shooting range.

After some hand lapping with Fritz polishing compound and the JB cleaning paste and me getting used to shooting further than 50 yards after more than 15 years without a rifle I managed to get 1 inch groups at 100 yards and 2 inch groups at 200 yards. I tried the cheapest ammo I could get online, Hornady 110 gr v-max, Sellier and Bellot 110 gr FMJ, and Federal Gold Dot 90 gr soft top and they are all consistent and accurate.

Here are some pics of the rifle and I will give a more detailed review below:

Your finish product is a beauty, just finished my 6.8 build as well great work.

jimbobborg · Mar 3, 2014

Go here http://shop.ssarmory.com/ammunition/6-8mm.html order the 110gr soft points, which are loaded with Sierra Game King bullets. Save the brass and reload. The ammo you purchased is original SAAMI spec ammo, which is not as fast as the newer Spec II ammo. Plus the SSA brass has more volume.

MikeTF · Mar 3, 2014

Glock357 said:
Hi all,
its been a while since my last post. It took a while to get the upper back from Bison Armory. Because of the hunting season and Christmas they shipped the rifle early February. Since then I shot it 3 times, once at the NRA range right after attending the Chantilly gun show, and the past 2 weekends at the Carol County shooting range.

After some hand lapping with Fritz polishing compound and the JB cleaning paste and me getting used to shooting further than 50 yards after more than 15 years without a rifle I managed to get 1 inch groups at 100 yards and 2 inch groups at 200 yards. I tried the cheapest ammo I could get online, Hornady 110 gr v-max, Sellier and Bellot 110 gr FMJ, and Federal Gold Dot 90 gr soft top and they are all consistent and accurate.

Here are some pics of the rifle and I will give a more detailed review below:

Is that a 45 degree angled red dot that I see? What brand? What mount?

I like the rifle. I have a 6.8, but I've been too busy to mount optics and was considering an aimpoint straight up on the rail for short range, and then using a LaRue quick disconnect mount with a leopold scope for longer range shooting.

Hog hunting is the intended purpose of the rifle, and possibly home defense (hence the aimpoint).

jimbobborg · Mar 3, 2014

MikeTF said:
Is that a 45 degree angled red dot that I see? What brand? What mount?

I like the rifle. I have a 6.8, but I've been too busy to mount optics and was considering an aimpoint straight up on the rail for short range, and then using a LaRue quick disconnect mount with a leopold scope for longer range shooting.

Hog hunting is the intended purpose of the rifle, and possibly home defense (hence the aimpoint).

That looks like the Bushnell mini-dot.

MikeTF · Mar 3, 2014

jimbobborg said:
That looks like the Bushnell mini-dot.

Thanks. If I did an angle mount it would be with an Aimpoint® Micro T-1.

jimbobborg · Mar 3, 2014

MikeTF said:
Thanks. If I did an angle mount it would be with an Aimpoint® Micro T-1.

I have the same Bushnell, which is going back on my Win 94. The battery life isn't bad, not Aimpoint good but I'm using the same battery that came with it, which is 2 years old now. It has handled 200 rounds of various .45 Colt loads.

MikeTF · Mar 3, 2014

jimbobborg said:
I have the same Bushnell, which is going back on my Win 94. The battery life isn't bad, not Aimpoint good but I'm using the same battery that came with it, which is 2 years old now. It has handled 200 rounds of various .45 Colt loads.

I'll admit that I'm tempted by the Bushnell, the aimpoints are pricey and I've read that the Bushnells are high quality.

Glock357 · Mar 3, 2014

Go here http://shop.ssarmory.com/ammunition/6-8mm.html order the 110gr soft points, which are loaded with Sierra Game King bullets. Save the brass and reload. The ammo you purchased is original SAAMI spec ammo, which is not as fast as the newer Spec II ammo. Plus the SSA brass has more volume.

Thanks,
I didn't have a chronograph but based on the moa drop between 100 and 200 Hornady gave me about 2550 muzzle velocity and S and B a bit faster. I will try the SSA ammo as well. I am collecting brass to start reloading. Never done it before so there is a few pieces of equipment I need to get first. I was wondering why factory ammo was so much slower compared to some of the handloads published.

Glock357 · Mar 3, 2014

wailer said:
Your finish product is a beauty, just finished my 6.8 build as well great work.

thanks, I was worried not going with the standard caliber on the AR and I am glad to see how many others have 6.8s. At the Chantilly show a few weeks ago there was plenty ammo and a few mag options.

Glock357 · Mar 3, 2014

Is that a 45 degree angled red dot that I see? What brand? What mount?

I like the rifle. I have a 6.8, but I've been too busy to mount optics and was considering an aimpoint straight up on the rail for short range, and then using a LaRue quick disconnect mount with a leopold scope for longer range shooting.

Hog hunting is the intended purpose of the rifle, and possibly home defense (hence the aimpoint).

Regarding the red dot, it is a Bushnell mini dot. Its an ok sight for the purpose I need it, less than 25 yard shots in case I get surprised by a deer when I still hunt on windy days. I am watching my budget for the whole built so I only pay for higher quality when its essential. Regarding battery life, when I first got this scope I forgot it on for 2 weeks and it still runs.

What do you get for about $80 shipped is a fairly small dot, about 1-2 moa, but it is not quite a symmetric circle (the only reason I noticed its not symmetric is that I looked through it with my binoculars at x6 to match the dot with the Nikon crosshair at 60 yards which saved a lot of ammo zeroing it in) and the lens is pretty dark, so it wont be really good for low light situations. Also sighting it is a bit of a pain, especially when its mounted at 45o.
The 45 degree offset mount is a Daniel defense (originally designed for the aimpoint, it is very high quality and very expensive and come in a nice box).

if you have the money and you really need the high quality features go for the aimpoint. If you can live with some of the lower quality features (dark glass and a pain to zero), but still need a sturdy, reliable red dot that is faster than iron sights this one is not too bad.

Glock357 · Mar 3, 2014

bangbangbye said:
interested to see how you like that buffer spring.

So after 3 shooting sessions so far I like the spring and buffer system (JP silent captured spring). It cycles the gun as expected and so far I tried 90 and 110 grain bullets. The recoil is effectively non existent. When shooting at a 100 yards the muzzle moves less than 5 moa. this is with a target crown. I have never shot another AR before or the standard spring so I cant compare.

MikeTF · Mar 3, 2014

Glock357 this is a great write up and thank you for answering so many questions!

Glock357 · Mar 3, 2014

Bison armory 6.8 spc upper

Since I described the lower in great detail earlier I will only write about the upper here:

Upper: Bison 6.8 Remington SPC 20 inch fluted with target crown

Barrel/Finish: 20 inch heavy fluted (under the forearm) with rifle length gas system. Bead Blasted for a mat finish
Upper Receiver: Bison Armory Forged
Forearm: YHM Lightweight Rifle
Forearm rail covers from Magpul
Standard 6.8 bolt
Bolt Carrier: Young Mfg Phosphate
Gas Block: Bison Armory Low Pro
Charging Handle: Standard
Hunting scope (Nikon Prostaff 3-9 x 50 mm) and a Burris, PEPR scope mount. Sighted in at 200 yards for Hornady 110 gr V-max
Backup sight/ short range / fast acquisition: Bushnell micro dot on a Daniel Defense 45o offset picatinny mount.
Sling: Blackhawk universal sling with quick detach picatinny mount on the forearm
Bipod: UTG tactical/sniper adjustable with picatinny mount.

The final rifle is 40 inch long and it weighs 11 lb.

I am sure people are curious, this setup cost me a total $2150 including shipping and the transfer costs. I also probably spent another $200 on tools I didn't have and cleaning supplies. Also I figure so far I spent about $80 every time at the range. I ll start saving money for reloading tools as I figured each round will cost me between $0.50 to $0.75 instead of more than $1 I pay now for ammo, and hopefully it will match the premium ammo quality which is almost $2 per round.

Glock357 · Mar 3, 2014

Barrel

This was not a match grade barrel so it needed lapping and brake-in. After visually inspecting the bore the button rifling marks were quite pronounced and after the first time at the range there was quite a bit of copper fouling. The first time shooting it at 50 yard for sighting in I was surprised at the half inch groups I got, but my shooting session 8 days ago was a disaster. I couldn't get smaller than 3 inch groups at 100 yards or 6 inch at 200. It was partly me getting used to the scope and setup but as it turns out the barrel needed lapping badly.

I got a tube of flitz polish to start and JB bore paste to finish and used a cleaning rod and patches to get a decent polish. This made quite a difference as I was able to get less than 1 inch groups at 100 yards and my best at 200 yard was 1.5 inch but the average was 2-2.5 inch. Moral of the story, lapping make a difference. It also made cleaning the bore a piece of cake.

The barrel looks great, but its heavy. The bead blasting helps to get rid of the stainless steel shine. The 11 degree crown looks perfect and the bead blasting ends at about 1 mil from the bore.

The weight of the barrel is balanced by the weight of the stock and I can balance the rifle on 2 fingers under the magazine.

Overboost44 · Mar 3, 2014

I have been waiting for your latest installment. Thank you. On my build, I will follow much of your advice and some from the other few 6.8 builders on here. I have a few questions... 1) Would you change anything if money was not important?
2) You have a nice fluted barrel, but you can't see the fluting. Did you do it for cooling and weight only?
3) I was going with the same stock. Do you consider it the right choice?
4) How much does the complete rifle weigh? As it sits is fine unless you have it w/o the tripod and optics.
5) I guess you don't know if you would have been happier with a billet upper?

ETA: your last post helped, but I didn't see it before posting.

Glock357 · Mar 3, 2014

Upper receiver

The upper receiver is the standard Bison armory forged aluminum. Ideally a billet upper would probably better match the billet lower, but I was trying to keep the costs down.

The two gripes I have with the upper are the over sized holes for the take down and pivot pins result in a significant rattling when mated to the lower, and the m4 feeding ramps do not match 100% with the barrel extension. I have not had any feeding issues so neither issue probably matters for the rifle's functionality.

To address the issue of rattling I did 2 things:

I installed an O-ring around the pivot pin post on the upper as many people suggested online.
I bedded the take down pin area in silicon to prevent rattling but to allow flex when needed.

The idea for silicon bedding came from 2 places: people usually bed their barrels of bolt action rifles and there is a commercial product called accuwedge that can sit behind the takedown pin in the lower receiver. I didn't want to get the accuwedge since many people weren't happy with it so here is what I did:

I prepared some smoothon silicon and used plasteline to make a dam sealing the trigger group area and the buffer tube area. I then I leveled the lower, poured the silicone and closed the rifle up in the level position. after 6 hours I removed the custom silicone wedge very easily since silicone doesn't stick to anything, I tempered it for 30 min at 160 F and voila. This silicone is designed for making chocolate molds and is stable up to 400F. This solved the rattling.

Other than that the tolerances of the upper with the bolt currier charging handle and other components are as expected.

jimbobborg · Mar 3, 2014

Ben used to use YHM upper receivers, I don't know if he still does or not. When I got my upper from him, I did a break in procedure. IIRC when I hit the 100 round mark the accuracy was markedly improved. I ordered a barrel like your without the fluting, but I got shipped a threaded barrel. I put a PWS FSC-30 on it, which actually helped out when I'm trying to call my own shots.

Glock357 · Mar 3, 2014

Overboost44 said:
I have been waiting for your latest installment. Thank you. On my build, I will follow much of your advice and some from the other few 6.8 builders on here. I have a few questions... 1) Would you change anything if money was not important?
2) You have a nice fluted barrel, but you can't see the fluting. Did you do it for cooling and weight only?
3) I was going with the same stock. Do you consider it the right choice?
4) How much does the complete rifle weigh? As it sits is fine unless you have it w/o the tripod and optics.
5) I guess you don't know if you would have been happier with a billet upper?

ETA: your last post helped, but I didn't see it before posting.

Thanks for the vote of confidence.
If money wasn't an issue I would have gotten a 308 bull pup with a 30 inch barrel

.
Seriously I would have gotten a matched lower and upper so that the pivot and takedown pin holes would be the same size. I don't know if that is an option anymore.

I would pay more for a match grade barrel as accuracy and precision would be guaranteed. I would buy a higher mag scope with better turrets and better adjustment wheels. I would also buy a nickel coated bolt and carrier and sturdier charging handle.

To answer your questions: I love the stock, the barrel came fluted like that, I wanted a 20 inch heavy profile for weight balancing and precision. The fluting under the forearm helps minimally with weight and some for cooling. I suppose if it was fluted all the way to the crown it would look cooler.

The rifle is 11 lb complete, its a bit heavy for an AR15 based rifle, but the barrel and stock are the main culprits and wouldn't change either.

I don't know if a billet upper would have tighter pin holes. I think its important to get a matched pair. I actually like the forged more than the billet receivers. Other than the oversized holes the upper forged mates with the lower billet perfectly.

Glock357 · Mar 3, 2014

jimbobborg said:
Ben used to use YHM upper receivers, I don't know if he still does or not. When I got my upper from him, I did a break in procedure. IIRC when I hit the 100 round mark the accuracy was markedly improved. I ordered a barrel like your without the fluting, but I got shipped a threaded barrel. I put a PWS FSC-30 on it, which actually helped out when I'm trying to call my own shots.

According to their website the receivers are made by mega. I couldn't do the shoot and clean brake in procedure as my time at the range is always limited, so I chose to polish the barrel instead. I am sure when I shoot a bit more it will improve.

AR 15 6.8 SPC built and review

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