Just a couple of quick notes on the Bison Armory 6.8 SPC subsonic platform (AKA 6.8 BSP).
1. A 16″ Bison 1:7 twist barrel with carbine length gas will cycle 180 and 200 grain subsonic ammunition WITHOUT a silencer. This includes bolt lockback on the last round in the magazine.
2. All Bison 1:7 twist barrels will handle all commercially available 6.8 SPC ammunition, including SSA Tactical loads.
3. Field testing has shown no difference in accuracy between the 1:11 twist 16″ recon and 1:7 twist 16″ recon. Reports from customers have indicated that the 140 Sierra Game King performs extremely well when loaded supersonic in the 1:7 twist barrel, especially for ranges beyond 200 yards.
4. Shooting subsonic with or without a silencer is fun. Without a silencer we still recommend hearing protection, but simple ear plugs will do, recoil is minimal, blast is diminished substantially, all of which makes it a great back yard plinker, especially for the kids. The only draw back is the ammunition cost of the subsonic rounds.
Here’s another Bison Armory 16″ BSP carbine. It’s a demo that we loaned to some fine folks at the 68 forums for a member shoot. The carbine is sporting a new 11″ Troy Alpha rail with flip front sight. Pretty slick.
Our delightfully crappy West Coast spring weather cleared up long enough for us to make it to the range and really put in some quality time testing our new 7.62 NATO / .308 Winchester barrels. The results were outstanding, and we easily achieved sub-MOA results at both 105 and 219 yards. Why these weird distances? No idea. But whoever set up the range obviously wanted to make it just a wee bit more difficult than usual.
At 105 yards, Ben put together the winning group using Federal Gold Medal Match .308 ammunition tipped with 175 grain SMK bullets and measured 0.84″ (measuring the greatest distance between the centers of any two shots in the group).
The 105 yard group
Ben working on a nice 105 yard group
At 219 yards, James nailed down the best group using Silver State Armory 7.62×51 ammunition tipped with 168 grain Sierra OTM bullets and measured 1.84″
The 219 yard group
James dialing it in at 219 yards (Not even our camera knew what to do about all the sun in the background)
Here’s the rub: Twist rate makes ZERO difference to barrel performance. My earlier theoretical analysis appears to be supported and I expect that twist rates equal to or slower than 1:4 will see no appreciable difference in pressure or muzzle velocity. So far I haven’t seen any difference with 16″ 4-groove barrels in 1:7 vs 1:11 twist.
The numbers (mv in average of several shots):
16″ 6.8 BSP”
SSA 115 OTM: 2492 fps
SSA 110 TSX: 2547 fps
SSA 85 TSX TL: 3010 fps
16″ 6.8 SPC II 1:11″
SSA 115 OTM: 2493 fps
SSA 110 TSX: 2575 fps
I had exactly 5 rounds of the 85 TSX TL and didn’t have any left for the SPC II 1:11″ twist. I’ll get those next time. I didn’t measure accuracy closely but I was shooting about 1.25″ to 1.5″ at 105 yards with everything. Neither barrel showed better accuracy than the other. The brass looked exactly the same. With a suppressor or without, didn’t make any difference.
More testing will follow with the SSA Tactical loads
We put our new 18″ SPR 7.26mm/.308 Winchester rifle through its paces at the range this week. This rifle features our .308 Winchester compatible 7.62mm NATO chambered barrel. The overall performance was flawless. The Chrony was set up 15 feet from the muzzle, and we loaded up with Hornady 155 gr A-Max and Winchester 168 gr Ballistic Silvertip ammo. The A-Max achieved a muzzle velocity of 2685 fps, and the Silvertips hit 2365 fps. Reliability was perfect. At the end of the session we had a nice pile of .308 brass sitting at 3:30 about 10 feet away. Our MA-TEN based BR-X rifles were designed to go bang every time the trigger is pulled, because we know your hunting trip or your life may depend on it.
The first session showed good accuracy with 1.5 MOA 5-shot groups. Took the rifle out for a second range session because we knew it could do better. The first trip out we found that the trigger was terrible. It was a basic GI single stage trigger, but something was obviously wrong with the mating surfaces between the hammer and the sear. This time out we put a Timney single stage trigger in the rifle with a 4.5 lb pull. What a difference. Here’s our setup:
18" BR-X on the bench
And the view down range:
BR-X on the bench, downrange view
Targets are 105 yards from the muzzle. No Chrony on the second day as it was raining and miserable. This time we brought several different types of ammo including 150 gr Hornady SST Superformance, and hand loaded 150 gr SMK and 150 gr Barnes TSX
The Bank
And the results
Range results
Starting at top left: the first group was fired with 150 gr Sierra Match King over 46 grains of H4895. The first shot is for sight in, then moved a few clicks left and called it good for testing. As you can see, there are many three shot groups that would be great, but three shot groups are for sissies, so I manned up and shot 5 in each group. This is more a testament to my shooting still than to the rifle. Our professional shooter Dave wasn’t available for this range day so I had to do the dirty work myself. First group came in at 1.36″, measuring the groups as the largest distance between the centers of any two shots in the group. This produced a respectable 1.34 MOA.
The second group at the top right is 150 gr Barnes TSX over 46 grains H4895. Woof! I didn’t even bother measuring that one. From the left at the bottom: 150 SMK over 43 gr Varget, 150 Hornady SST Superformance, 150 Barnes TSX over 43 gr Varget. The rifle obviously likes the SMK’s, and with some time put into load development, should be able to push MOA or better. This will be our focus in the future. I’m also looking forward to the weather warming up and a nice sunny day at the range. Once I get a good load dialed in, it will be time to call Dave to put up some real groups.
Silencers really make shooting fun. We brought a lightweight 16″ carbine to the range for some fun with an Ops-Inc 12th model silencer.
BR-15 carbine, Ops-Inc 12th Model silencer
Silencers are expensive, the wait for the paperwork to go through is a drag, but they’re worth the trouble. Once you shoot suppressed, you’ll never go back. And you’ll never move to California.
We do offer expedited shipping but you have to call/email for a shipping upgrade. We will upgrade your shipping to UPS 2-Day or UPS Overnight for the actual cost.
This has been a point of confusion, both for us at Bison Armory and for our customers. Here’s how we use the available order status terms:
1. Awaiting Fulfillment: This is the default order status when you place a new order. This status indicates that we haven’t done anything yet with the order.
2. Pending: This order status indicates that we have entered your order in the system and are either waiting for parts that are not in stock, waiting for FFL confirmation for lowers and rifles, or are getting your order together and building any assemblies included in your order.
3. Refunded: A status of “Refunded” indicates is the same as pending except that we have applied any partial refunds that you have coming (e.g. for free shipping, LEO/Military discount, or order changes and errors).
4. Shipped: Touchdown! Your order is on it’s way to you. Your UPS/USPS tracking number is available on your account/order page and you should be receiving emails from both Bison Armory and UPS Quantum view with your tracking number.
