What to replace the 6.8 SPC II with

[Mike6158]

I built a couple of AR's over Christmas. I finished a 6.8 SPC II, 1:7 twist, that I bought the parts for a few years ago and built a 300 Blackout from scratch. While I was at it I started down the path of building an 8.6 Blackout.

The 300 Blackout shoots great. The 8.6 needs a barrel. The 6.8 SPC II needs bullets that currently don't exist right now (factory had a fire). I had planned for the 6.8 to shoot subsonic but that's starting to look like I made a bad choice. I have no problems with swapping the barrel out but I'm a bolt action guy. What's a good caliber that works well, subsonic and suppressed, on hogs?

You may be thinking, so just shoot the 6.8 SPC II with standard loads. I sighted the 6.8 in today with 115gr HP BT (Rifle Line ammunition. I'd never heard of them but I figured they would go bang and they did). At 100 yards, no suppressor, the 4 shot group is 2 minutes ish. Attach the suppressor (Sandman L) and they are spread out around 12 minutes or more apart. That's right... 12 minutes at 100. I moved to 50 and the groups without the can were even better. With the can they were in a long vertical string that was spaced 6-8" apart. The top hit was 6" below the point of aim and the other three were lower and to the left. The last one was about 2' low and 1' left. No baffle strikes that I can see. The can shoots great on the 300 Blackout and .223 that I forgot to mention in the first paragraph.

200 gr or heavier 6.8 SPC bullets are not available. I can't find them if they are. So... I'm looking for an alternative. Plan B is to take the Key-Mo off, put the muzzle brake back on, and shoot it "loud". The 1:7 barrel will be swapped. I'll keep it to try again when the factory starts making 200+ grain 6.58 SPC pills.

 

[Coyote Shadow Tracker]

We have a good friend that wanted to build an AR and debated between a 6.8 SPC II and 300BO. This was back in Nov 2021. He got a good deal on a PSA upper.
I more of less talked him into the 6.8 SPC II.
He bought several boxes of factory ammo I think around the lower 100 gr. I offer to help him reload and all he would need are the dies since we have everything else. Ammo was very hard to find at this time.
When he got it, we shot behind our house on our range. He was wanting results FAST and only cleaned with a bore snake against what I proposed for a cleaning break- in method. I shot 3/4" MOA right off the bat. then he wanted to keep shooting. Told him the barrel would heat up since it is a small diameter and not broke in. Well he kept shooting and the groups kept getting larger. He was under the assumption from reading on the internet that he knew all about the 6.8 SPC II and it should be shooting in the same hole.
He left our house very disappointed and think that he might have got rid of the AR shortly afterward.
He bought several boxes of factory ammo I think around the lower 100 gr. I offer to help him reload and all he would need are the dies since we have everything else.
With everyone's opinions out there what would be the ideal load for the 6.8 SPCII? It is a 1:7 with a 20" barrel. Basically, shooting Yotes and Hogs. Also thoughts on the PSA uppers.
I was thinking that if he still has it and doesn't like it that I would buy it. He is the type of a person that changes firearms, boats, vehicles real fast if he has any issues.
Thanks
Len & Jill

 

[Mike6158]

I reload (20+ years of it) so making a subsonic or supersonic round is easy. I bought a barrel that was specifically designed to shoot a heavy bullet subsonic. 1:7 twist and the bullet is 200 grain. BUT the heavy bullets are really hard to come by. Woodleigh was making them for Bison (barrel supplier) and they had a fire that ended the heavy bullet supply. I have dies, brass, primers, powder... no bullets.

 

[Coyote Shadow Tracker]

I reload (20+ years of it) so making a subsonic or supersonic round is easy. I bought a barrel that was specifically designed to shoot a heavy bullet subsonic. 1:7 twist and the bullet is 200 grain. BUT the heavy bullets are really hard to come by. Woodleigh was making them for Bison (barrel supplier) and they had a fire that ended the heavy bullet supply. I have dies, brass, primers, powder... no bullets.

I can't remember but what is the difference between the 6.8 SPC and SPC II if any ?
So what is best for a faster load for Yotes or does the 6.8 SPC group shoot heavies for subsonic?

 

[Mike6158]

There's some minor difference in the shoulder if I remember right. Apparently the bullets don't care as they fire form to the chamber. Idk to be honest. It's just what I've read.

The heavy bullet is for subsonic. The .308 shoots great subsonic with 200 - 230 gr bullets. The 1:7 twist was specifically purchased to stabilize a 200 gr bullet at subsonic velocities.

I can easily stick with 6.8 SPC II and just put earplugs in

I've got a little CZ in .22LR that drives tacks at 50 yards. Suppressed it's dead quiet. I'm thinking about trying it out on coyotes. I'll have to my my thermal over and sight it in though. It's easier just to leave the .223 / thermal together and use that suppressed.

 

[P7M13]

I have a Bison SPC barrel - great shooter. Have you tried 180's instead? I predominantly shoot Speer 130 HPs in mine.

I can't remember but what is the difference between the 6.8 SPC and SPC II if any ?
So what is best for a faster load for Yotes or does the 6.8 SPC group shoot heavies for subsonic?

From memory, the original that Remington built was 1:10 and a tight chamber with short throat. It would jam up after a couple mags.
They loosened the chamber, lengthened the throat (~4 mil - or a few hundred rounds of wear) and changed the twist to 1:11.
My Bison barrel is an original SPC and 1:10. I've not remeasured the chamber, but suspect it's worn itself to SPC II specs.

 

[Mike6158]

No but I'll bet 180's would work better than the light bullets I have (Barnes TTSX). I just checked the cabinet and I have 180gr Berger VLD's for 7mm but not 6.8 SPC

 

[ARlife4me]

The spc2 was a headspacing (safety) improvement, throated differently and a slightly higher pressure. Subs aren't really a spc thing, unless you're using a really short barrel and need to feed from a mag (ar style 2.260"). I'm not sure how heavy 1 could go and still get enough bearing surface on the neck?

 

[ARlife4me]

I have a Bison SPC barrel - great shooter. Have you tried 180's instead? I predominantly shoot Speer 130 HPs in mine.


From memory, the original that Remington built was 1:10 and a tight chamber with short throat. It would jam up after a couple mags.
They loosened the chamber, lengthened the throat (~4 mil - or a few hundred rounds of wear) and changed the twist to 1:11.
My Bison barrel is an original SPC and 1:10. I've not remeasured the chamber, but suspect it's worn itself to SPC II specs.

Might want to check and see if you're using a spc2 bolt!

 

[Mike6158]

The BCG in mine is SPC II
Bison was selling 200 grain 6.8mm bullets until the factory had a fire. The 1:7 and 200 gr bullets, as I understand it, were intentional.

That said, subs are slowly slipping off the list. I've got some good subsonic shooters.

 

[P7M13]

Might want to check and see if you're using a spc2 bolt!

I doubt it is SPC II. I've never checked or cared -- have just shot it since buying it. And, except for the original ten boxes of Nosler 110gr bullets I bought for it, I've only shot my reloads -- well over 1K at this point.

My 2nd 6.8 does have a SPC II barrel and SPC II bolt.

Edit to add: The original Nosler ammo had pure lead tipped SP bullets that would deform when they hit the load ramp and sometimes not feed properly.

 

[BALLISTICJESUS]

Are you using a muzzle device to attach your suppressor to? Or are you going direct thread?

I have a 6.8 SPC 12.5" that I run a Silencer Co Omega 300 suppressor on. If I use the quick attach/detach muzzle brake that came with the suppressor along with the quick attach/detach rear assembly on the suppressor the rifles shoots poorly. It took me some time to figure it out. My barrel is threaded 5/8-24. So I removed the Silencer co muzzle device and quick attach/detach rear plate. Installed the 5/-24 rear direct attach plate and threaded it straight onto my barrel. Snugged it up. The rifle was shooting 3" or so with the quick connect set up. With the same load after I went direct attach my groups tightened up to this @ 100 yards.

3 shot group bellow.

 

[jake545]

I can't remember but what is the difference between the 6.8 SPC and SPC II if any ?
So what is best for a faster load for Yotes or does the 6.8 SPC group shoot heavies for subsonic?

Mainly freebore and correcting the angle of the lands etc that were transposed in the beginning and not caught until saami approval. There was almost a 90 degree angle where the lands started and caused pressure spikes in early testing. Someone transposed numbers in the reamer print and didn't catch it. The spc ii is how it should have been in the beginning but they did lengthen the freebore a little. The bolts are the same but some may be marked as spc ii but there is zero difference. The head spacing is the same as well. It's very similar to how the 556 and 223 are, other than the mess up on the lands. Pretty much all factory loads now says are down loaded to be same in the original (messsd up) chambers.

 

[Coyote Shadow Tracker]

Well
we want one and has a friend that has on. only problem he does not reload no more but with his Daddy was and ol Timer reloader and GS the OLD School. IM am sorry he passed before he could pass on some to me.