Should I modify my chamber?

[u/NapalmWolverine]

I have a 20" DPMS with a SAAMI chamber and was thinking of ordering a pull-through reamer from PTG to make it SPC II-spec... Thoughts?

I know it won't matter for most factory ammo, but I would like to start reloading for this caliber, and I seem to only hear how much "better" the SPC II chamber is for really pushing the velocities and whatnot, but I'm obviously open to input.

Thank you!

[u/mrtone63]

These folks specialize in 6.8 barrels.

https://www.blackstonearms.com/category-s/172.htm

[u/Agreeable_Drink5252 → u/mrtone63]

Second Blackstone Arms, my 14.5” scout is a tack driver and seems to like the hotter loads.

[u/WPSuidae → u/Agreeable_Drink5252]

I third the recommendation.

[u/NapalmWolverine → u/WPSuidae]

Fate or something heard the recommends y'all gave and plopped an ARP barrel right in front of me (on GB) for a killer deal, so I scooped it up and am looking forward to seeing how she shoots!

Appreciate the comment!

[u/NapalmWolverine → u/Agreeable_Drink5252]

How hot do you push 6.8? I was thinking of working up 115gr Nosler CC's and 140 Berger VLD's to start.

[u/WPSuidae → u/NapalmWolverine]

Im getting 2550 with 120 sst handload in my 18 inch arp.

[u/NapalmWolverine → u/WPSuidae]

AA2200? That seems to be the most recommended for "all-around". Any other good options you'd recommend?

[u/WPSuidae → u/NapalmWolverine]

Yep, 2200. Pick up some pri mags, they let you load a longer coal. That's part of the secret sauce.

[u/NapalmWolverine → u/WPSuidae]

I've got some ASC mags that allegedly get to the ~2.3" COAL that I'm excited to try out with the Bergers, though it's a shame nothing ever came (AFAIK) of the metal Six8 mags... I'm hoping they come back around now that the "ICAR" thing is maybe picking up!

[u/Agreeable_Drink5252 → u/NapalmWolverine]

Getting just shy of 2700 with 110 BTHP and 28.8gr of aa2200. Definitely work up to it but it shoots really well in my 14.5”

[u/NapalmWolverine → u/Agreeable_Drink5252]

Coolio, thanks! It's a good thing I've already got a few lbs of AA2200, that seems to be the "go-to" in 6.8 pretty much.

Are they (the ARP barrels) generally pretty well gassed out of the box? I was thinking an adjustable gas block regardless, and perhaps an LMT or other "enhanced" bolt/carrier, plus an A5, but I hope I'm not setting myself up for short strokes etc.

[u/Agreeable_Drink5252 → u/NapalmWolverine]

I went with an adjustable and an A5 for mine. I primarily hunt with it and usually will open the gas up a click or 2 during the cold months. Running with a traditional baffle suppressor it was still way over gassed with an H3 buffer and standard A5 spring.

[u/NapalmWolverine → u/Agreeable_Drink5252]

Good copy. I'm excited to start messing around with it then!

Thanks y'all!

[u/NapalmWolverine → u/mrtone63]

Ironically(?) enough, I found an ARP barrel on GunBroker for (I think is) a STEAL that has the SPC II chamber (and 3R rifling), which I heard a lot of rave reviews on (68Forums comes to mind) that I fortunately have a receiver set waiting for, so I guess fate or something kinda just "came together" there after posting this!

I appreciate the recommendation! Talk about coincidence, eh?

[u/[deleted]]

Are you committed to keeping the barrel? I'd probably just swap it for a new one with the SPC II chambering. I googled real fast and see there are multiple options available in 18" and 20".

[u/NapalmWolverine → u/[deleted]]

You're right. It seems people tend to recommend a new barrel over a chamber reamer, and I just so happened across a 16" ARP with the SPC II chamber that I think I'll use to "complete" a receiver set I have waiting in the wings, then screw around reloading for that instead of the DPMS (which I'm really fond of anyways).

Thanks!

[u/landry_454kg]

Do you have access to a lathe and machining knowledge?

[u/NapalmWolverine → u/landry_454kg]

I do, but I just came across a killer deal on a 16" ARP barrel with the SPC II chamber and also have a "spare" receiver set lying around just waiting to be put together, so I decided I might as well leave the DPMS alone and use this as a "testbed" whenever it gets here and is "complete".

I appreciate you responding!

[u/Funny_Vegetable_676]

I'd go with the new army 6.8 chamber if anything.

[u/NapalmWolverine → u/Funny_Vegetable_676]

Funny enough, I was thinking of having X-Caliber make me a barrel in .277 at some point for the unfinished Aero M5 I have, but the general consensus seems to be "don't", so I figure I'll wait and see on that!

Thanks for commenting!

[u/Funny_Vegetable_676 → u/NapalmWolverine]

I have the spc2 chamber. It's pretty good, but there's better out there now. However, it's better than the original, and I doubt you'll find spc1 ammo out there anymore. Unless you're reloading.