New AR Build Caliber

[603Country]

From the OP’s list, since he already has a Grendel, which is similar to the 6.8 SPC, I think the 300 HAM’R would be the one I’d choose. Being a hunter more than a target shooter, that would fit my needs better for pigs. With my preferred choices, back when I wanted more pig knockdown power than the 223, I went with the Grendel, but that was driven mostly by the fact that I had everything I needed to load for it, except brass, which I found plenty of. If not for that, I might have gone with the 6.8 SPC.

Probably the big factor in the OP’s decision is what’s he gonna do with the new caliber - long distance targets or short range hogs.

 

[taylorce1]

Probably the big factor in the OP’s decision is what’s he gonna do with the new caliber - long distance targets or short range hogs.

I know deer will be on the menu, I don't know how bad hogs have invaded North Carolina. I'm a .300 Blackout guy over the Hamr, but that's because I love shooting suppressed. I've shot a deer with a 7.5" pistol and 125 grain supersonic load, and it worked well. However I have no doubts the 6 ARC and 6.8 SPC would work better than a .30 cal based on a .221 or .223 case.

 

[USAF Ret]

I know deer will be on the menu, I don't know how bad hogs have invaded Nort Carolina. I'm a .300 Blackout guy over the Hamr, but that's because I love shooting suppressed. I've shot a deer with a 7.5" pistol and 125 grain supersonic load, and it worked well. However I have no doubts the 6 ARC and 6.8 SPC would work better than a .30 cal based on a .221 or .223 case.

No hogs here in NC. Deer and coyotes are mostly the menu. Hogs, maybe one of these days.

 

[USAF Ret]

Well, three polls on different sites and the answer is overwhelming.

6mm ARC it is. Got my armorers kit and the lower parts ordered. Time to shop and get to work.

 

[stagpanther]

Good luck finding brass.

 

[stagpanther]

I made my ARC brass from grendel brass, pretty straightforward--but this is a challenging one to bite on for your first build. If you can find one--get a super-bolt and then get a depth gauge so you can accurately measure your fired brass to get an idea of what your shoulder set-back needs to be. That's the key, find the sweet spot that allows just enough expansion to seal but doesn't overwork the brass. the only other thing to watch out for might be where that neck thickness goes when you neck down, (I think a slight COL trim before sizing down is necessary), it can possibly result in a donut forming at the base of the neck. i've done wildcats from both grendel and 6.8spc brass--the 6.8spc being the tougher, better design overall IMO. Other than that--the only remaining challenge is keeping your grendel brass sorted from the ARC brass that you crafted.

 

[taylorce1]

I'd just buy loaded ammunition if no brass is available. Like I pointed out innanother post, it isn't ideal but it'll get it you started. 100 rounds of loaded ammunition will get a person started, and honestly a 6 ARC isn't going to be a high volume shooter. Just get a brass catcher so you don't have to chase down that hard to find brass.

 

[USAF Ret]

I made my ARC brass from grendel brass, pretty straightforward--but this is a challenging one to bite on for your first build. If you can find one--get a super-bolt and then get a depth gauge so you can accurately measure your fired brass to get an idea of what your shoulder set-back needs to be. That's the key, find the sweet spot that allows just enough expansion to seal but doesn't overwork the brass. the only other thing to watch out for might be where that neck thickness goes when you neck down, (I think a slight COL trim before sizing down is necessary), it can possibly result in a donut forming at the base of the neck. i've done wildcats from both grendel and 6.8spc brass--the 6.8spc being the tougher, better design overall IMO. Other than that--the only remaining challenge is keeping your grendel brass sorted from the ARC brass that you crafted.

I will do just like I did with my Grendel. Get Hornady ammo. Shoot to break rifle in and reuse brass. Plus, I can reform the Grendel brass if needed.

I do have a brass catcher. Thank you sir.

 

[USAF Ret]

I made my ARC brass from grendel brass, pretty straightforward--but this is a challenging one to bite on for your first build. If you can find one--get a super-bolt and then get a depth gauge so you can accurately measure your fired brass to get an idea of what your shoulder set-back needs to be. That's the key, find the sweet spot that allows just enough expansion to seal but doesn't overwork the brass. the only other thing to watch out for might be where that neck thickness goes when you neck down, (I think a slight COL trim before sizing down is necessary), it can possibly result in a donut forming at the base of the neck. i've done wildcats from both grendel and 6.8spc brass--the 6.8spc being the tougher, better design overall IMO. Other than that--the only remaining challenge is keeping your grendel brass sorted from the ARC brass that you crafted.

Thank you sir.

 

[stagpanther]

Good plan. BTW--I'm just another "netschmuck"--you do not need to call me sir as I do not believe I warrant that respect, "Stag" will do.

 

[USAF Ret]

Retired military and southern. Muscle memory. Haha.

 

[jetinteriorguy]

Not to muddy the waters, but have you looked the .277 Wolverine?

 

[603Country]

On buying loaded ammo for the new caliber, that doesn’t always work out. I way overpaid for Hornady 6.5 Grendel ammo, but justified it by intending to reload the brass 4 or 5 times or more. When shooting the reloads the first time, the brass split and even shattered. Out of the 50 rounds I reloaded, 49 were not usable again. The Starline replacement brass is reloading fine.

 

[taylorce1]

Out of the 50 rounds I reloaded, 49 were not usable again.

I wouldn't have shot 49 out of 50 rounds to figure that out. If I had a couple cases rupture, I would have torn down the cartridges and started over. You need to go buy lottery tickets.

 

[USAF Ret]

The deal is done. Just ordered a 6mm ARC 20" Ballistics Advantage barrel. I was weighing going with the 22", but this is a hunting rifle, so went with the 20. They have a sale going on, so it was a pretty good deal.

Thanks for the help Shadow9mm.

 

[Shadow9mm]

The deal is done. Just ordered a 6mm ARC 20" Ballistics Advantage barrel. I was weighing going with the 22", but this is a hunting rifle, so went with the 20. They have a sale going on, so it was a pretty good deal.

Thanks for the help Shadow9mm.

No problem, happy to help.

 

[USAF Ret]

Well, I pretty much have everything on order except the gas block and tube. Went Aero Precision with all hard components - lower receiver, upper receiver, hand guard and buffer tube and spring. Went with a B5 Bravo stock as it is more flared for a good cheek weld and has a soft rubber butt pad (I always end up replacing the Magpul buttpad with a Limbsaver).

Waiting on a Shadow9mm to give me a report on the Aero Precision adjustable low profile gas block.

 

[Shadow9mm]

Well, I pretty much have everything on order except the gas block and tube. Went Aero Precision with all hard components - lower receiver, upper receiver, hand guard and buffer tube and spring. Went with a B5 Bravo stock as it is more flared for a good cheek weld and has a soft rubber butt pad (I always end up replacing the Magpul buttpad with a Limbsaver).

Waiting on a Shadow9mm to give me a report on the Aero Precision adjustable low profile gas block.

Lord willing and the river don't rise, that will be tomorrow. Mighty excited to try an adjustable block.

 

[USAF Ret]

Lord willing and the river don't rise, that will be tomorrow. Mighty excited to try an adjustable block.

I have gotten feedback on another forum that the folks that have the AP adjustable block love it. Looking forward to the report.

 

[USAF Ret]

Large haul of boxes coming in today. I expect interrogation from the Mrs. Haha.