Home Forums Hunting & Shooting AR and Tactical Rifles AR Build

I’ve got an AR15 lower and upper sitting in safe, thinking about building something other than a 5.56. Would mainly be for gun range and the occasional hunting trip when I don’t want to take a bolt gun & there are a plethora of pigs. I’m thinking 6.5 Grendel, 7.62x39, or 6mm arc.

What say the brain trust, what would you build and why? I’m not sold on any of them, arc is probably my least likely just because of lack of ammo and cost of ammo. I’ve had a 300 blackout, don’t see myself doing that again. Thanks

300 Hammer, 5.56 bolt, 308 barrel, 30-30 ballistics. Easy to make.

350 legend, and for [bleep] and giggles make her a piston gun too

Do you reload? If so, the .300 Ham'r is a hoot, and it does a number on pigs.

I built my .300 Ham'r with a Wilson barrel. The Ham'r is cheap to reload with Speer 130 HPs or 125gr TNTs. Both of those bullets are regularly $18-22 a box. There are usually a lot of inexpensive factory seconds available in the 110-130gr range, as well. Just get Starline brass, though, and save yourself the trouble of making your own from .223 brass. I tried making my own, and I wasn't impressed with the results - lots of cracked necks.

If you don't reload, .350 Legend ammo is pretty cheap and should also do well on pigs. It took a little polishing and tweaking to get my BCA upper to feed reliably, but I'm happy with it now.

Both the .300 Ham'r and .350 Legend use the standard .223 BCG, which I like. The Ham'r likes .300 Blackout mags, and my favorites are the 10-rounders from Lancer. I'm running designated CMMG mags for the .350 Legend, and they are less than $20, as well.

I've never owned a 7.62x39, Grendel, or ARC, so I can't comment on any of those.

300 Ham'r for close-up hunting, 6mm ARC for longer range shooting, and the 7.62x39 for cheap blasting. Take your pick.

That's exactly why I chose the 7.62x40 (before the Ham'r became available).


I've been using range-scrounged Remington brass to make cases just because I have a lot of it. I've formed hundreds with zero cracked necks. One thing I do is trim to initial length before forming it. It's very easy brass to form and I often just let it lay after firing.

The grendel works awesome on deer sized game, have taken 1/2 dozen with it including a buck that went 180#. the arc has taken a few groundhogs but shoots incredible, have hit steel and rocks to 1100 yards.

Hadn’t considered the Ham’r but will definitely have to do a little research on it. I like that I can use 5.56 bolt as I’ve got an extra lying around. I do reload, not a fan of making my own brass so would definitely go star line for that.

Appreciate the input, keep the feedback coming. Thanks

Consider me a fan of the .300 Ham'r, also. I'm a big fan of the .30-30, so it was natural to me to try the Ham'r. I ended up converting one of the 6.8s I have.

It has been very easy to get it to shoot accurately. I have two barrels, an 18" and a 20". I am in the minority in that I prefer the 20" and the rifle set up as a rifle w/o collapsing stock and using the rifle tube/buffer, makes a very soft shooting rifle.

Edited to add: This rifle DOES have the collapsible stock and carbine buffer.

I have mainly shot various 150 grain loads, but really like the Speer 130 and 135 bullets, too. I didn't try too hard, but 170s seemed to be a little much for the smallish case. CFE BLK is my preferred powder.

I've used the .30-30 to shoot a lot of deer, and some bear and pig, too, so the Ham'r is like an old friend in more modern clothes.

Having a 6.8 SPC led me to not trying the 6.5 Grendel, but if I were to do it today, availability of components would make the 6.5 my choice.

No experience with the ARC.

Interesting. Do you anneal the necks before sizing?

I used R-P .223 brass, as well. I cut them down, sized, and then used my power trimmer to get them to the exact length and chamfer/deburr (RCBS 3-way cutter). Out of the 50 case I made, about 10 of them had cracked necks and were unusable.

I'll second what Vic said - CFE-BLK powder works so well in my .300 Ham'r, I haven't played with anything else.

Link to .300 Ham'r Loading Data

He's not wrong.

I gotta admit, you got me on this one. My process sounds exactly like yours. I do not anneal. When I make the initial trim, the case neck is entirely removed & I'm well into the shoulder (1.560"). Then I hit them with Lyman spray lube and run them into the sizing/form die. Then clean up with a deburr.

I guess your initial trim would be to 1.564"?

Perhaps the 1 mm (~.04") extra length of the Ham'r makes a difference? I would never guess that, as deep into the shoulder as the 7.62x40 gets.

So far three good choices. I have a 300 HAM'R 18" with a 1/15 SHAW Barrel. I am in the middle of a 6.5 Grendel Build. My Compass Lake 20" Barrel "Douglas Blank" is on order, waiting it's turn. I am also seriously considering a rebuild on a 204 Ruger AR to a 6 ARC. If I start this build it will probably be a 20" Compass lake on a Douglas Blank.
All of the above have Rifle Gas as well as Rifle Buffer's. I have a couple MagPul MOE Stocks so far. I will probably convert my A2 Stocks to MOE sooner or later.
The 300 HAM'R shooting 130 Speer bullets is economical. Shooting Steel Hangers at the Range you do not need to wonder if it is a 223. You can tell a real difference in the impact.

Bob R