Best AR caliber for cast boolits

[farmbif]

Ive been toying with idea of putting a different caliber barrel on an AR. right now its a 300BO. I've been reading about the 14 and 15 twist rate barrels Wilson makes chambered in 300 HAMR was thinking its might be real good as cast bullet shooter. but I'm no expert.
what are your experience and opinions on an ideal cast bullet caliber and twist rate barrel for an AR.

[imashooter2]

I have no problems with a 1:8 twist 16 inch 300 BLK AR. I only shoot supersonic and use the Lee C312-155-2R. The very heavy boolits the sub sonic guys shoot can require a faster twist to stabilize at the low speeds.

[Rapier]

I would consider a 358 cartridge in the AR-15 platform. Several versions to pick from with very good hunting stats for cast.

[WinchesterM1]

I shoot lead in all my ARs other then the 6.5 grendel. If I were you a 9mm AR is fun and cheap to shoot and brass can be picked up by the buckets. I stopped picking up 9mm brass years ago after I got my 5th 5 gallon bucket of it. My 50 Beowulf shoots the Lee 501-440 good, the 450 does OK out to 100yards the 300 blackout (7.5” 1/8) is really hit or miss, it took me 7 NOE miles to find one that would chamber decent enough to be reliable. I don’t know how the people on here load the Lee 311-155…. That just doesn’t happen in my 300s (3 of them) with out being so short it’s almost scary, my 223 shoots okay with the 1/9 but I just build a light weight (5.8lbs with leupold 1-5x20 scope) in a 1/12 and I haven’t had the chance to play with it yet. My 7.62x39 AR shoots good with the NOE 310-130
I haven’t had any problems with the gas tube on any of the ARs clean up is just normal cleaning. Just make sure the nose fits in the chamber that is a big problem I have with my PCed bullets

[MarkP]

What others have said

350 Legend
12.7 x 42 mm (50 Beowulf)


No personal experience but I would expect the 458's for the AR platform would ideal candidates for cast.

[Fitz]

in the AR-15 the 300 HAM'R , 277 wolverine, and the 358 yeti do real well .In the AR-10 the 358 win., 375 Raptor and the 45 Raptor and all the mentioned have been proven on good sized hoggs
The 300 HAM'R likes a 180 gr. bullet
the 277 Wolverine does well with a 140gr. and a 125 gr.
The 358 Yeti a 200 gr.
The 358 win. a 250 gr.
The 375 Raptor seams to like what ever I feed it which so far has been a 325 gr., 345 gr. and a 375 gr.
And the 45 Raptor is the least accurate but with a 405 gr. will do 1 in. at 50yds and about 2 1/2 at 100 yds but for a hog stopper they don't run.
'

[johnly]

I've had good results shooting the 311410 in my AR pushed by just enough 2400 for operation and haven't tried cast in my 450 SOCOM.
The RCBS 180 gr. 35 caliber silhouette sized to .356" is my go to bullet for my 350 legend.

[Baltimoreed]

The .45acp is always a good caliber for lead. I built this one. Check out Macon Armory’s cool .45 ARs.

[fastdadio]

Southern Michigan hunting rules answered the question for me. 350 Legend. Two deer down with the 18" AR so far. I am not disappointed.

[Texas by God]

My 1-7" 16" .300BO doesn't like cast so far. No matter - it's at its best with 110gr VMax for my purposes. I'm going to try the 230gr Lee in it for plinking grins and see how it does.
I was talked out of the 7.62x39 AR that I put together by a pig hunting buddy. It had a 16" 1-10" .308" barrel and it shot the few cast bullets that I tried into small groups. Based on that, I would start there before going to the extra expense associated with the wildcats or specialty AR rounds- just my opinion.

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[popper]

I use cast in 308 ar and 300 BO, 1:10 or 1:8. All supers but some slower @ 1400. Hamr barrel is for short bullets, that may restrict what you can use. Bigger heavy lead just means more alloy is needed. Elk, moose and bear may need bigger stuff but not hogs or deer. I have no need to try 223 in cast. But the choice is yours.

[gundoctor]

A powder coated 230 Lee @ 1350f/s works well in my 16" 1 in 7 twist 300 Blackout Ar using Accurate 1680. 100 yd groups run 1.5".
I'm going to try Hodgen LIL gun next. I've been told that LiL gun's max load can be as high as 1700f/s.

[Photog]

Hand-loading for 300BLK for the AR is the whole reason the cartridge exists. While I personally don't see the benefit of having it in my handloading repertoire, there are some really good things about it:
1. you can load 110gr to 230gr .309 cast pills and make them either super or sub. Lee .309 moulds make good enough plinkers. Just make sure you have a way to regulate gas, and get a pistol length gas system in your upper.
2. 223 brass is plentiful and cheap, it takes very little effort to convert it to 300blk
3. Slowish pistol powder and fast rifle powder can be made to work. Lots of leeway in powder, and its hard to over-pressure an ar with so little case capacity. (Just don't go filling it to the brim with Titegroup) I even use less than-a-casefull (8-15gr) of W296 and get great velocity and complete burn. W296 is always on sale somewhere.

300BLK can duplicate .38 Long or 7.62x39 and all in between. I think it does best when its on the light bullet/slower speed side, think 150gr at 1300fps, or 110gr at 1500 fps (in cast). With 147gr jacketed, it works great at 2000fps. 1:8 to 1:10 seem to be preferred, my 1:8 Saturn 5R barrel is what i am basing my opinions upon.