300 Blackout questions

[Bashby]

I’m thinking about putting together an AR pistol in 300 blackout. Been researching for a while and it seems more questions come up with every one answered. I want a short barrel, probably 7-8” range. I plan to suppress it, though I haven’t chosen a can yet. I will be casting boolits for it, haven’t chosen a mold yet.
I have read that some have trouble with cast boolits in a short barrel getting action to cycle. Is this something I should worry about?
Boolits will be PCed. What molds have people had the most success with?

[Hanzy4200]

I only have experience with the 230 gr Lee offering, but I have never had any issues. I run a 10.5" barreled upper with a Silencerco Hybrid 46 suppressor. With some really light loads I hade some hiccups but as long as you are not trying to use lightweight pills like 150's you should be fine. I'm using mostly CFE BLK.

If I had to do it again, I would probably skip the Lee and get something from Accurate Molds. He has some really nice options. The Lee just isn't the most accurate bullet.

[shell70634]

I shoot the Lee 230 gr boat tail intended for tumble lube pc'd over Shooters World Blackout out of a 9.5 inch pistol length and suppressor. I think around 1050 fps. Runs the gun fine with acceptable accuracy, 2-4 inch. NOE 235 grain better accuracy but feeding is hit or miss.

[Bashby]

I see barrels with 1:7 or 1:8 twist rate. 1:7 is preferred for cast, right?

[BK7saum]

1 in 7 is preferred for long heavy bullets, especially streamlined jacketed 240-250 grain bullets. Either the 1 in 7 or 1 in 8 should handle any cast bullet you would put though it.

[Burnt Fingers]

I see barrels with 1:7 or 1:8 twist rate. 1:7 is preferred for cast, right?

1:10 would be better.

I've had NOTHING but trouble trying to shoot cast out of a 7.5" 300 Blackout.

I went to the range today with some gas checked boolits and had OK luck. I could get 3 or 4 bullets out of 5 to kind of group. In some cases there was no idea where the other 1-2 boolits went.

The load I was using would not reliably cycle my AR. I might have to switch buffers in it.

I've tried dozens of loads, boolits from 125 gr up to 235 gr, and not one cast boolit would group till the limited success today.

I've got everything on order to build a 10.5" 300 Blackout upper. Maybe that will work better for me.

Also, even with the gas checked boolits today I was getting lead deposits in the muzzle device and on the bolt.

[popper]

10" 1:8 pistol gas no can, most everything works. 170 gr RD @ 900 fps is fun.

[sutherpride59]

USE GAS CHECKS OR PC WITH A CAN, if you don’t it’s lead city in there. Screw what others say I’ve never had a baffle strike from gas checks. I’ve had good luck with the 311299 from NOE but it’s only 200 grn. If I got another it would be the NOE 240 grn. If you want a good suppressor guy that stands by his product I have a guy who is running a small shop, customer service based, and a pleasure to chat with in general. He asked I never post about him because he likes to stay small and doesn’t want a lot of press but joe is the man. I’m having him replace a baffle after I made a stupid and he isn’t even charging me. Heavy is the way to go for sure though. Play around with a big heavy mold(not the lee) and see what you get. H110 has been minute of pig for me but I’ll be switching back to CFE BLK probably due to position sensitivity issues. Please PM me and I’ll give you my number, I can give you good data in a 5-10 minute conversation of what I’ve done and run into. I’d love to hear what you find after you start loading. Also my barrel is a 8.5” ballistic advantage 1 in 7.

[osteodoc08]

PC a plain base NOE mold. Use CFE BLK or 1680 and you’ll do fine.

I’ve also found using Lancer 300 BLK specific mags to solve my feeding issues.

[sukivel]

I PC and use the Lee 155 gr and Noe 232 gr with IMR-4227 and both cycle perfect everytime.


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[Drew P]

It’s easy enough to get them to cycle, what’s hard is getting them to cycle AND remain sub sonic. THAT is the trick and requires a few special powders and some diligent testing. Those are h110 and 1680. Until I got those two I struggled to get functional subs.

[Conditor22]

A 1:8 twist rate will give you more options for lighter bullets/boolits.

AR pistol shoots 250 grn nicely

[Bashby]

A 1:8 twist rate will give you more options for lighter bullets/boolits.

AR pistol shoots 250 grn nicely

I was thinking that if I were trying to stay subsonic heavier boolits would be preferred.

[mto7464]

The Lee PC'ed put lead in my can. Maybe a flat base or gas check would be best. I just shoot j's in my can now. Too much money to lead it up.
I have Miha's heavy BO boolit. Good boolit but can only use hiteck on it to get it to chamber. I got the lube grobe flat base. If I would do it over I would ge the gas checked version.