Let's Talk 300 Blackout

[308Jeff]

Other than hating to load 223 (except match ammo), I had little/no interest in this caliber. Until I started looking at casting, and now I'm very interested in it.

I've got bunches of correct headstamp 223 brass that I can get converted for $40/1,000 so that part is easy. I know I want to go with a 16" upper at this time (no interest in suppressor), so I have a few questions for you fine folks.

-Can I use Unique powder?
-What twist rate should I be looking at for the barrel (I'm thinking I want to load heavy cast bullets almost exclusively)?
-Which length gas system?
-Can I expect good reliability and accuracy without gas checks (I'll be PC'ing everything I cast)?
-Any recommendations on molds?
-What BNH should I be looking at for my alloy?

[popper]

Unique for bolt guns. So far, 1:10 works for 170gr. normally use a 145gr PB @2100. 1:7 didn't do well at the higher fps.

[jimb16]

Are you looking toward supersonic or sub sonic loads. Makes a difference in recommended twist. I'm shooting up to 180 gr boolits with a 1:8 twist. Haven't had it long enough to have worked up accuracy loads yet, but getting decent accuracy at 50 yards with "thrown together loads".

[SciFiJim]

My wife gave me a gift certificate to build my own for Christmas. I am also thinking 300 blackout, so will be watching this thread with interest.

[blueeyephil]

The 155 gr Lee works well. I think I was getting 1650fps from an 8" barrel. That's off the top of my head. I understand RCBS has a 130gr that might be good for blk. I know you you said you wanted to go heavy but supersonic in this caliber are best lighter. I haven't shot supers heavier than the 155. I used H110.

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[308Jeff]

Thanks for the replies so far.

Let me throw an additional monkey wrench into this by adding that I'd like to shoot the same bullet in my AR-10 as the 300 BLK.

[MT Chambers]

It's a good cartridge for the AR crowd but in a bolt gun it's accuracy is nothing to write home about and it's power is well below the 30/30. Three dif. .30 cals. of mine shoot better and are more flexible.

[308Jeff]

The 155 gr Lee works well. I think I was getting 1650fps from an 8" barrel. That's off the top of my head. I understand RCBS has a 130gr that might be good for blk. I know you you said you wanted to go heavy but supersonic in this caliber are best lighter. I haven't shot supers heavier than the 155. I used H110.

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Thank you! Are you using a gas check with the Lee 155?

[308Jeff]

It's a good cartridge for the AR crowd but in a bolt gun it's accuracy is nothing to write home about and it's power is well below the 30/30. Three dif. .30 cals. of mine shoot better and are more flexible.

Thank you.

[KenH]

One of the first questions to ask, do you plan supersonic or subs? Oops, I see it's already been asked. Unique isn't an especially good powder for 300BO, perhaps better is Little Gun or 4227, and I think some like Reloader 7.

I've got a 300BO with 16" barrel 'n pistol gas system. "IF" you ever plan for subs, then you really do wish to get a pistol gas system so the gas port is at the 4.5" mark on barrel. This keeps the pressure up to cycle system with subs.

A book could be written on different aspects of the 300BO, and just with AR setup of 300BO. Bolt actions are a totally different breed.

Ken H>

[308Jeff]

Thank you, Ken.

I'm probably going to be mostly shooting supersonic.

I asked about Unique because I have more of it on hand than any one person probably should, but I also have a decent amount of Titegroup, AA #9, and Win 296. Wouldn't be hard to get some L'il Gun if I need to.

What's most important to me is a bullet that will feed reliably in an AR and can be shot reliably and accurately without a gas check. I'll be PC'ing, of course.

[popper]

same bullet in my AR-10 as the 300 BLK probably won't work well. I use a 31-165C (GC) for the 308s and 31-142C (PB) for the BO (1:10). Chambers are different. A 31-172C (like a RD nose, Lancer mags only) works good in the 1:8 10" pistol and 30/30. PC for all, close to full jacketed fps. I've got a 150gr PB I used in the 1:7 carbine barrel that also shot well in 308MX. Also have a 4x 31-165A (same as C but with L.G.s) that does fine in 308W. I haven't tried the new BO powder, 110 & 1680 work well for me.

[skeet1]

Jeff308,
I also was not interested in the 300 Blackout until I started thinking about shooting cast in the AR platform and now it is one of my favorite rifles. The Lee 312-155 is a very good bullet choice. I size mine at .311 because that is the sizer I have but .310 would probably be better.

I have recently been trying the Lee 309-230 bullet. There has been a lot of pros and cons about this bullet but so far mine is shooting well and even though I don't have a suppressor I like shooting it sub sonic because the recoil is very light because of the low charge. My rifle is a 8" twist and stabilizes it OK other say it doesn't in their rifles. I think the key is not to size it to small. My mold casts them at .309+" and I just lube with LLA and shoot directly from the mold.

There are a number of powders that work well for the Blackout in the AR, among them are 4227, 296, 4198, Reloader 7, A1680 and Shooters World Blackout. The powder I would be most interested in today would be the new Hodgdon CFE BLK and Powder Valley carries it. I have used 296, 4227, 4198 and I am currently using the "Shooters World / Lovex Blackout" and it works very well. I also tried Acurate No. 9 but it was marginal in my rifle with failure to eject.

One other thing I experienced in my rifle was that the metal GI type magazine failed to feed reliably. I switched to Mag Pul Gen 3, 20 rd. and have not had any further problems.

Ken

[Moonie]

The Unique will absolutely work, but you will then have a bolt action AR... The powders needed are a bit slower, think 1680, RL-7 and similar for the heavies, W296/H110 works well for the middle weights, I've had trouble with W296/H110 cycling our Carbine gas uppers with heavies but the RL-7 does it very well, super or sub. The Lee 312-155 is a great middle weight boolit and the over 200 gr are great for either super or sub, I have a couple that work well and I especially like the NOE 247 or the Accurate 245gr of the same design.

[Texas by God]

My 16" 1-7" likes the Lee 309 150 FP @1800 fps range. Accurate and runs the gun. My gun is carbine gas. Best, Thomas.

[KenH]

What is your OAL when using the C209-150-F bullet? At 1800 fps are you using gas checks? What accuracy are you getting? 1 MOA? 2 MOA? What powder?

I've been using the Ideal 311415,, but it has to be seated fairly deep giving a 1.9xx" OAL so the bullet will chamber. I think my 300BO barrel is almost small in the throat. The Lee C309-230 bullet works nicely with full 2.26" OAL.

Ken H>

[308Jeff]

Thank you, Ken, Moonie, and Thomas!

[brstevns]

My 16" 1-7" likes the Lee 309 150 FP @1800 fps range. Accurate and runs the gun. My gun is carbine gas. Best, Thomas.

Care to share your load ?

[Texas by God]

Care to share your load ?

Sure. Lee C309250F sized/gas checked .309", reformed 5.56 LC brass, 15.5 grs Lil Gun, Win sr primer. I tumble lube very lightly after sizing. Too much Alox makes too much smoke. 3 shots @50 yds average group has been 1-1/4" with my best 3 group 3/4". I fired 50 of these in one day with no stoppages but the gun sure needed a cleaning. I have not tried them on paper at longer ranges but hitting a foot square steel plate offhand is fun practice. OAL is 1-7/8" with no crimp.

[KenH]

" C309250F" That is a typo? Should be C309-150-F? Looking at my loading info it seems my 311415 is getting about the same as your 309-150 is getting getting. I powder coat rather than lube. Lubed for years, but now sorta prefer PC'ing for convenience. I'm loading a bit lighter than you are, I'm around 1400 to 1500 fps with gas checks. Seems like the group opened up a bit when I loaded to 1700 fps, but need to check again.

Ken H>