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>

[Texas by God]

Yes old eyes typo. That "309250" would be a loong bullet lol.

[brstevns]

Thanks for the load information, I have a 30x223 in a bolt action and have been looking for some loads.

[Bad Ass Wallace]

Thanks for the load information, I have a 30x223 in a bolt action and have been looking for some loads.

Is that the same as the 30 Apache? I would love to build a cast boolit rifle with 1:10" twist barrel, 24 or 26" in length and throated to suit the Lyman 311284. Problem is that most rifles with small bolt face have magazines that are simply to short to feed.

[brstevns]

Is that the same as the 30 Apache? I would love to build a cast boolit rifle with 1:10" twist barrel, 24 or 26" in length and throated to suit the Lyman 311284. Problem is that most rifles with small bolt face have magazines that are simply to short to feed.Yes it is, traded for a 18 inch barrel that has a 10 1/2 twist that is fitted to a Savage action. I have tried a few loads using Win 680 with a 110 gr hornady bullet and the Lee 230 gr .309 bullet. The heavy lee seems to be showing promise, but has about a 3 and 1/2 foot drop out at 200 yards, if sighted in for 100.
Have not tried the 311284 bullet,

[blueeyephil]

I have been, but will not in the future as I have a can now. Actually, I've been light jacketed and Leatherhead 220's lately. I planned on using the Lee's for a cheap plinking round. As usual, I'm not getting in near as much shooting as I'd like.