most accurate 300 blackout subsonic mold for ar15

[ok300blk]

I have a lee 309-230-5r mold in route from midway. Have any of you had good results with the accurate 31-240a or 31-215e in an ar15? Any accuracy reports on these molds?

These will be shot out of my aac 16" upper for now. (An sbr is in the works). They will also be shot with a suppressor once I am 100% sure they are stable.

Are there any other molds I should consider for this application. Also I will powder coat

[45r]

I'm very happy with the groups I get with my Noe 311365 PC boolits.
The mold drops PB boolits at 202 grains without any sticking.
Under an inch all the time at 55 yards using 11.1 grains RE-7 with fed primers seated to 2.110 in my AAC 16 inch.
Burns clean and quiet.

[ok300blk]

Have you had any feeding issues?

[Elkins45]

I have the NOE 311365 plain base and it has been a good performer for me as well. So has the Lyman MXL 195 grain tapered. I'm still trying several others but those two seem to be the top contenders. The 311365 is super pointy and feeds like a jacketed bullet.

I have also had success with the Lee 230, but I can't get the NOE 247 to shoot well at all in my suppressed SBR.

[wordsmith]

After a learning curve, I was able to get the subsonic NOE 247 PB to shoot very accurately (1.0-1.5" @ 100 yards) in both 300 BLK (10.5" and 16"), as well as 308 (16"). Here are the details:

Mix: 50/50 COWW / SOWW + 2-3% Tin (11-12 BHN)
Lube: Hi-Tek Gold (2x coats)
Size: 0.310 (modified Lee sizer)
Die: Lee with oversized sizing stem (0.309) for 0.001-0.002 neck tension
Crimp: Lee FCD just enough to remove bell from Lee Universal Neck Expander

Despite posts to the contrary, this bullet fully stabilized in my 1:10 308 barrel. The JBM stability factor was about 1.9 at sub velocities, which proved out in real life. Just FYI for those that are convinced it can't be done.

[runfiverun]

I have shot the LEE boolit super slow in my 1-7 twist rifle but it's a bolt action so the 3.5gr load wouldn't even begin to move your BCG.
it would for sure be quiet with a can [it's quiet without one]

the lyman 311359 [@125grs] has turned out to be a good one in the wife's ruger on top of 9.5grs of AA#9
it might be worth taking a look at for your AR if the throat is just a tick on the large side of .310, the spire point nose lends itself to good feeding.
my AAC rifle dotes on the rcbs 165 gr silhouette boolit on top of that same 9.5 gr load.
it may not feed well in your rifle though.

[Elkins45]

After a learning curve, I was able to get the subsonic NOE 247 PB to shoot very accurately (1.0-1.5" @ 100 yards) in both 300 BLK (10.5" and 16"), as well as 308 (16"). Here are the details:

Mix: 50/50 COWW / SOWW + 2-3% Tin (11-12 BHN)
Lube: Hi-Tek Gold (2x coats)
Size: 0.310 (modified Lee sizer)
Die: Lee with oversized sizing stem (0.309) for 0.001-0.002 neck tension
Crimp: Lee FCD just enough to remove bell from Lee Universal Neck Expander

Despite posts to the contrary, this bullet fully stabilized in my 1:10 308 barrel. The JBM stability factor was about 1.9 at sub velocities, which proved out in real life. Just FYI for those that are convinced it can't be done.

I can't get them to group well at all from a 1:7 Blackout. From a 1:10 308 at subsonic speeds I had several go thru the paper sideways at 50 yards. I'm afraid to shoot them thru my silencer on 308 for fear of baffle strikes.

Do you mind sharing the powders you are using to get good results?

[wordsmith]

I couldn't get them to shoot well from 1:8 and 1:7 twists at first either. That was my learning curve. What I found was that I had to get the BHN just right (about 11-12), which balances the forces induced from the fast twist with the softness needed to obturate the boolit base properly. I started about 9 BHN to try and get something that would expand, and couldn't get them to group well. I steadily increased the BHN to 12 and upped my size to 0.310 and everything is working very well now. Obviously if you're getting keyholing, something is not right and don't screw on your suppressor. I will tell you, however, that I've tested them in 2 different 1:10 308's and they both worked great. YMMV.

For the 308, the only powder option (IMHO) is Trailboss. Very good results, 20 shot SD's of 8.8 fps (Magnetospeed) and very accurate. One trick with 308 is to seat to almost the end of the driving bands to get 2.800". Really helped stabilize the bullet in 308.

For 300 BLK, there are several powders which folks have used successfully, but I use AA 1680 almost exclusively since it will cycle AR actions and works well in bolts also. KISS principle. You can use fast pistol powders as well, which are a little quieter, but I found them to have higher SD's and lower accuracy.

One last thing, and no insult intended if you understand this already, but proper neck tension is critical with cast boolits. I'm telling you because it took awhile for this to sink in to my thick skull coming from j-word reloading. I ordered custom oversized sizing stems from Lee so I can get 0.001 - 0.002" of neck tension, and no more. If it's too tight, it'll squeeze the driving bands too much and undersize the driving bands, wrecking accuracy. Once I put all this together, they shoot lights out.

[pls1911]

Wordsmith, would bet you're not getting much in the way of obturation at the velocities and pressures encountered with your subsonic loads. Your move to .310 improved your bullet to barrel fit from the gitgo. My guess is that's the basis for your improvement.
I run all my .30 cal through a .312 sizer if the chamber will take it,,,,otherwise I always use a .310. With the exception of an old SAECO #316, .the .312 only lubes and seats the gas check.
Also, all my slugs are heat treated to mid 20s bhn...

[wordsmith]

pls1911 - Very possible that I'm getting minimal obturation, as QL is predicting only 20.9k psi. Recovered boolits show good performance of the boolit base, with full rifling engraving and full diameter, so hopefully I'm getting some. I will agree the bump up to 0.310" made a big difference, but I think getting my neck tension correct, throwing my Lee FCD in the j-word loading box, and using a normal taper crimp die to just remove the belling made the final difference.