Lee 300 Blackout Subsonic

[natchomamma]

Considering purchasing the Lee 300 Blackout mold from Midway (TL309-230-5R) for subsonic 300 blackout. Seems to be a mixed bag of reviews and not sure what else to purchase (i.e. gas check, sizing die, etc...)

Do I need to size them? If so what size Lee sizing die?

Gas checks? If so what size?

Thanks.

[curator]

The Lee TL309-230-5R bullet mold is a good deal for the price. If you are good at casting you may not need to size them after casting. I size mine to .3105 and I cast from WDWW+2%tin alloy which give me BHN 22 after a few days "aging." The bullet is boat-tailed and while you can fit a gas check on the base it may not stay on the bullet once it leaves the barrel. It is a "tumble-lube" design and is engineered for sub-sonic speeds and works best at low pressures (24K or less) My .300 BLackout has a pistol length gas system so it functions well with subsonic loads. Carbine or mid-length gas systems often have issues with functioning shooting subsonic without a suppressor. I am generally happy with my Lee mold (what does one expect for $22 these days?) as I have found various loads where it shoots fairly accurately and is very inexpensive compared to condom-ized bullets.

[natchomamma]

Sounds promising if all I need to do is pour and tumble without having to resize and use gas checks. I've used Lee's TL 9mm and 45ACP molds successfully.

Thanks.

The Lee TL309-230-5R bullet mold is a good deal for the price. If you are good at casting you may not need to size them after casting. I size mine to .3105 and I cast from WDWW+2%tin alloy which give me BHN 22 after a few days "aging." The bullet is boat-tailed and while you can fit a gas check on the base it may not stay on the bullet once it leaves the barrel. It is a "tumble-lube" design and is engineered for sub-sonic speeds and works best at low pressures (24K or less) My .300 BLackout has a pistol length gas system so it functions well with subsonic loads. Carbine or mid-length gas systems often have issues with functioning shooting subsonic without a suppressor. I am generally happy with my Lee mold (what does one expect for $22 these days?) as I have found various loads where it shoots fairly accurately and is very inexpensive compared to condom-ized bullets.

[sdcitizen]

I had to lap the nose section on mine. It was.295 diameter and nothing would make it shoot worth a hill of beans. Got it up to .298, and after powdercoating, it shoots acceptable groups now.

[natchomamma]

Got my mold today and dropped a few. So far these look really nice! I hope they shoot as well as they look. They weigh 231gr. and have a 12.4BHN. Hopefully they will be perfect for subsonic flight!

I wish the mold would drop 6 at a time so I can produce them faster.

[Boolseye]

I have had good success with that boolit, very accurate over 12.5 gr. RL7, cycles a carbine system.
Mine drop around .310, I don't size them, either.

[natchomamma]

I'm having issues with mine. Looks like they are tumbling (see target). I shot these from 15 feet away. Im using a 300 aac blackout upper 16" barrel 1:8

Loading with IMR 4227 10gr. velocity is averaging 1100fps. I'm not sizing them just tumble lube.

Any ideas how to fix? If not this mold is un-usable for me.

[Boolseye]

It looks like the boolits might be getting case-swaged. I would look to your seating stage and be sure the boolits are staying within spec (seat one, then pull it and mic it). Perhaps you'll need to size them to .309 then lube again–I also have a 1:8 16" carbine, and it slugs at .307" Have you slugged your bore? Are you shaving lead when you seat them? That Lee universal expander die can come in handy for that.

[natchomamma]

It looks like the boolits might be getting case-swaged. I would look to your seating stage and be sure the boolits are staying within spec (seat one, then pull it and mic it). Perhaps you'll need to size them to .309 then lube again–I also have a 1:8 16" carbine, and it slugs at .307" Have you slugged your bore? Are you shaving lead when you seat them? That Lee universal expander die can come in handy for that.

I'm just using the Lee Blackout 3 die set. Boolits are dropping at .309 and I'm not sizing them. It does shave the boolits when I seat them. I just pulled one and it shaves it down to .305. Guess this means my boolits are now undersized and this is my problem?

[popper]

Try belling the mouth of dummy case with needle nose pliers to test a few. I use the Lee setup, works for me but your expander may be too small (should be ~ 0.307). Measure OD and wall thickness, expander size. Hard brass may spring back too make ID too small. Your alloy should be OK for subS but possibly too soft to stretch out the neck.

[Boolseye]

That .305" measurement may be the source. Consider a different expander, such as a NOE or lyman that will open things more. You may also want to harden things up, so that the boolits bear on the neck walls more. I use that Lee set too, though have not had that problem–the sizer seems kinda loose in my set.

[natchomamma]

That .305" measurement may be the source. Consider a different expander, such as a NOE or lyman that will open things more. You may also want to harden things up, so that the boolits bear on the neck walls more. I use that Lee set too, though have not had that problem–the sizer seems kinda loose in my set.

Boolseye,

Are you casting yours and using it in stock form (Alox lube)?.... or powdercoating and using gas checks?

What is your setup?

Thanks.

[Boolseye]

I use 45-45-10 (see the tumble lube sticky. This is a much-used recipe hereabouts) for all my tumble-lubing. I don't use gas checks on that boolit–for the speeds I'm shooting them, they're unnecessary. A GC will seat on the base of this boolit, if you care to do it. I flare the case neck, seat them to an oal of 2.170", light taper crimp and done. Have also used 10 grains of 296, but that didn't quite cycle my gun.

FWIW, the boolit is very accurate for me. I think you'll get this without much trouble. it's gotta be fit related.

[dudel]

I have that mold, and it's nice (after breaking in the mold).

I'm using stickon WW and water drop. I lube with LLA, size to .309 (with a Lee push through sizer), then lube with LLA again. No GC. I'm using 4227 (don't recall how many grains). Keeping the boolit subsonic out of an Handi 300BO (1 / 9 IIRC). I Have not chonographed the round yet. I'm pretty sure I'd have problems if I pushed them too fast.

The rifle is dead nutz accurate with Hornady 150gr FMJ-BT. I have not yet found the perfect load for these boolits; but that's half the fun.

[dudel]

I'm having issues with mine. Looks like they are tumbling (see target). I shot these from 15 feet away. Im using a 300 aac blackout upper 16" barrel 1:8

Loading with IMR 4227 10gr. velocity is averaging 1100fps. I'm not sizing them just tumble lube.

Any ideas how to fix? If not this mold is un-usable for me.

That tumbling seems to say that the boolits aren't getting enough spin to stabilize. First thing I would check would be the fit of the boolit to the barrel. Might be worth slugging it.

[runfiverun]

at 305 they for sure aren't spinning.
you only have about .001 contact with the rifling.

work on your cases neck diameter.
I'm using an expander ball from my 7.62x 39 die set and sizing the boolits to 310.
the 310 sizer just touches the bottom drive band.

I'd rather have .001 neck tension, than .001 bore contact.
ohh I also use a version of 45/45 lube.

[MT Chambers]

Bullets are too small for the barrel IMHO, it may work out if you sped them up, alot.

[natchomamma]

After testing this weekend this is my conclusion for my mold....

1.) Needs a gas check
2.) Needs to be powder coated

I was able to get them to work after using a Lee .309 sizer and adding a gas check. After that they were powdercoated with HF red (shake and bake method).

No leading and no more tumbling.

My final thoughts with this mold are if you not willing or able to gas check and powder coat these bullets, don't waste your time. You are taking your chances if you don't.

[gpidaho]

My mould drops small so I too powder coat them. I've run some test with and without gas checks and don't see enough difference to make a difference. I've had my best luck expanding the checks (homemade aluminum) wider than usual and then sizing the boolit through a Lee push through. I'm warming up to this boolit after a somewhat shaky start. Gp

[runfiverun]

the gas check isn't you savior, it's the larger diameter.