300 Blackout cast load data

[Mike Hughes]

I am just getting started with the 300 Blackout. There is very little data available for this cartridge and I cant find any data for cast loads. I think there is several members here that shoot the 300 blackout and I was hoping some of y'all would share some cast load data. I will be starting with boolits ranging from 150gr to 200gr. At this point, I'm not real concerned with the subsonic loads and would like to see what kind of accuracy I can get with supersonic (was thinking 1500-2000 fps). I bought a lb of 1680 and a lb of lil gun (these seem to be 2 of the most common with the 300 Blk) I think some are using H110. The gun is a AR with a 16" CMMG barrel, Any input will be appreciated.
Thanks

[27judge]

i dont like to put powder charges on the open forum but... Im having excellant results with the rcbs sil. bullet 180 grains with 17- 17.5 1680. Also use the noe 311299 202 with almost the same results and 15-16 gr 1680 1 inch groups at 50 yards i have a 16 inch cmng also. the only powder i can seem to get to work is 1680 2015 is almost as good but groups are not as tight blue dot 4198 and lit gun would not shoot in my gun tks ken

[DeanWinchester]

I've had very good grouping with a 155g Lee over 7.0g of Universal in my bolt action. I've also had very nice luck with a 247g MIssouri bullet over 8.0g of Unique. I don't know if these loads are safe in an AR or other guns, but I'm not in the least worried about pressures for this cartridge in my bolt rifle, a Savage 110.

[Jailer]

I've also had good luck with the Lee 312-155-2R air cooled running 16.2gr of H110. Runs about 1850 FPS with great accuracy. Anything faster and accuracy starts to fall off.

I have some that I water dropped to see if I can push them a little faster but I haven't had a chance to load them yet.

[HodakaGA]

http://castboolits.gunloads.com/showthread.php?t=166595

Here are my results with a 311299, about 210 gr. lubed and checked. I've settled on 16.5 gr. of WW680, 17 gr. was giving a little pressure signs.

I subbed my version of Ben's Red on the next batch and got an even 1700 fps with 16.5 gr. of WW680. Of course it was a different day, different alignment of the chrono, etc. A 25 yard zero gives me point blank to 175 yds w/o being over 3" high or low with this load.

WW680 should be very close to AA1680, reduce and test in your rifle.

I also want a larger sizer of at least .310. I get just a little leading with my 50/50 mix at .309. Pretty easy cleanup though with a dry brush, then wet soaked patches w/Kroil.

[Mike Hughes]

Thanks to you guys for sharing your data and results. This will really help me get started with this cartridge. I looked all over the net and just not much info to be found.

[DeanWinchester]

For the sheer fun of it and no other reason, I'm going to work down [instead of work up] a load using some 100g RN cast bullets I have. I'm going to see how slow I can safely push them and maintain accuracy. I'd like to get them down to about 700 or so. Maybe 4.0-5.0g of Universal to start and then start easing down.

[RU shooter]

Don't be afraid to experiment with some slower powders like Reloader7 and H4198 I had very good luck with both ,Velocity wasn't as fast as with lil gun but the accuracy was there with cast bullets in the 150-200 gr range. Somewhere around 16-17 grs was my sweet spot with both

[DeanWinchester]

RU is right.

RX7 works great. One of the best groups I have managed so far was a 157g cast bullet over RX7

[gds]

I use almost exclusively A1680 for cast and jacketed bullets.

[xacex]

I stopped using H110 for blackout due to pressure issues. Lilgun works much better. Now my brass last longer than 2 reloads. It works out well because I use it for the Beowulf too.
16g to 16.2g of lilgun under the Lee 155 311 2R is working well. In fact it shoots better than the 150g sierra bullets with the same charge.

[Sethum30065]

I'm starting a 300blk build and this will greatly help. I am just getting into reloading and trying to educate myself on casting.
P.S. Jailer, how about that 3 peat on friday!

[DeanWinchester]

For any of you bolt rifle shooters out there, a 100g tumble lubed Lee bullet over 3.0g of bullseye is a hoot! Shot fifty over the weekend and they were dead on at 25 and only half inch low at 50 yards.

[Mike Hughes]

Thanks again for sharing load data. Loading these with cast boolits is like venturing into unchartered territory. I usually wont load anything that is not published in a manual. I have been testing with the Lee 150 gr fn. Using 1680, Lil gun, and reloader 7.
Lil gun 16 gr 1910 fps
Re 7 16 gr 1510 fps
Re 7 17 gr 1680 fps
1680 16 gr 1520 fps
1680 17.3 gr 1658 fps

I would like to tighten up the 100 yd groups. I was thinking about slowing down the Lil gun (maybe 15 or 15.5 gr), increasing the 1680 to 18 or 19 gr. I would like to speed up the Re 7, but 17 gr is pretty full and not sure if I should compress it. I formed my cases from LC brass (mixed dates). I did not anneal the case but I have read that it improves accuracy. The Re 7 seems to have good potential, but what do you guys think about compressing that load? Do you think it helps to anneal the necks.

[captain-03]

Mike I am in the same boat as you ... just got the same upper you have. Got a wide assortment of 30cal molds ... time for some trials.

Keep us posted on your results.

[Jailer]

Got my water dropped rounds loaded up and if the weather holds out I'll be heading to the range shortly.

P.S. Jailer, how about that 3 peat on friday!

Magical. Terry's running an outstanding program and those kids have a ton of heart. Obviously you're local to be paying attention to Ithaca football.

[captain-03]

Mike - what length are you loading the 150 Lee?

[Mike Hughes]

Mike - what length are you loading the 150 Lee?

I was seating the Lee 150 at 1.842. I have now switched my focus to the Lee 312-155-2r, New mold just arrived a few days ago. Seems to be a better profile for this cartridge. I am seating these at 2.04, still having best results with reloader 7. I will post my latest results shortly

[RU shooter]

I would like to tighten up the 100 yd groups. I was thinking about slowing down the Lil gun (maybe 15 or 15.5 gr), increasing the 1680 to 18 or 19 gr. I would like to speed up the Re 7, but 17 gr is pretty full and not sure if I should compress it. I formed my cases from LC brass (mixed dates). I did not anneal the case but I have read that it improves accuracy. The Re 7 seems to have good potential, but what do you guys think about compressing that load? Do you think it helps to anneal the necks.

The Lil Gun load looks good Why reduce it? 16 gr was the most accurate load with the RCBS 165 in my barrel , As far as the RE7 loads I couldnt figure it out with some bullets it shot real well at max capacity 17.5 gr and with another style of bullet almost the same weight it did excellent at 15-16 gr . So go up and down with it some .BTW my RP brass would hold about a full grain more RE7 than the LC.

[Jailer]

Well the results weren't as well as I had hoped. The best I got was still around 15.5 to 16gr of H110 with groups in the 2 1/2 to 2 3/4 inch range. I still have not been able to get any luck at all with Lilgun or 1680. I'm going to try some RE7 and see how that works out.

I did find the upper limit for the Lee 312-155-2R with 2 different powders. COAL of 2.060 with 16.5gr of H110 gave me ejector swipes on a few rounds and 17.0gr H110 popped a primer on the 2nd shot. 17.0gr of Lilgun popped a primer on the 5th shot with some pretty severe ejector swipes on a couple rounds. Both loads were right around the 2050 FPS range.

These were shot from my Savage Axis with a BFG 300 blk barrel.