Casting for 300 BO - Page 1

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Posted: 8/29/2020 7:23:37 AM EDT

Looking to cast bullets to shoot subsonic from a suppressed 300 BO. I will be powder coating so I thought I’d look for a mold without lube grooves. This one from Accurate looks interesting.

Attached File

Thoughts?

Posted: 8/29/2020 8:25:20 AM EDT

[#1]

Use a hard alloy. I have had some baffle contact when shooting softer cast supers. I believe the fast twist rates deform softer bullets. The cast bullets I use now are so hard they ring when dropped on the table.

Posted: 8/29/2020 8:49:34 AM EDT

[#2]

I’ve been using range scrap of unknown hardness to cast 9mm, this will be the second caliber I have cast for so I’m pretty new to this. I have 5lbs of “Superhard” from Rotometals and some pewter I picked up at goodwill.

Posted: 8/29/2020 12:54:07 PM EDT

[#3]

Quoted:
Looking to cast bullets to shoot subsonic from a suppressed 300 BO. I will be powder coating so I thought I'd look for a mold without lube grooves. This one from Accurate looks interesting.
https://www.AR15.Com/media/mediaFiles/451123/6A6EB8AE-2CAB-47B9-B310-125329146356_png-1568104.JPG

Thoughts?

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Looks like a good design. Think I'm up to 4 Accurate molds now.

My 350 Legend mold is groveless, my first. Haven't shot any of the PC bullets I loaded yet.

Don't forget to get a set of Lee handles.

Posted: 9/6/2020 8:38:50 AM EDT

[#4]

I’m going through the process of ordering the mold from Accurate. I am at the point where they are asking for body diameter. Should I wait until my barrel arrives, slug it, Then order the mold, or can I assume it will be xx and order xx mold? I ordered an upper from PSA if that matters. Will be powder coating. I guess i will get a Lee push through sizer like I’m using for 9mm, unless there is a better way.

Posted: 9/6/2020 2:31:36 PM EDT

[#5]

If it were me, I would order your .311 mold now. Last one I ordered from Arsenal took 2 weeks from order date to arrival.

I size my 300 blk bullets to .310 with a Lee bullet sizing die I opened up. Buy .309 die convert to .310.

Every Lee sizing die I have 15-16, came sizing bullets .001 smaller than marked.

You have to size a bullet, and measure it to see. Then open it up from there.

With PC enlarging diameter is easy as you know.

Posted: 9/6/2020 5:20:17 PM EDT

[#6]

Thanks Dryflash. It says 3 weeks to get it but I’m assuming that is the maximum. Probably see it in around 2.
I also ordered a lb of Accurate 1680. If someone could point me towards a starting load I’d appreciate it.
Another question, I want to stay subsonic and don’t have a chronograph. How hard is it to tell by sound alone? I will probably shooting this thing some before I get the can.

I bet this thing will be extra super accurate, with Accurate powder pushing a bullet out of an Accurate mold and all.

Posted: 9/6/2020 11:32:08 PM EDT

[#7]

I don't shoot subs, but lots of info here; https://www.ar15.com/forums/Armory/300-Blackout-Master-Thread/42-385765/

Posted: 9/9/2020 6:23:24 AM EDT

[#8]

Quote History

Quoted:
If it were me, I would order your .311 mold now. Last one I ordered from Arsenal took 2 weeks from order date to arrival.

I size my 300 blk bullets to .310 with a Lee bullet sizing die I opened up. Buy .309 die convert to .310.

Every Lee sizing die I have 15-16, came sizing bullets .001 smaller than marked.

You have to size a bullet, and measure it to see. Then open it up from there.

With PC enlarging diameter is easy as you know.

View Quote

I was looking back at this post before ordering a sizing die and am confused. If the Lee dies run smaller than marked, and I buy a .309 (actually 308?), I’d need to open it up by .002. Why not buy a .311 (actually 310)?

ETA: FWIW, the two Lee sizing dies I have (357 &358) size exactly to what they are marked.

Posted: 9/9/2020 12:56:38 PM EDT

[#9]

Quote History

Quoted:

I was looking back at this post before ordering a sizing die and am confused. If the Lee dies run smaller than marked, and I buy a .309 (actually 308?), I'd need to open it up by .002. Why not buy a .311 (actually 310)?

ETA: FWIW, the two Lee sizing dies I have (357 &358) size exactly to what they are marked.

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That would work in theory, report back.

Posted: 9/10/2020 8:13:40 AM EDT

[#10]

I would see how your gun runs something with that style of bullet. Mine won’t feed Hornady subsonics due to the nose profile being too wide. I am certain it would not feed that bullet style either. If you are planning to use it in a bolt action I think it would be great.

BTW my barrel is a Ballistic Advantage so it is a decent quality barrel. It runs jacketed HP’s fine, and the LEE cast .300 BLK bullets great as well. I wish it would run something like that but I just don’t see it happening without a different magazine or feed ramp.

Anyhow- just a thought.

Posted: 9/10/2020 12:49:22 PM EDT

[#11]

Quote History

Quoted:

I was looking back at this post before ordering a sizing die and am confused. If the Lee dies run smaller than marked, and I buy a .309 (actually 308?), I'd need to open it up by .002. Why not buy a .311 (actually 310)?

ETA: FWIW, the two Lee sizing dies I have (357 &358) size exactly to what they are marked.

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Quote History

Quoted:

Quoted:
If it were me, I would order your .311 mold now. Last one I ordered from Arsenal took 2 weeks from order date to arrival.

I size my 300 blk bullets to .310 with a Lee bullet sizing die I opened up. Buy .309 die convert to .310.

Every Lee sizing die I have 15-16, came sizing bullets .001 smaller than marked.

You have to size a bullet, and measure it to see. Then open it up from there.

With PC enlarging diameter is easy as you know.

I was looking back at this post before ordering a sizing die and am confused. If the Lee dies run smaller than marked, and I buy a .309 (actually 308?), I'd need to open it up by .002. Why not buy a .311 (actually 310)?

ETA: FWIW, the two Lee sizing dies I have (357 &358) size exactly to what they are marked.

I have the .311. It sizes to .311.

I also have a .309. It sized to .309 until I opened it up.

I think mine have been about 50-50 on running true or small.

Posted: 9/10/2020 1:11:32 PM EDT

[#12]

FWIW OP, my Lee .357 sizes to .357, so still measure and confirm.

Posted: 9/10/2020 2:22:21 PM EDT

[#13]

Quote History

Quoted:
I have the .311. It sizes to .311.

I also have a .309. It sized to .309 until I opened it up.

I think mine have been about 50-50 on running true or small.

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Probably depends on tooling wear and who is operating the machine that makes them.

The take away is; size a bullet and measure it to see what you really have.

Posted: 9/11/2020 8:37:43 PM EDT

[#14]

Quote History

Quoted:
Probably depends on tooling wear and who is operating the machine that makes them.

The take away is; size a bullet and measure it to see what you really have.

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100% this.

I might add, alloy can make a difference as a harder alloy can have more spring back.

Opening them up is easy with some fine sandpaper, a small dowel rod and a cleaning mat laid across bench. Start small, go slow.

Posted: 9/16/2020 6:46:25 PM EDT

[#15]

Got my mold today, so only 10 days from order date!!

Shout out to Accurate molds!

Posted: 9/17/2020 12:06:54 AM EDT

[#16]

accurate makes great molds.

The NOE 247 grain is another great performer for subsonics.

Posted: 9/20/2020 8:08:12 AM EDT

[#17]

Put the new mold to work the other day then PCed them. Since I’m loading subsonic, I used the same range scrap ingots that worked for 9mm. I water dropped them after PC for good measure.

Attached File

I ordered the .309 bullet sizing die. Ran one through it and it mics at .309. Still need to slug my barrel to be sure what it is.

I have a lb of 1680 I was planning on using, but after more research it seems there are better options for suppressed subs. Looking at getting some N120. Where can I find load data for my 225 gr cast bullets?

ETA: barrel length is 7.5”

ETA2: Though it does not list cast data, I found this chart with load data for 1680

ETA2B: And this one for N120, but it only goes up to a 200 gr bullet.

Posted: 9/20/2020 10:42:05 AM EDT

[#18]

I’m using 10.7 gr of 1680 under a 247 gr NOE cast and PC bullet.

1680 is DIIIIIRRRTTTYYY in this application. I’d like to try something else, but snagged an 8 lb jug just before the start of the panic....

Posted: 9/20/2020 11:22:48 AM EDT

[#19]

I’m glad I only bought one lb of 1680. I found primers in stock and there was a stipulation that you had to buy powder. I didn’t take time to research because I was afraid the primers would sell out. I figure I can use it up making sure my bullets will feed (I’m a little worried the flat tip will be a problem). Plan on buying 8lbs of something better for when I get a suppressor for it.

I still need a few things to make this happen. I slugged my barrel (.309), and reamed my bullet sizing die to .310. Now I need an expander. Should I order a .309 expander or get a .310 and rely on the neck springing back to provide neck tension? Planning on an NOE expander unless there’s a better way.

Posted: 9/20/2020 1:33:31 PM EDT

[#20]

Quote History

Quoted:
I'm glad I only bought one lb of 1680. I found primers in stock and there was a stipulation that you had to buy powder. I didn't take time to research because I was afraid the primers would sell out. I figure I can use it up making sure my bullets will feed (I'm a little worried the flat tip will be a problem). Plan on buying 8lbs of something better for when I get a suppressor for it.

I still need a few things to make this happen. I slugged my barrel (.309), and reamed my bullet sizing die to .310. Now I need an expander. Should I order a .309 expander or get a .310 and rely on the neck springing back to provide neck tension? Planning on an NOE expander unless there's a better way.

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I use a Lyman M die for expanding.

Nothing to change. Tighten down expander, they don't come tight.

Then it's just a matter of adjusting. You want the short version of the 30 cal die.

I found the a Lee FCD helped my accuracy in 300 blk.

A light crimp, don't over do it.

The flat nose bullet will feed fine, feed ramp contacts bullets ogive.

I always open up and smooth the feed ramps on 30 cal AR's. Again don't over do it.

Posted: 9/21/2020 4:56:51 PM EDT

[#21]

I don’t see an M die listed for 300 blackout. Which one should I order?

If I go with the NOE, what size would I order for a .310 bullet?

Posted: 9/21/2020 9:52:33 PM EDT

[#22]

Quote History

Quoted:
I don't see an M die listed for 300 blackout. Which one should I order? 30 carbide die, the short one. The 308 die will not work.

If I go with the NOE, what size would I order for a .310 bullet? Never used one, so don't know.

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