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Texaslawman
10-02-2011, 06:54 PM
Hello everyone this is my first post here and I have a question or two. Im going to be using wheel weights to make the boolits for a .300 blackout AR. These will be for subsonic only so no gas check. Im planning on making 220gr+ boolits. Now my question comes from a thread on here where a group buy of a 247gr .311 mould. Now my question is the .300 blk is a .308 so should I buy a .309+ mould and size down to .308? I read a article saying I should make the bullets .309 for a .308 is this true or should I get a .308 sizer??

bruce drake
10-02-2011, 07:12 PM
size it to .308 and you may get leading issues. continue to do the research on this site or other casting forums and you'll find that rifles do better with lead bullets that are sized either
.309 or .310 to match the bore of the rifle's barrel better.

geargnasher
10-03-2011, 12:02 AM
Cast boolits usually, not always, but almost always work best when sized .001" or even a bit more over your groove diameter. Often this means getting a slightly larger expander spud to maintain .002" or so interference fit between the neck and boolit (neck tension). The Lyman "M" expander die for cast boolits in a 31 size works best for most .310-311 boolits, the 30 works best for .309" boolits. It will expand the case mouth in two steps and make seating the softer lead boolits more accurate and prevent lead shaving, especially with plain-based cast boolits. Neck expansion is an extra step needed with most cast boolit rifle cartridges.

Lyman and RCBS make sizers in .309, 310, and 311 if I remember correctly. You might find your gun likes .311" boolits depending on the throat dimension as Bruce mentioned.

Gear

mstarling
10-03-2011, 01:12 AM
Hi Tex,

My 300 BLK SS barrel was made from Douglas stock so I know it is 0.308". I size to 0.309" and am getting good stabilization and no leading with projectiles made from straight wheel weights and lubed with Carnauba Red.

The 9mm can won't be released to me until after Christmas I'll bet, so not doing that yet. Hope the cheap ammo issue is worked out by then.

Working up 220 SMK loads for the 30 cal can to hunt with this season.

Mike

selmerfan
10-03-2011, 08:55 AM
The only time one absolutely knows the measurements of a bore is after one slugs the bore or pours a casting. Everything else is hopeful conjecture and trust in the manufacturer. Glad to hear the .309" worked for you on the Douglas blank!

mstarling
10-03-2011, 09:42 AM
Point well taken. Should perhaps have explained that the Douglas folks are friends and checked the barrel for me as they are close by.

They also did a Savage .308 Win bbl for me several years ago and that also measured 0.308.