Hopefully a simple question

[22to45]

I have had good success with my 45 mold for the 45/70, and I took that confidence to my 30 cal Lee 200 grain GC mold. I have not had much success, on the first run I could barely keep 3 bullets on a page at 25 yards. On measuring the bullets they are a bit undersized, they are about .307 as cast. As much as I would love to blame Mr Lee's mold, I suspect something in my technique. I am casting WWs with a small amount of tin added. Thanks in advance.
Allen

[geargnasher]

My first question involves your measuring technique, not your casting technique. I have a very strong opinion that a good, 0-1" micrometer is the only accurate way to measure boolit diameter.

My second question is what is your gun's groove diameter, cartridge name, load, etc.

Give us something to go on.

Gear

[WILCO]

Add a little more tin, switch up your alloy blend or try to beagle your mold.

[geargnasher]

Tin ain't gonna make .002"+, or any other lead alloy, for that matter. Beagling might, but I have my doubts that the mould is really dumping .307" boolits. It would explain the tumbling, however.

Gear

[Bret4207]

As usual Gear hit the correct points. We need more info.

[sqlbullet]

My Lee 200 gr mold drops 'em right under .310. My mold got the cavity polish with a cast bullet coated with toothpaste driven by an electric drill. I can't imaging it really made it that much bigger.

You don't mention quite a few things. Are these bullets being run through any sizing die? How are they lubed? What gun and load are you using?

I have had great success with this bullet in my M1 Garands in 30-06. Both guns slug .3085. I size .310, and the die will just wipe the tall spots off the sides. I lube with Felix lube to which I added a blue crayon or two for color. Hornady gas checks. I load them in once fired HXP brass, sized and trimmed. I have tried the following loads with success:

42 grains H4831 with 1/4 sheet TP filler.
32 gr and 34 gr of Varget with .75 gr dacron.
32 gr and 34 gr of Reloader 15 with .75 gr dacron. This load shot OK, but didn't have enough port pressure to run the action reliably. I have loaded some test loads with 36 gr, but haven't gotten out to try them yet.

All loads are seated to the crimp groove, and crimped with a Lee Factory Crimp Die.

Please give us the rest of the details about your load, and we might be able to provide better feedback.