How much can you size down. Comments Please.

[jh45gun]

Discussing this at an other forum
A guy bought a 10mm glock and wants to use heavier bullets than the 200 grain available bullets in .401 diameter. He wants to buy a mold for the Lyman 403169 .406 size bullet (40/65 Winchester) and size it down from .406 to .401. I think that is too much to size down is it? I told him it would be like taking a .457 bullet for a 45/70 and sizing it down to .452 for a 45 Colt. I told him I did not think it would work well. So will it or not? Personally I have my doubts I think that is sizing down too much. Plus who knows what it will cast out as might be even larger than .406.

[subsonic]

It will probably work if he uses a sizer that sizes the boolit straightly and his ammo fits in the gun. The things to watch for when sizing down are crooked sizing and reducing the crimp groove as well as the lube grooves to the point that they are non-functional.

Your example has been done successfully - the 340gr Lee .458 gets used in .45 colt and old Elmer himself was blowing up SAA Colts with .45-70 boolits and ground up FFF.

I think it might work, but if his Glock 20 is like mine, he want's .403" boolits anyway. The only hold-ups might be chambering if there is a long straight driving band section in front of the case that will hit the rifling preventing chambering as well as case web thickness might prevent deep enough seating to be able to get them in the magazine. I would be doing a lot more measuring before ordering that mold. 240gr is probably not going to fit in the case and magazine, but I might be wrong.

But I have to ask why when both Mountain Molds and Accurate Molds will custom cut whatever you want for a little more than that Lyman and it's a nicer mold to boot!

See Buckshot for a lubrisizer and push-through die.

[bob208]

i have done it before but in .002 steps. i have a mould for a .40-82 that drops a .403 bullrt. it go about 260 gr. it has been used in .38-40 for heavy bullets.

[paul h]

It depends on the design of the bullet i.e. width and depth of the lube grooves vs. driving band width, and the hardness of the bullet. The risk is that the bullets won't be sized concentrically, and the resulting bullets will have their lube groove capacity reduced and the bearing lenght increased. God help you trying to run a hardened bullet through a sizer reducing it that much.

It's one thing if one has a mold on hand and wants to try 20-50 bullets to see how they'll work. But if you have to buy a mold, might as well get a custom mold that will be exactly what he wants.

[jh45gun]

Thanks guys I will pass that on to him about the custom mould.

[JonB_in_Glencoe]

I started a thread on this topic a while back, maybe some of this info will help you out.
Jon

http://castboolits.gunloads.com/showthread.php?t=137277&highlight=RCBS

[geargnasher]

I missed Jon's thread, but sizing .005-6" is no big deal at all to do in one shot. The trick is to fill the lube grooves WELL in a boolit-sized die using a very viscous lube (two trips through under pressure to ensure no air pockets) and THEN cram them through a nose-first sizer like a Lee-style or Magma Star. The lube will not compress, but the lead will displace as the boolit is squeezed down, thus preserving the lube and crimp grooves. Might have to clean the lube out the crimp groove before loading, though, if using a boolit that needs a roll crimp. The 10mm shouldn't need any such crimp so no worries about a lubed crimp groove there.

I've loaded and shot a pile of Lee 340-grain boolits in .45 Colts, lubed in a .457" base-first die and then through a push-through Lee .452" die. Even the ancient single-cavity version of the mould that I have with the tiny, shallow grooves has no reduction in groove volume doing it this way. The later versions of the boolit have bigger grooves.

Gear

[bigboredad]

I would believe like the others it should work just fine. But if he wants to buy a mold any way why not buy what you want and save the hassle. Like others I would stear him towards Tom at accuratemolds .com He could get a 2 cavity aluminum for 92 bucks and exactly what he wants and he would probably get it just as fast as he would from any of the other mail order shippers.

[JonB_in_Glencoe]

I missed Jon's thread, but sizing .005-6" is no big deal at all to do in one shot. Gear

The thread I started was not exactly what "jh45gun" was asking, but some similar info about sizing and accuracy, and BTW Gear, you were the 6th member to post in that thread, so you didn't miss it. lol :lol: :lol:
Jon

[jh45gun]

Well the guy took your guys advice about Accurate Molds and contacted him.

[JonB_in_Glencoe]

He will be happy !

[subsonic]

Pass these links on to him:

230gr 10mm
http://singleactions.proboards.com/index.cgi?board=gallery&action=display&thread=8329

get them here:
http://cordercustomworkshop.com/

[jh45gun]

Will do