Magma sizing dies

[1bluehorse]

Just had an interesting phone discussion with the folks at Magma (nice folks by the way) about their sizing dies...I have several of their dies for 357,44,45 cals...well, to make this short, I measured (with gauge pins) a couple of my .430 dies and found that they were in fact NOT .430 but .429..same with the .358 die, actually .357...my .458die..yep .457..the only sizing die that was actually what it said was my .452 die....when I called, the response I received was "well it depends on your alloy"....my response was alloy has nothing to do with the hole dia. .430 is .430....and I asked if the .431 die I just ordered yesterday would actually be .431....probably not....to get what I want/need they want a sample bullet...my bullets come from the mold at .4315 to .432+, so what the heck good that does them I don't know...what I want is a die with a .430 hole in it....or .358 or .458, or whatever I specify..does this make sense or not...are they (Magma) anticipating (depending on alloy) that the bullet is going to "grow" after sizing....?? I'm a bit perturbed..I would like to reiterate that the folks there are very helpful and polite....but they do have me confused.

[btroj]

Higher Sb alloys tend to bounce back after sizing.

Think of it this way. We size a pure lead bullet to .358 and it stays .358. We size a Lyman 2 bullet to .358 and it comes out .3585 or .359.

Happens all the time.

[MarkP]

It is due to Spring back, dictated by the elastic modulus of the mat’l . Elastic deformation to plastic and back to relaxed state.

[1bluehorse]

Higher Sb alloys tend to bounce back after sizing.

Think of it this way. We size a pure lead bullet to .358 and it stays .358. We size a Lyman 2 bullet to .358 and it comes out .3585 or .359.

Happens all the time.

I understand this, and like most here I use WW plus a bit of tin and allow for this in what size die I order... I just went and mic'ed some 45 colt bullets that I sized through the .452 size die (that's actually .452 and was told by Magma that was unusual) and they measured .4523 (my Rugers have .4525 throats and a .451 bore and this is the size I wanted).....the 44's that I ran through the .430 size die measure .4293.....(one of my 44's has .430 throats and .429 bore, .4293 is NOT what I want, my old SBH has .432 throats and a .430 bore and that's why I ordered a .431 die) I'm purely guessing on this but if I had ran them through a .430 size die that was ACTUALLY .430, they may have been at LEAST .430...I would rather them be a bit larger than smaller...MY opinion is that if I order a sizing die at .430 or whatever, that's what I want, the dia. stated...I don't want the manufacturer determining what "they think" I want....I know what I want....I suppose I could order a .432 die, maybe it would be .431...[smilie=b:

[HATCH]

My Lathesmith dies all measure correct.... We live in strange times in deed...

[1bluehorse]

Here's the latest from Magma....I called and talked to a fella named Eric, very nice guy....asked him if I sent my (undersized to me) dies back to them if they would hone/ream, whatever, to indicated size....he says, sure, if I send them a sample of my bullet....told him not necessary, just make the die actual size....he said it won't come out that size, I said what won't come out that size...he says the bullet....told him not to be concerned about that, I had that covered, I just want the DIE to be the dia I ordered...he says you bet, send em' in, just send along a note saying I want the DIE inside diameter to be the actual size...so when you order a die from them, they evidently make the die to make a BULLET that size unless you specify you want the diameter of the DIE that size....I don't understand that but I'm not in the sizing die making business so what do I know...anyway, nice folks, easy to work with....AND I ordered the .431 die also, but noted that .431 was the ACTUAL DIE size I wanted...:lol: