What Size Custom M Die for 44 Mag?

[Mal Paso]

How much neck tension should there be on a 44 cast boolit? I bought a set of plug gauges to go with my micrometers. The body of My Lyman M die is .4265 and the nominal inside diameter of a sized case ( Hornady Die ) is .426. That confirms my suspicion that the M die body was Not expanding the case at all. The shoulder wasn't big enough either and I was using the shaft to flair the mouth.

I am trending toward softer boolits and would like to get a new plug made.

My Boolits are .431 + .0 to .0003 . Suggestions?

[1hole]

"How much neck tension should there be on a 44 cast boolit?"

About a thou or just a tad more, any more than that simply stretches the brass and leaves the same amount of 'tension' (interferrence fit actually) on the loaded bullet. No matter how much smaller we make the case mouth all we are doing is making it more difficult to seat the bullets. The body portion of the M die is for jacketed bullets as well as cast, only the 'step' and flare matter much for cast. If your cast bullets are larger than the step then you would need the flare.

I've cast and fired a lot of medium to full power 44 and 357 mag. loads in the last 47 years. I've never found any need to size my cast bullets any larger than .429"/.357" because normal obturation insures they will fully obturate in any oversize barrel quite easily. (That's NOT true for light weight bullets fired with sissy charges tho.)

[462]

Mal Paso,
My .44 Specials require rather fat boolits, and the standard M-die plug wasn't working to my satisfaction. I had a machinist make one to my specifications and all is well. Had him make plugs for other calibers, too.

The only problem: His taste in beer is magnitudes more expensive than mine.

[Mal Paso]

Thanks 1hole. I'm glad I asked because i sure wasn't looking at it like that.

462 Specials are all I'm allowed for Silhouettes and I'd love to make them as accurate as the mags.

The family includes a Colt with a .430 groove and a Ruger with .432 throats .431 makes everybody happy.

[462]

Mal,
Sorry, I overlooked your first sentence. The custom plugs' first diameters are .002" under boolit dimensions and are the same length as the boolits, while the second diameters are .001" larger.