lyman 49th

joshmb1982

why is it that they give 2 different lengths for each cartridge in this book? or is it the same in all books? In ever caliber ive looked up the diagram with show the length of the shell being 2.015 and then written in the specs it says trim to length 2.005. always in every caliber there is a .010 difference in the "trim to" length and the diagram length.

Willys 1948

Longer one is factory spec. You don't want to trim any shorter than "trim to length"

Willys 1948

In addition, I don't let my cases get very much longer than factory spec for pressure reasons. That's just me.

Willys 1948

Longer one is factory spec. You don't want to trim any shorter than "trim to length"

Ambrose

Actually, the diagram length is the maximun length. Factory cartridge cases are shorter that that; sometimes shorter than the "trim length". The reason for trimming is that, when cases get too long, the case mouth will hit the end of the chamber and force a crimp against the bullet and, of course, hold the bullet, driving up pressure. Factory loads usually are crimped but that crimp is easily pushed aside since it is not held by the end of the chamber. Lyman (and you are right in that other books recommend it, too) advises you to trim when your cases reach or exceed the maximum length or, as you describe it, the diagram length. For what it's worth, I recommend it, too. I hope this explanation helps.

joshmb1982

im splitting the difference when i trim to length. if the diagram says 2.015 and the description says 2.005 i trim to 2.010.some go as low as 2.006 and some as high as 2.013. im not checking every single case though. probably 1 in 20 or so.

Ambrose

im splitting the difference when i trim to length. if the diagram says 2.015 and the description says 2.005 i trim to 2.010.some go as low as 2.006 and some as high as 2.013. im not checking every single case though. probably 1 in 20 or so.

That's fine. The only reason for trimming .010 is so you don't have to trim as often. The Wilson trimmer I use holds quite close tolerances but your method should be completely workable.

charliemeyer007

Not every one is .010 to trim. See 30 carbine. For your best ammo you should doing every shell the same. A loading block and cartridge box helps. So it's the total amount trimmed not the number of times trimmed thats important. As explained in the book, that brass has to come from somewhere, namely right in front of shell head. My well used brass gets low intensity lead bullet loads until they fail or I need to make something else out of them.