Stretching/lengthening brass

[TexasMac]

I just finished lengthening 100 .45-70 cases using Tim Smith-Lyon’s swage plug & thought you might be interested in reading the article I just updated on stretching brass. The link is http://www.texas-mac.com/Lengthening_Sh ... amber.html

Wayne

[mdeland]

Wayne, the problem I have and never found an answer to, is case shortening. I've made a cast and measured my chamber, cut with a standard SAAMI spec reamer , nibbed out and trimmed to length and about six firings later they will be .010-.015 shorter. I have no explanation why this should occur as I do not resize.
I do use veggie wads and should probably try LDPE to see if it solves the issue but I would like to know why it is happening. I would think the brass would get longer if anything as it does in every other caliber I shoot.

[MikeT]

mdeland,

It has been my experience that once the brass fully fills out the chamber, there is no more shortening.

Keep on hav'n fun!
MikeT

[TexasMac]

Wayne, the problem I have and never found an answer to, is case shortening. I've made a cast and measured my chamber, cut with a standard SAAMI spec reamer , nibbed out and trimmed to length and about six firings later they will be .010-.015 shorter. I have no explanation why this should occur as I do not resize.
I do use veggie wads and should probably try LDPE to see if it solves the issue but I would like to know why it is happening. I would think the brass would get longer if anything as it does in every other caliber I shoot.

Mike,

Since you’re not resizing the only thing I can think of is possibly your case cleaning process. I have experimentally linked case shortening with lip peening which happens with ceramic media but more so with stainless steel pins. The peening process may not be enough to notice it after a cleaning but it’s accumulative over several cleaning. If you anneal after each firing as I do the shortening is more rapid but peening still happens without frequent annealing, it just takes longer. Once my case get a little short due to peening I use a swaging process with a drill rod inserted in a resizing die to flatten out the peened lip.

LDPE wads may counteract the problem since they tend to grip the walls much tighter than veggies and therefore tend to stretch the brass especially if the inside case walls are not real clean. But if your cases are real clean I doubt LDPE will offset the shortening. If you find that peening is not the root cause than I have no idea.

Wayne