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Bill Akins · October 30, 2013, 04:53 AM

Yep, you grasped it correctly what I was asking Doc. I know on some cartridge cases that can be trimmed to replicate the shorter length of other cases, and have the same exterior dimensions as those shorter cases (except for length), that sometimes the interior thickness of the head of the case that is trimmed down shorter, is thicker than the original shorter case's head that it was trimmed to work as. And that would cause a volume difference in powder between the two cases, even though they appeared exactly the same externally after trimming the longer one down. I can't remember exactly which ones, but I've run into this case head different internal thickness thing years ago when trimming down rifle cartridges to work (and sometimes fireform) in handguns. Been years since I messed around with that, but do remember there being differences in the case head thicknesses.

I've seen this exemplified in photos of cases that were section cut to show the differing thickness of the internal head area of one case, while the same section cut of another similar case had a different internal head thickness. I was wondering if since the .38 special and .357 have higher pressures than the .38 long, if perhaps the head area of the .38 special and .357 had been made thicker than the internal head thickness of the old .38 long.

Might be hard to eyeball it just looking down into the cases to tell if there is any difference. Only way to know for sure would be to section cut all three cases lengthwise and compare/measure the thickness of all three's internal case head area.

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October 30, 2013, 04:53 AM	#7
Bill Akins Senior Member Join Date: August 28, 2007 Location: Hudson, Florida Posts: 1,135	Yep, you grasped it correctly what I was asking Doc. I know on some cartridge cases that can be trimmed to replicate the shorter length of other cases, and have the same exterior dimensions as those shorter cases (except for length), that sometimes the interior thickness of the head of the case that is trimmed down shorter, is thicker than the original shorter case's head that it was trimmed to work as. And that would cause a volume difference in powder between the two cases, even though they appeared exactly the same externally after trimming the longer one down. I can't remember exactly which ones, but I've run into this case head different internal thickness thing years ago when trimming down rifle cartridges to work (and sometimes fireform) in handguns. Been years since I messed around with that, but do remember there being differences in the case head thicknesses. I've seen this exemplified in photos of cases that were section cut to show the differing thickness of the internal head area of one case, while the same section cut of another similar case had a different internal head thickness. I was wondering if since the .38 special and .357 have higher pressures than the .38 long, if perhaps the head area of the .38 special and .357 had been made thicker than the internal head thickness of the old .38 long. Might be hard to eyeball it just looking down into the cases to tell if there is any difference. Only way to know for sure would be to section cut all three cases lengthwise and compare/measure the thickness of all three's internal case head area. . __________________ "This is my Remy and this is my Colt. Remy loads easy and topstrap strong, Colt balances better and never feels wrong. A repro black powder revolver gun, they smoke and shoot lead and give me much fun. I can't figure out which one I like better, they're both fine revolvers that fit in my leather". "To be sure of hitting the target, shoot first and call whatever you hit the target". Last edited by Bill Akins; October 30, 2013 at 04:59 AM.