joeb33050
12-30-2006, 07:47 AM
The Nov./Dec. 2001 ASSRA Journal article: “The Importance of Case Length in Cast Bullet Accuracy”, stated that short cases yield less accuracy than cases close to maximum length with cast bullets.
I worked with a 300 WM, case length is published as 2.620", my rifle would accept a case length of 2.648. I made cases from 300 H&H, then 375 H&H; ended with case length of 2.646". I found no accuracy difference with a longer case.
The 30/30 case length is 2.039", trim to 2.028". The 30/30 Martini bench gun chamber case length is 2.080". The M54 30/30 chamber case length is 2.115". All cases I've measured are less than 2.039" long once fired, some a lot shorter.
I've been working with Buffalo Arms "long" 38/55 brass, making long 30/30s. So far there's no accuracy improvement with the long cases.
I made 223 cases from 222 Magnum brass to get "long" cases to match the chamber, with no accuracy improvement.
I've checked case length and chamber case length on a number of rifles over the past years, and find in all cases that the chamber is longer than spec, and all brass is no longer than the trim-to length as bought. After trimming square and to the minimum length of the majority of the lot, cases end up substantially shorter than the chamber. 32/20 cases for the Contender were very short.
Jeff Bowles mentioned that he makes 308 Win cases that are .0015" from the end of the chamber, that this enhances accuracy.
Frank Marshall, in "Neck Length And Accuracy In Cast Loads", TFS March April 2005, page 174-9, mentions seeing substantial accuracy improvements when using cases with "long" necks-not to exceed the chamber case length of course.
Duplex mentions that short cases can cause chamber ringing.
If making cases that match-the-chamber-length-less-a-bit improves accuracy for anyone out there, I'd like to know the details and the accuracy change. If it works, it is one of the easiest and cheapest changes to make. I'm hoping to find out that it works, and "how to".
Thanks;
joe brennan
I worked with a 300 WM, case length is published as 2.620", my rifle would accept a case length of 2.648. I made cases from 300 H&H, then 375 H&H; ended with case length of 2.646". I found no accuracy difference with a longer case.
The 30/30 case length is 2.039", trim to 2.028". The 30/30 Martini bench gun chamber case length is 2.080". The M54 30/30 chamber case length is 2.115". All cases I've measured are less than 2.039" long once fired, some a lot shorter.
I've been working with Buffalo Arms "long" 38/55 brass, making long 30/30s. So far there's no accuracy improvement with the long cases.
I made 223 cases from 222 Magnum brass to get "long" cases to match the chamber, with no accuracy improvement.
I've checked case length and chamber case length on a number of rifles over the past years, and find in all cases that the chamber is longer than spec, and all brass is no longer than the trim-to length as bought. After trimming square and to the minimum length of the majority of the lot, cases end up substantially shorter than the chamber. 32/20 cases for the Contender were very short.
Jeff Bowles mentioned that he makes 308 Win cases that are .0015" from the end of the chamber, that this enhances accuracy.
Frank Marshall, in "Neck Length And Accuracy In Cast Loads", TFS March April 2005, page 174-9, mentions seeing substantial accuracy improvements when using cases with "long" necks-not to exceed the chamber case length of course.
Duplex mentions that short cases can cause chamber ringing.
If making cases that match-the-chamber-length-less-a-bit improves accuracy for anyone out there, I'd like to know the details and the accuracy change. If it works, it is one of the easiest and cheapest changes to make. I'm hoping to find out that it works, and "how to".
Thanks;
joe brennan