While back I read something somewhere about trimming cases, specifically bottle neck, and when they actually need to be trimmed. Being somewhat of a data geek, I decided to measure the chambers in my rifles (7mmRM, 2 different .22-250) so I would know when my brass needed to be trimmed as compared to automatically trimming according to published max case lengths and trim to lengths.
So I got some "chamber length gauges" from Sinclair and proceeded to measure my chambers. The process for creating a round to use these gauges is pretty simple so I won't go into that detail here. Interesting results I got; not what I expected to see.
Knowing that SAAMI chamber specs are minimums I figured I would see the chamber lengths on my rifles close to or slightly longer than these minimums.
For 7mmRM, the published max case length is 2.500; my chamber measure 2.548 checked and verified 3 times. For .22-250, published max case length is 1.912; one rifle measured 1.946 and the other measured 1.949. These were also checked and verified 3 times.
So what do I do with this info? Well, one of the reasons I decided to measure chamber length is because I've got some 7mm brass which after the last sizing had exceeded 2.500 in length. Plus some of my 250 brass is near 1.912 in length. So, I won't be trimming any of this brass soon and not sure if any of it will ever reach max length for my rifle chambers.
I know many if not most handloaders hate trimming their brass. By measuring actual chamber length we are able to find out when we really do need to trim rather than going by published max case lengths.
So I got some "chamber length gauges" from Sinclair and proceeded to measure my chambers. The process for creating a round to use these gauges is pretty simple so I won't go into that detail here. Interesting results I got; not what I expected to see.
Knowing that SAAMI chamber specs are minimums I figured I would see the chamber lengths on my rifles close to or slightly longer than these minimums.
For 7mmRM, the published max case length is 2.500; my chamber measure 2.548 checked and verified 3 times. For .22-250, published max case length is 1.912; one rifle measured 1.946 and the other measured 1.949. These were also checked and verified 3 times.
So what do I do with this info? Well, one of the reasons I decided to measure chamber length is because I've got some 7mm brass which after the last sizing had exceeded 2.500 in length. Plus some of my 250 brass is near 1.912 in length. So, I won't be trimming any of this brass soon and not sure if any of it will ever reach max length for my rifle chambers.
I know many if not most handloaders hate trimming their brass. By measuring actual chamber length we are able to find out when we really do need to trim rather than going by published max case lengths.