Case trimming- how many times?

[Varmint Hunter]

Trim back back from max and it will be fine.

The whole point was to NOT trim back from max unless needed.

 

[milboltnut]

The whole point was to NOT trim back from max unless needed

Kinda cutting close looking with a bore scope, don't ya think? Trim back and measure as you go seems best

 

[Varmint Hunter]

Kinda cutting close looking with a bore scope, don't ya think? Trim back and measure as you go seems best

Not really.

Without actually looking or measuring your actual chamber length you don't know how close or far your case mouth is from the chamber end. You can't just assume that you know how a chamber was cut. If a case was already .010"-.020"-.030" or more from the chamber end it would be counter-productive to cut back another .010" because a reloading manual suggests it.

Sinclair makes a gauge specifically to determine this measurement. However, for those who have a borescope they could just look at the available space and make a determination as to whether or not they need to further trim the case. It's a tip I picked up here on LRH and it makes a lot of sense.

 

[QuietTexan]

Just something to think about.

Yup, no need to go crazy trimming, especially if it's a case that doesn't grow a lot because of the shoulders. It's an over-used process that, to Mike's point, is typically indicative of another step in the process not being optimized.

I don't choose cartridges that force it (something like a 30-06), and I don't FL size.

I load a lot of 30-06, which can grow rapidly and I do trim it - but specifically because I can hit the end of my chamber before the brass stabilizes. That would be a bad situation, jamming the bolt down aside it's one step closer to accidentaly grenading the rifle by crimping the case. But I rarely if ever trim back anything with a 30-40* shoulder other than uniforming length once the cases stabilize.

In the context of precision bolt action loading, cases really just don't grow that much for a lot of chamberings. If they don't grow why cut them? If I know the spec to the end of the chamber why trim off more than needed? I'm taking all this time to set shoulders and necks carefully, minimal brass movement all around, why start cutting chunks off the end of the neck. Goes against a useful way to adjust bullet seating also, which is length of neck sized. Some cases you don't have a caliber of neck to work with in the first place, so why knock a few hundredths off an already short neck if you don't need to.

Other situations - yeah sure go nuts and trim it back to min if the goal is reliability. When loading for an AR/an action that doesn't cam, loading mixed cases or pickup brass, forming cases, there are a bunch of situations where uniforming cases is more important than chasing absolute precision. Small base FL die, trim to min, run it until the neck splits. RCBS goes all on this with the X-Die - comes in small base, you trim once and you're done. All-in-one maximum resizing in one die.

 

[milboltnut]

If a case was already .010"-.020"-.030" or more from the chamber end it would be counter-productive to cut back another .010" because a reloading manual suggests it.

And what sense does that make? If it is already that length then after bumping back the shoulder it wouldn't grow anyway.