I kinda have a rookie question on trimming brass. I am surprised I have reloaded for a little over a year and haven't confronted this issue yet.
I have always gone by the Lyman manual on the trim to length on my 338 Lapua brass, which it says is 2.714 I believe. The Nosler manual says its 2.724 I think. Ok. Why the difference? Any particular length better?
My next question is about the "trim to length" vs "maximum case length". I understand that trim to length is the minimum and the maximum length is just that. So your resized brass needs to always be somewhere in between in length and never over the maximum. Gotcha.
Here is what I would like to know. I have always trimmed to the minimum length listed in the Lyman manual after each firing because the 338 brass never seems to stay under the trim to length after firing. What effect would it have on accuracy if I skipped trimming a couple loads and let it grow without reaching the maximum case length? This would inevitably not produce consistent lengths in my brass since some tend to grow slightly more than others per shot it seems like. Anyhow... thanks for any advice yall could throw my way.
What you need to worry about is growth changes between casings. Usually this occurs with test loads (lighter loads in the series won't work your brass as much), but it can also occur if you have two rifles in a cal. or something is wonky with your load. Differing lengths will affect bullet pull and will introduce a variable to your load. If they are growing similarly why bust your knuckles. Do the nasty when they hit max. length.
I HATE case trimming and only do so when they get too long. How long is too long? The reloading books suggest a length but in most rifle chambers there is plenty of room past that dimension to the end of the chamber.
If you used a custom reamer you can reference the working drawing of the reamer and determine the distance to the end of the chamber.
If you don't have access to the reamer specs you can purchase Sinclair's chamber length plugs and actually determine the end of the chamber.
I am rather picky. What I use is the lee hand trimmer after each fireing I deprime, then gator the pocket, tumble then resise. If for the range neck sise, seat the bullet 2 thou off of the groves. For hunting fl sise, seat to sammi specs and crimp.