300 Win Mag brass

[Divehobo]

Started prepping about a hundred pcs of 300 Win Mag brass and found a few, about a dozen below typical 2.610 trim length. Range is from 2.600 to 2.608, how safe is it to load them?

I have cut the first 85 or so to length and figure it will give consistency and allow same crimp from one to the other.

What is the up or down side of trimming the remaining cases to the same shortened length and running through the rifle?

[J-cat]

You should find the actual length of your chamber and then you'll realize you'll never have to trim ever.

[Divehobo]

casting chamber? go/no go gauge? o.k, I'll bite, how to I determine the length of a rifles chamber?

[J-cat]

http://www.sinclairintl.com/reloading-equipment/measuring-tools/case-gauges-headspace-tools/sinclair-chamber-length-gage-prod32925.aspx

[J-cat]

Just so you know, my .300 Win Mag chamber is 2.673" long and Hornady brass grows .001" per firing.

[Divehobo]

With a max overall length known, you can fine tune your reloads specific for your chamber. Kind of like only neck sizing for fire formed brass vrs full length resize. With growth of case length during fire session, a trimming of some kind would be required to keep consistent between one cartridge to the next.
Thanks for the help with this.

[J-cat]

Have you seen case length variance affect accuracy? How consistent should they be?

[Divehobo]

Lol, never compared as have always trimmed to same length. I will most likely load all my "shorts" and do a side by side comparison at some point. Thinking all my worries were for naught. Now you have me re-thinking all the leg work and prep I have been doing before running the reloader. Prep work kept the rifle rounds confined to a single stage, possibly something else to bypass.

[fguffey]

casting chamber? go/no go gauge? o.k, I'll bite, how to I determine the length of a rifles chamber?

It is possible to cast a chamber and make very accurate measurements from the casting. It is also possible to determine the length of the chamber by forming cases.

F. Guffey

[fguffey]

Lol, never compared as have always trimmed to same length.

I want my cases to cover the chamber. I do not assume my chambers are go-gage length. I size cases to off set the length of the chamber. Everyone else bumps .002".

One chamber has an additional .016" case length from the shoulder to the case head. I form 280 Remington cases for that chamber by adjusting the die off the shell holder .014".

It would be mindless to trim the cases to 'trim to length', I add .014" to the length of the case from the end of the neck to the case head.

I make chamber gages out of shot out barrels, when cutting the barrel is is easy to see the effect a short case has on chamber when gas cut.

F. Guffey