Case trim length

I bought 140 Nosler 260 cases in good condition other than the fact they were sized to 7mm08. They have been trimmed by the last owner to anywhere between 2.010" and 2.030" I have annealed a few and sized them. Should I just find the longer ones and make a batch the same? These are hopefully going to be my good brass for target. Maybe I just eave the shorter ones till they grow after a few firings. Or should I just trim them shorter?

The trim length for the 260 Rem. is 2.025. Once you resize the cases to 260 Rem. I would trim the long ones to 2.025 and let the shorter ones gain length with firing till you could trim them all the exact same length. Good Luck and Happy Shooting.

That would be nice but most seem to be around 2.015". Some are even at 2.005".
I didn't really want to have to fire them a few times before they become good. Wonder if I can fit an expander ball in my neck sizing die and squash them a bit longer. I have other brass options. PMC, PPU, Winchester, Remington and some brand new Lapua 308 brass. This is the only 260 head stamp I have though.

try measureing 1 then run it into a fl die then measure again. Did it get longer, or stay the same oal?, If it got longer then I would anneal them all and fl size them all. See if that will bring you closer to your oal that you want. If that did not do any good then I would measure them all then trim all to the same length as the shortest 1. From there you will at least have an equal oal to start with

You may already have wasted more worry than you 'saved' in money.
Rake em all into the trash & start with new cases..

The neck length is roughly 260 thou, so a trim variance of +/- 10 thou is only a +/- 3.3% difference in bullet contact area. That's good enough for what I do, but if it bothers you, just trim them all to the shortest length.

Trimming all to shortest length is same as trimming all to wrong length. And trim length is not about bullet contact area. It's about quick neck sealing, and mitigation of carbon buildup at chamber end.
That carbon sooting on your extracted case neck/shoulders represents a sample of what you leave in the chamber. This building and effectively reducing length of the chamber.
When you trim too far from chamber end you setup a lower/easier angle for this blowback to make it's way around necks, reducing sealing consistency, and potentially increasing SDs. Interference with case mouths expanding to carbon buildup can cause step changes in MV/pressure.

When you fire form cases the shoulders normally gain a bit of angle, which pulls necks back, further away from chamber end. So if new cases fit the chamber it makes sense to hold off on trimming until cases are at least formed to what they will be. From here you should consider case design and your planned sizing, for how often you'll need to trim & choose a value closest to -5thou to -10thou of YOUR ACTUAL chamber end(as measured)(not book)(forget any book).

I check this post since I posted on it.
With all the lengths you state these cases are, I wonder if they may have been run through some expanding operation that changed the shoulder angle and the length in expanding the neck. If a proper lube was not used or a hit and miss application of lube may have caused this too. Or the cases could have had no anneal, Or uneven anneal process before expanding that made it worse.
Would it be worth the cost if you have to fire form them to your rifles chamber? Would the fire forming of these short cases damage your rifle chamber or barrel?

No Pun intended. You may just have to bite the Bullet and buy a new supply of cases and start anew. May be the cheapest and less worry in the long run. Good Luck in your cure for this problem.

I'm with Mike, just sell them and move on.
To much variance and work to get them back to .260.
I would buy a Sinclair chamber gauge and run a new batch with the length as long as I could.

Perhaps your best option.

Mikecr said:

You may already have wasted more worry than you 'saved' in money.
Rake em all into the trash & start with new cases..

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