9mm trimmer pilot dia.???????????

Inside case dia. is .347 and trimmer pilot is .350-.351 depending on brand (I have two) projectile dia. is .355 why the mega spread??? How does one trim new cases?:???::?

The 9MM is a trickey round to load, ive seen cases with differnt lengths made by the same company, ive seem cases with different inturnal volumes. With that said most manual gives the Max length and the case trim length of the brass. You should check the length of the two different brands of brass you have. I dont use any brass that is shorter the case trim length

I can't remember ever needing to trim a pistol case, but (after checking) the .35cal pilot on my Lyman trimmer fits 9mm cases no problem.

Straightwall pistol cases don't grow much at all over many many loadings, and as long as you aren't stressing the neck by overexpanding and crimping too heavily, they generally don't need to be trimmed. .380ACP, 9mm, .38super, .40S&W, .45ACP, none of mine get long enough to need trimming even after 20 or 30 loadings. In fact, the primer pockets loosen or the necks split before they ever get long enough for me to worry about having to trim them. I can see checking all range brass for uniformity (I do), tossing also those that are too long, too short, or abused, and maybe in extreme cases sorting pistol cases by headstamp. Our last batch of 2500 9mm cases got tossed after 25 loadings, and they were still usable, but we stopped loading when it became much cheaper to buy them loaded. They were shot out of a variety of pistols, old and new. We haven't been saving 9mm range brass for around ten years, though I expect we'll be doing them again pretty soon.

Unless the cases are actually causing feeding problems in your pistol or extreme inconsistancy in performance (like if you are a bullseye shooter with the talent and a race gun to match it) I can see no reason to bother trimming them at all. Even my revolver cases don't need a lot of maintenence that way, either, though they never last as long as pistol cases because of the greater stress put on their necks by roll crimping. I can remember exactly once trimming a batch of 100 .357mag cases that I had been shooting redline loads in my Contender, but never cases I actually use in my revolvers, and it is not at all unsusal for me to get more than 20 loadings out of them.

So, back to why? Do you have a batch of really cheesy foreign brass, a pistol with an incredibly tight (or short) chamber, or some other not-very-common problem?

I should clarify, I am loading the 357 SIG it is a botttleneck case and it headspaces on the case mouth. Aren't strait walled cases "sesitive" to length due to seating depth and crimp ? I am working with "W" brass at this time and in 100 pcs. the length varies .8555 - .8635 . All my load data reads .860 min. and .865 max with not more than 20 pcs. within .002.

Casullman
Your working with the .357 Sig a bottle neck case in a Semi Auto pistol,i would sure watch the case length. The cases that are .8635 seem to fall with in the case specs. Case length effects the OAL which effects the pressure

That makes a lot more sense. Anything with a bottleneck is going to stretch and grow from sizing. I loaded .30Mauser cases for a few years at one point, so I understand the issues you're dealing with. In fact, I almost declared a national holiday when my friend had to sell his broomhandle it was such a pain to load for. I still don't get the small ID of the case mouth - .380 and 9mm cases are larger there (right around .350" after sizing) and I wonder if your sizer is not taking them down too far. I don't load for the Sigg, but that number is way too small and seemingly will result in working the brass more than I would think necessary and shorten its working life considerably. It sounds like you may have a slight problem with your sizer die and a call to the manufacturer might be in order to compare your numbers with their's.

Thank you both for your posts. I did some research and found that the .007-.008 spread from projectile to ID is correct . It is all about setback and neck tension (when isn't it ?) This cartridge is not for those who want a no brainer to crank out by the scads, at least not if ultimate accuracy is in mind. It is, at this time believed to headspace on the shoulder primarily and then the casse mouth this is where the real challenge is. I will be trying some Starline brass hopefully it is better quality and I won,t have to cull 50+%.