Trimming Pistol Cases

[EddieCoyle]

I load handgun rounds for about a dozen calibers. Until now, I've never bothered trimming pistol cases to length.

However, I'm about to load up my first batch of .460 S&W Magnums. The brass I've collected (Mostly Starline and Hornady) varies in length. I'm going to load these hot with a slow burning "magnum" pistol powder (H110). Since I'm going to be roll-crimping the rounds, I want to make sure everything is the same before I start in.

Here's my question:

Should I trim to length before or after I resize? Does it matter all that much with a straight-walled pistol case?

 

[1903Collector]

If I'm not mistaken every reloading manual I have looked at states you should trim after you resize, that's the way I have always done it. If I measure my rifle cases before and after sizing I usually get two very different numbers so sizing first brings everything back to spec. The only exception would be those who neck size only. But with a straight wall pistol case, not to sure. I'm sure someone else can chime in who knows for sure.

My two bits.
O3C

 

[Dick]

We had a thread on a similar question a while back. I'd always been under the impression that a rifle case would increase in length when resized due to forming it back to specs and the expander ball dragging on the way back out. There were some other opinions, so I carefully miked some cases, resized them, and found that there really wasn't any stretch and some of them actually got shorter (!). So, I suspect it doesn't make a great deal of difference when you trim your pistol brass, but I'd be inclined to resize first on the assumption that that if the length is ever going to change enough to matter that's when it's most likely to happen.

 

[jhrosier]

I've always trimmed first and never gave it much thought.
I trim to the "miminum" length, which is usually about .010" shorter than the nominal length.
My only question is, what size is the trimmer pilot and will it still fit in the resized case?

 

[Jose]

Doing it after resizing is the only way to guarantee than case lengths are all matched.

ETA: If reloading for bulk plinking or SHTF ammo, case length variations within spec are immaterial. If reloading for match use, trim after sizing.

 

[Dick]

My only question is, what size is the trimmer pilot and will it still fit in the resized case?

That's a good point that I hadn't thought about. With my RCBS trimmer and pilots, the fit is just right AFTER resizing (rifle brass, that is) - i.e., the pilot is a bit snug in the case mouth and doesn't allow the case to move around while it's being trimmed. I've never tried it before resizing, but I suspect things might be a bit sloppy. Again, probably one of those things that doesn't matter a whole lot with pistol brass.

 

[Jose]

Use an LE Wilson trimmer and there is no reason to worry about pilots and collets. A superior system IMO.