Neck Sizing after trimming ?

[warrenb]

I do understand that the general process is to size and then trim.

This morning I decided to neck size 100 cases. I had neck sized, trimmed and chamfered these cases last night. My reason being is that I do not have a runout gauge currently and I came to the conclusion that it is possible, however unlikely, that the process of trimming and chamfering the necks could effect their trueness (sp?).

The second neck size took 5 minutes and no lube was necessary. A simple process. I'm trimming using a Hornady cam lock. The cases grew another additional 1 thou btw.

I just wondered if anyone with a gauge has done any comparative tests on checking runout before and after trimming/chamfering and what were your findings?

Anyone who has not done any comparative tests think I'm a totally idiot and just waisting my time.

 

[curtmg]

Wouldn't trimming, properly done, square up the mouth, very nicely? I suppose you could mess it up chamfering, but I don't see it being a major problem. If you had a gauge, you could be sure, until you measure them, it's all just theory.

 

[warrenb]

Curt, I agree. It was probably a waste of time and an additional working of the brass for nothing. My thoughts were that we rely on the dies to form the brass as accurately and with as little bullet runout as possible. So could the act of putting pressure (however small) on the case mouth when trimming/chamfering distort the neck in any way. Like you said, if done properly its not likely.
But I thought I'd ask in case anyone else has done any tests.

To be honest I trimmed another batch of brass a couple of weeks back where I forgot to put the guide pilot in the trimmer head. I did not resize that brass afterwards and I got my best groups to date with it. So trimming likely has no effect on runnout.

 

[Pathfinder]

The second neck size took 5 minutes and no lube was necessary. A simple process. I'm trimming using a Hornady cam lock. The cases grew another additional 1 thou btw.

Anyone who has not done any comparative tests think I'm a totally idiot and just waisting my time.

While not having done the tests....I do believe you wasted 5 minutes that you will get back.

Ive personally never had to trim after neck sizing.

 

[Silverado]

You'd need to be pressing awfully hard on your chamfering cutter to cause runout!