Hello all. This is my first post and am new to reloading. Before starting my new hobby, I have spent considerable time reading, researching, reading this forum, etc. I intend to load .45 ACP, 9mm, .223 and .308 Win.
One common theme or opinion that I have found here and elsewhere, is that handgun brass usually does not require trimming. Also read numerous accounts of the brass contracting rather than expanding. Not sure how true this is, but decided with the number of times I read the same opinion, that it must be true.
Recently, I began my project of reloading .45. Upon inspection, I have found that my average (once fired) casings are .93+/- as opposed to .898. Clearly, they must be trimmed.
My actual question is: Is this more likely a result of the ammo brand (Federal) or could it be the gun (Sig P220)? I guess the third possibility is all those people who said they've never trimmed .45 are full of crap.
Any opinions, tips, or other info will be appreciated.

This may not be much help but I never trim pistol(straight walled) brass. As far as measurements I have not bothered to measure any also. I can say that they all work fine for me. I load 38sp/357mag/44mag/454casull/9mm Luger/9mmMak/45ACP pistol brass. I also do not sort according to headatamp. I DO sort out the small primer pocket brass to load seperate from the large primer brass. OR just sell/trash the small primer brass.

The length of your chamber is greater than your ammo. Dissassembly your auto pistol and check the longest cases in your barrel. There is no point in trimming brass just to make it match the book. All it needs to do is fit your chamber.
The minimum lenght of a 45 ACP chamber is .898.
The max lenght is .920. You barrel will be some where between these two dimensions. Both are longer than the book trim lengths of .893.

SAAMI loaded ammo case length is allowed to be .898+.000-.010.

You will find your brass shortens when fired and then lengthens when sized. It oftens quits moving so much after the first firing.

The only problem I have encountered with straight walled pistol loading, as far as case length, is when the cases are of random length because that really throws proper bullet crimping into chaos. I eventually started using one headstamp for one caliber so that their case length is uniform, but really have no idea what that length is, because it really doesn't matter.

I'm with those that have never trimed straight walled pistol brass. If I encountered random length stuff like LD mentioned then I would.

Thanks all for your responses.

quote:

Originally posted by BarneyC:
I have found that my average (once fired) casings are .93+/- as opposed to .898.

Are you measuring a sized case?

If so, insert the empty sized case into the mag of the SIG220. Make sure the case is fully to the rear (like you would when loading a live round).

Now with the slide of the pistol locked back, insert the magazine like you were loading a mag with live ammo. Press the slide release and allow the slide to go freely forward (do not ride the slide). Does the case fully chamber? If it does, don't worry about trimming.