I shot centerfire pistol matches for years, from around '73 till late 80's, and trimming was never a topic among the high mucky-mucks. I am still shooting WCC 72 & 73 brass I picked up at McKellers Lodge at Bragg in '74, and trimming is just not an issue. I trim bottle necked rifle brass religiously, but never pistol cases like the 45 or 9mm or any other straight wall case. Ain't no gold in that hole, Luke...

Some years ago, Charles Petty did an article for American Handgunner, I believe, that looked at accuracy in the .45 ACP for sorted brass versus unsorted. Brass was sorted for length. Petty had long maintained that sorting made no difference. He used a match 1911 mounted in a Ransom Rest. His testing did show that he had been incorrect and that the sorted brass did shoot better in a match tuned 1911. But not by much. For the 50 yard line where only 30 rounds were required for the full 2700, it was worth the effort, but for the 25 yard line he couldn't recommend the effort.

My guess is that for your application, it won't make a bit of difference.

quote:

Some years ago, Charles Petty did an article for American Handgunner, I believe, that looked at accuracy in the .45 ACP for sorted brass versus unsorted. Brass was sorted for length. Petty had long maintained that sorting made no difference. He used a match 1911 mounted in a Ransom Rest. His testing did show that he had been incorrect and that the sorted brass did shoot better in a match tuned 1911. But not by much. For the 50 yard line where only 30 rounds were required for the full 2700, it was worth the effort, but for the 25 yard line he couldn't recommend the effort.

That was one gun, one test. It is doubtful it would be repeatable with another gun & load. There is sorting brass & sorting brass. Number of times fired will matter as much as headstamp.

Here is my "scientific" test results. I would load a bunch of rounds and, occasionally sort them by head stamp. The following shows my accuracy results (in most cases, I had more mixed-case rounds than matching cases, so the blanks represent where I ran out of that load).

.45 Auto:
Loads made at same time and then sorted by head stamp
Groups at 25 yards
matching mixed
1.94 1.29
— 1.69
— 2.81
2.97 2.09
— 2.44
1.38 1.81
2.25 2.41
2.00 1.59
2.22 2.88
2.72 2.00
3.91 2.22
1.44 1.88
3.38 2.50
1.38 1.75
2.44 2.69
3.13 2.13
3.38 2.31
— 2.44
— 3.13
1.50 2.31
2.44 2.44
2.81 2.44
1.88 1.75
2.56 1.97
2.69 2.13
2.31 1.16
— 2.06
— 2.19
— 2.75
1.75 1.59
2.25 1.69
1.94 2.19
2.78 4.81
1.84 1.38
— 1.66
3.88 2.03
3.44 2.69
3.50 2.69
2.56 3.22
2.00 1.38
2.56 1.69
2.75 1.56
1.50 1.44
3.00 1.53
— 1.35
— 1.40
— 1.60
— 1.65
— 1.70
2.44 2.50
2.38 1.22
2.47 2.06
2.75 2.13
3.31 2.63
2.19 2.03
2.25 2.88

2.48 2.11 Avg
0.66 0.63 S.D.

0.002711 accept null hypothesis
So, the mixed head stamp cases (and they were MIXED) show a slightly smaller average group size and smaller std. dev., but the t-test shows that the null hypothesis (the data comes from the same set) is acceptable at the 95% fiduciary level.

Well, I'll be ..... Just when I thought I had an edge against the other IDPA guys in CDP class.
Even had a custom chamber gauge from Harbor Fraught tools. Guess I might as well ditch the Ronco 1 size fits all case trimmer with salad spinning attachment too...

I am 79 years old and have been loading my own 45ACP for just about 55 years.
Some of the cases I reloaded then were probably fifteen or twenty years old..
Never trimmed or measured a 45 ACP case. I do others but for some reason never 45's. Never had one split on me..
I did shoot many years ago Master class with those reloads...

OK, this topic needs to be retired.