Case Trimming

[sendero72]

Rookie question! Do you trim the case after each firing regardless if you going to FL or neck size or just stay within min and max case length?

 

[Lefty7mmstw]

Rookie question! Do you trim the case after each firing regardless if you going to FL or neck size or just stay within min and max case length?

I used to not bother, but I've read on trimming a bit, and I've gone to trimming on every firing lately. I can watch my growth better and set my dies up as I go if something is wonky. I've got most cal's I load down to .003" or less growth fl sized per firing. You will get more uniform case lengths if you do this. I don't bother to turn necks or weigh brass but trim every shot and uniform pockets, go figure.....

 

[justgoto]

I use the lee hand trimmer, so I trim every time. I waited once until the cases got to over max length and it was a chore to trim them all.
When I trim each time; usually there is such a miniscule amount of growth, that it takes seconds to trim to minimum length.

 

[sendero72]

Thanks for the replies guys! I shall trim after each firing!!

 

[Mikecr]

You don't need to trim -unless you need to.
NS'd only cases should never need it beyond initial preps, as they aren't changing after fireforming -until you FL size.

Timming is something people do alot of, because it's easy. They fixate on 'book max', because that's easy(but wrong). They FL size, because they think it's easy, yet it directly leads to a bunch of trimming(and other issues).

 

[Lefty7mmstw]

You don't need to trim -unless you need to.
NS'd only cases should never need it beyond initial preps, as they aren't changing after fireforming -until you FL size.

Timming is something people do alot of, because it's easy. They fixate on 'book max', because that's easy(but wrong). They FL size, because they think it's easy, yet it directly leads to a bunch of trimming(and other issues).

I don't punch paper with my rifles other than putting around and sighting in, load development, etc. I hunt with them, so I want absolute reliability and I do not care if I loose a reload or three from my rounds as a consequence. I'd rather trim and have the other "issues". I don't even own a neck sizing die. I trim .010" under and keep them there.

 

[sendero72]

These cases are for my 7 mag. Min case trim is 2.490 and Max is 2.500. Generally the case will stretch .002 per firing. I was thinking that once I reach 2.495 I would keep them trimmed at that length just to have more neck to grip the bullet. Does that make any sense?

 

[justgoto]

These cases are for my 7 mag. Min case trim is 2.490 and Max is 2.500. Generally the case will stretch .002 per firing. I was thinking that once I reach 2.495 I would keep them trimmed at that length just to have more neck to grip the bullet. Does that make any sense?

I trim to first insure smooth operation, and second to insure uniformity.

 

[Lefty7mmstw]

These cases are for my 7 mag. Min case trim is 2.490 and Max is 2.500. Generally the case will stretch .002 per firing. I was thinking that once I reach 2.495 I would keep them trimmed at that length just to have more neck to grip the bullet. Does that make any sense?

Every second firing works also, but watch your variation between casings. Sometimes it will be a couple thousandths by two or three firings in the longer rounds. The bullet is gripped by the total surface area of the neck, so it you have varying length, you have varying grip.

 

[sendero72]

Thanks again. This is the most accurate rifle I've ever shot and I would like to get the most out of it. It's shoots .2's or less everyday. .466@300, 2"@820, and 6"@1100yds and I'm somewhat new to the long range game and I need to get the most out of it and practise a lot. My goal is to break the 1000 yd mark on a whitetail this season. I shoot the 162 A-max. Has a Hart 26", 9 twist, #6 contour topped with a 8-32x56 Nightforce. My new MOAR Nightforce arrives tomorrow! Will sell the older Nightforce.

 

[jtkratzer]

My rifle loves a little roll crimp on the SSTs, so I trim my .260 cases to 2.025 and keep them there for uniformity on the crimp and length.

 

[Joe King]

I trim cases one time when their new and that's only to get the case mouth square and the same length as the others that I'm prepping at that time, so that when I debur the flash hole, and chamfer the case mouth their all the same all the same. I've never saw a reason to otherwise, I suppose if the case got long enough to reach the end of the neck portion of the chamber I would then also but then I'd just every case I have for that rifle and set em all back some distance for clearance, say for example 0.010" or what ever my lee trimmer sets them at.

 

[Clark]

I did a large scale experiment on trimming with a handful of dies and a handful of rifles.
Each population of brass was kept to one die.
I measured the case growth and trimmed with an RCBS 3 way in the vertical mill.

The lessons I learned are close to common knowledge.
The best way to trim is to not trim.
The best way to not trim is to keep brass dedicated to one rifle and either neck size, partial fl size, or push the shoulder back .001" with a FL die.

I could do 25 firings of 223 at 66kpsi by using a Lee Collet die, without trimming.

 

[boomtube]

" I would keep them trimmed at that length just to have more neck to grip the bullet. Does that make any sense? "

There's nothing 'wrong' about doing that but normal variations of the necks in individual case will have a much bigger effect on grip than a few thou of length.