Case trimming question

[EOD Rob]

I have a buddy that just bought a new rifle and got 100 pieces of mixed headstamp once fired brass with it. Of course, he wants to get to working up a load for it and I told him I'll help out. I'm prepping the brass and started to notice that a lot of the brass was not even to recommended trim length. I have never ran into this problem because I separate my brass at new. However, this is all the brass he has. So, my question is, should I trim only the ones needed to make the recommended length or should I trim to the shortest case length?
Please dont start with the "Just go out and buy new Peterson/Lapua brass and be done with it". I already know that answer, because thats what I would do. Just trying to help out a buddy.

Rob

 

[Bc'z]

I'd sort by head stamp, size, then trim all to same length.

 

[EOD Rob]

I'd sort by head stamp, size, then trim all to same length.

So, you would trim each head stamp to the same length separately? That should give us enough of each to get at least a few five shot groups per head stamp. Then he can work on getting new brass.

 

[EOD Rob]

So, you would trim each head stamp to the same length separately? That should give us enough of each to get at least a few five shot groups per head stamp. Then he can work on getting new brass.

Hornady seem to be the big offender here!

 

[243winxb]

Look at https://saami.org/standards for case minimum length.

 

[Bc'z]

So, you would trim each head stamp to the same length separately? That should give us enough of each to get at least a few five shot groups per head stamp. Then he can work on getting new brass.

Yes, and keep them batched.

 

[EOD Rob]

Yes, and keep them batched.

Thanks!!!!

 

[Webster]

I have a buddy that just bought a new rifle and got 100 pieces of mixed headstamp once fired brass with it. Of course, he wants to get to working up a load for it and I told him I'll help out. I'm prepping the brass and started to notice that a lot of the brass was not even to recommended trim length. I have never ran into this problem because I separate my brass at new. However, this is all the brass he has. So, my question is, should I trim only the ones needed to make the recommended length or should I trim to the shortest case length?
Please dont start with the "Just go out and buy new Peterson/Lapua brass and be done with it". I already know that answer, because thats what I would do. Just trying to help out a buddy.

Rob

It wouldn't hurt to trim to the recommended length in a reload manual. I assume it's a factory rifle and not for BR. I don't like the idea of trimming to the shortest. They will all grow a little in length with repeated firing. If they are all different length you shouldn't see a differnce on a target. Some people seem to be worried that a long case the neck will hit the 90 degree cut at the end of the chamber. If you look at the chamber drawings you have about 0.025" to 0.035" clearance.

 

[hoz53]

I have a buddy that just bought a new rifle and got 100 pieces of mixed headstamp once fired brass with it. Of course, he wants to get to working up a load for it and I told him I'll help out. I'm prepping the brass and started to notice that a lot of the brass was not even to recommended trim length. I have never ran into this problem because I separate my brass at new. However, this is all the brass he has. So, my question is, should I trim only the ones needed to make the recommended length or should I trim to the shortest case length?
Please dont start with the "Just go out and buy new Peterson/Lapua brass and be done with it". I already know that answer, because thats what I would do. Just trying to help out a buddy.

Rob

id be more concerned about case capacity than case length. ive had brass that was shorter than recommended trim to length alot of times. i wouldnt trim any to less than recommended trim to length unless i checked brass length with a bore scope. if he wants as accurate loads as he can get he should separate according to head stamp. if he just wants some blasting ammo trim the long ones to recommended length, start with a minimum load, load them all up and have at it.

 

[Chubbs]

id be more concerned about case capacity than case length. ive had brass that was shorter than recommended trim to length alot of times. i wouldnt trim any to less than recommended trim to length unless i checked brass length with a bore scope. if he wants as accurate loads as he can get he should separate according to head stamp. if he just wants some blasting ammo trim the long ones to recommended length, start with a minimum load, load them all up and have at it.

I second that. The case capacity can be the difference between a safe and dangerous load using the same amount of powder. I would check the volume of each different headstamp case using some water and Isopropanol. Plug the case with a spent primer and weigh the difference between the empty and full case. You may be surprised at the difference.

 

[EOD Rob]

All great and welcome advice! Webster, I'm with you on not liking to trim to case mini. There were three different head stamps Win, Fed, and Hornady. Hornady was the only one below manual spec. I trimmed the Win and Fed to spec, then found the shortest Hornady and trim all hornady to that. Hornady was all over the place.

 

[hoz53]

I second that. The case capacity can be the difference between a safe and dangerous load using the same amount of powder. I would check the volume of each different headstamp case using some water and Isopropanol. Plug the case with a spent primer and weigh the difference between the empty and full case. You may be surprised at the difference.

yup the capacity of those cases could vary alot. if he doesnt wanna go through checking with water ect he can just start with starting loads and work up.

 

[Webster]

I have a buddy that just bought a new rifle and got 100 pieces of mixed headstamp once fired brass with it. Of course, he wants to get to working up a load for it and I told him I'll help out. I'm prepping the brass and started to notice that a lot of the brass was not even to recommended trim length. I have never ran into this problem because I separate my brass at new. However, this is all the brass he has. So, my question is, should I trim only the ones needed to make the recommended length or should I trim to the shortest case length?
Please dont start with the "Just go out and buy new Peterson/Lapua brass and be done with it". I already know that answer, because thats what I would do. Just trying to help out a buddy.

Rob

Your post didn't indicate the caliber and what the rifle will be used for. If it's for plinking or short range deer hunting I wouldn't worry about case length or capacity. Just keep the powder charge mild. Go for accuracy. See if all the brands shoot to the same i point of impact with the same load.

 

[EOD Rob]

For the group, Webster and I already covered this in a PM. The rifle is a Tikka T3, Bartlien Barrel in 300WM, 1 in 9, 30". Pretty expensive PRS/Long Range Gun. As the description of the use and caliber, you can most likely tell that he is just getting into the sport. Not necessarily the caliber I would choose for PRS. Might be a little of my fault. I showed him my NRS 300 WM I used yrs ago and he went hog wild.
I did speak with him about the brass issue and that it might be a good idea to buy virgin brass and not use range or factory ammo brass. I'm sure he is just trying to save money since he just spent 3 paychecks on the rifle.

 

[Ned Ludd]

Trim where possible to the recommended case length. The shorter cases should grow in length with firing/re-sizing and will eventually be long enough to trim recommended case length.

 

[KY_Windage]

How accurate do you want to be? If you want good accuracy, then the first thing you need to do is to set your shoulders back about .003" from where the brass fired in the rifle come out. You need the Hornady Case Comparator tool for that.

Then you need to trim any necks that are too long. Ideal for this job is a $28 Wilson Case Gauge. Through experimentation you learn just how far a case neck can be sticking out of the case gauge before the bolt starts to get hard to close. Then you trim any that are at or past that dimension.

But don't trim off any more than you need to achieve an easy bolt close, because excessive trimming can cause neck-tension and/or runout problems.

Trimming to COA spec is okay, but not as good as the above. Trimming too much is nice in that you can go longer w/o trimming again, but you may pay a price in accuracy.

 

[Richard Coody]

Whatever works for you.

I don't do much trimming. Like my necks long. When I do trim I only trim half way between max and min. I trim the whole group of cases at the same time to the same length. Some cases (especially those with 40 degree shoulders) I never trim for the life of the case..

One thing I do recommend is don't trim new cases. Wait till they are fireformed. If you do trim new cases to min my bet is after fireforming they are short.

 

[cw308]

I would sort the brass by brand , different brands of brass could be thicker changing the inside volume, as far as trim length stay with the trim length listed the shorter brass leave as is just chamfer , most likely they will lengthen after a few reloads . Looking for that right load usually doesn't happen from the first reloads , in the beginning a few thousands shorter won't matter . Hopefully you are capable of shooting that 5 shot one hole group , then exact case prep is important . Just be realistic and concentrate on shooting form , don't go down that rabbit hole where shooting gets frustrating.
Chris

 

[EOD Rob]

Again, all great and welcome advice! Thank you all for your feed back!

 

[cw308]

What I forgot to mention , sometimes after firing your cases may shorten from expansion , but will lengthen when sized so set your die long and bring them down until you hit the case headspace your looking for .003 max. for semi and .002 for bolt.