Trimming brass?

[encoreguy]

I have heard many opinions on when and how to trim brass. I read the article on here and did a search on the topic. I read where you should shoot it first then trim to the shortest, I have read that you size new brass, then trim to the shortest case you have. What are your opinions?

I have a Wilson trimmer and am using Winchester brass currently for .243, .223 and 7-08.

 

[Bravo 4]

I use the chamber length gauge- insert into the case mouth like a bullet insert case into chamber, close bolt and extract, then measure. I do it several times to double/triple check and then trim my cases a few thou from the measurement. Ever firearm's chamber is gonna be different a little, so I don't just go off the manuals.

 

[Varmint Hunter]

I have always used the reloading manuals for the "trim to" length which is normally .010" shorter than the listed maximum length.

If I am match prepping cases I prefer to fireform them to my actual chamber before uniformly trimming the cases.

I would never trim to the shortest case length unless that is longer than the suggested "trim to" length. If the shortest case is excessively short; why ruin the rest of your brass to match it?

In non match rifles I have found no tangible benefit to trimming cases at all, at least not for uniformity. However, cases must be trimmed (at some point) to avoiding excessive neck length which could eventually lead to dangerously high pressure.

 

[MagnumManiac]

I have always used the reloading manuals for the "trim to" length which is normally .010" shorter than the listed maximum length.

If I am match prepping cases I prefer to fireform them to my actual chamber before uniformly trimming the cases.

I would never trim to the shortest case length unless that is longer than the suggested "trim to" length. If the shortest case is excessively short; why ruin the rest of your brass to match it?

In non match rifles I have found no tangible benefit to trimming cases at all, at least not for uniformity. However, cases must be trimmed (at some point) to avoiding excessive neck length which could eventually lead to dangerously high pressure.

varmintHunter,
I understand your reasoning for saying that if the shortest case in a batch is shorter than the 'trim to length', why ruin the rest by trimming them all to match that one.
The major reason for doing so is uniformity among case length.Not all cases in a batch of brass is going to stretch at the same rate,especially if you are working up loads with that batch.
A few thou' shorter than the 'trim to length' is neither here nor there in the aspect of functionability of your firearm,the brass will normally shorten on the 1st firing anyway,as you stated above,it may be best to fire them in YOUR rifle 1st before trimming for the 1st time.
I personally don't bother with this even though I understand the reasons for doing so.
I trim ALL my new brass to the shortest case in that batch,which is normally no more than a few thou' under the 'trim to length'.
MORE importantly is cases that are too long from new,I have come across this more and more of late.I think that ammo company's are becoming slack in this regard,trying to save a few bucks.
I also don't understand your statement about 'no tangible benefit from trimming brass in non-match rifles,not for uniformity'.
ALL brass should have a square,clean mouth for loading purposes,whether it is for a match rifle or not.It makes sense,to start out a bullet squarely into the case,the case mouth must be square,and chamfered to accept the bullet.
MagnumManiac
gun)

 

[anachronism]

I use a Gracey trimmer, with a Giraud carbide blade. I always size my brass first, tumble it, then trim it. for production rifles I cut the cases to about 1/2 the measurement between the maximum & trim to lengths. Match cases are trimmed to a thou or so below maximum length, just to give me the longest neck measurement possible, and to clean the case mouth before each firing. If i had to do this by hand, I would do it differently. My methods are for consistencys sake more than anything.

 

[Varmint Hunter]

varmintHunter,

I also don't understand your statement about 'no tangible benefit from trimming brass in non-match rifles,not for uniformity'.
ALL brass should have a square,clean mouth for loading purposes,whether it is for a match rifle or not.It makes sense,to start out a bullet squarely into the case,the case mouth must be square,and chamfered to accept the bullet.
MagnumManiac
gun)

I have made direct comparisons with brass right-out-of-the-box and brass that was trimmed, chamfered & deburred when being fired from factory rifles. Any potential benefit to trimming the brass was lost in the accuracy/inaccuracy of a factory rifle. Trimming brass for uniformity just does not make a measurable difference in group size in these guns.

 

[MagnumManiac]

I have made direct comparisons with brass right-out-of-the-box and brass that was trimmed, chamfered & deburred when being fired from factory rifles. Any potential benefit to trimming the brass was lost in the accuracy/inaccuracy of a factory rifle. Trimming brass for uniformity just does not make a measurable difference in group size in these guns.

Varmint Hunter,
I don't think anybody has ever stated that trimming brass effects group size,this is the first I've heard it mentioned.But,I've heard that long brass can influence group size by changing pressures.Especially if you have cases that differ in length,you will get different barrel times with different pressures.
I think the point your missing is ,even if trimming,chamfering and de burring don't change group sizes in factory rifles,at least your handloads and your brass are going to be CONSISTANT from shot to shot,which,hopefully,will give the best possible accuracy in your rifle.
The other reason for doing all this work for factory rifles is that when you seat a bullet into a case that hasn't been chamfered ,the uneven neck will shave material off the bullet which will unbalance it making it inaccurate.
This is not something that I compromise on.
MagnumManiac
gun)

 

[Moman]

I trim all cases to minimum, new from the box, and everytime I resize. I think it can make a difference in hunting rifles as well. Years ago, I only trimmed to minimum when they reached the max length. It was suggested to me by a friend to try this. I did, and it did tighten groups. Consistency is key!