Just getting into reloading. I have measured a bunch of 30/06 brass and all are under the max length but they vary about .003 between cases. Is there anything accuracy wise to gain by trimming them all down to the same length? I did have some RP brass that was less than the trim to length ~2.478. I sorted those out.


Thanks

As long as they're less than the maximum length, nothing will be gained by trimming off a few thousands of an inch in the accuracy department. Also, if a case is 0.005 in shorter than the published trim length, I would still use it; it's going to stretch when you shoot it anyway.

IT WILL AFFECT THE ACCURACY TO SOME DEgREE.
it defently will affect bullet grip which will play with the pressure curve. how much will depend on your loading method.
I try to keep all things equal. if you are going to crimp these reloads it is a must to have them all the same length.
if your just going to blast at rockchucks and no shootng for groups I dont think it will make much diffrence at all but always be aware of max length.
Dave

How important is squaring the case mouth?

Based on what I've experienced, it will make a difference. The issue/question is how much. I go through time consuming task w/ all my rifle loads but, I have to admit to being very found of small groups. I've taken Whelen's treatise that only accurate rifles are interesting to a higher level.
I square the case mouths, uniform the primer pockets, deburr the flash holes and now use a digital scale and try to load all of one load w/ the same lot of primers and powder. Then I check their concentricity and mark them accordingly. Is it necessary for hunting loads, not only no, but hell no. Does it produce very accurate, confidence inspiring loads, hell yes!

"they vary about .003 between cases. Is there anything accuracy wise to gain by trimming them all down to the same length?"

Variations of that degree won't matter, for any purpose. Three times that MIGHT matter ... a little.


"How important is squaring the case mouth?"

IMHO, obtaining "square" case mouths is vastly over-rated. Well, not allowing them to be out of square more than 30 degrees IS important. Since that much is impossible, it's hard to imagine that being out of square any real world tiny amount is basically irrelivant.

Consider this; upon firing the case expands and the forward portion slaps hard against the chamber walls, sealing and effectively becoming part of the chamber. Small variations in the case mouth will mean nothing to a bullet beginning it's brief journey out of the fully expanded neck in a sporting rifle.

In my book.....nothing of any meaning will be gained.

Wellllll, sooner or later you're gonna have to do it so's why not now. And start out with everything even and the case mouths square so the bullets seat nice and even and all that.
Pick your shortest case (even if its slightly shorter than the book sez it ought to be) and trim it just enough to square it up and trim the rest of your cases to match that one. Then chamfer and deburr and you're set to go.
Then if your accuracy sucks, you know that it's not because you cases are different lengths.
FYI, I do believe different case length does affect accuracy.

Thanks for the info. Since I'm only loading about 20 rds per batch trimming is not that big a deal anyway. My buddy who is helping me out uses the lee tool that has the cutter and stud with a drill attachment so you can only trim to one length. He says it works fine. The shorter cases I'll just sort out and load separately.

I have one of the rcbs elec trimpro lathe type trimmer....hardly ever use it anymore...that lee lock stud in a drill with the pre set trim length is as fast and cost effective a tool as you'll ever buy for reloading!!

If this is the first time they will be shot in your rifle....don't wast the time.

You can trim all cases to the same length, load them as carefully as possible (same powder lot, same load, same bullet etc etc) fire them all in the same chamber, and resize them all with the same die setting. After you are done with this, measure cases for OAL, and you'll likely find variance greater than .003".

Why is this?? I don't know. It seems that one of the few universal truths about reloading is that "brass varies".

Given the above, if you decide you will not tolerate an OAL variance of .003", then you have also decided you are willing to trim cases after every firing/sizing...

Is it going to make a difference?? Hard to say. If you are a top notch benchrester you might be able to tell the difference.

- mike

P.S. The choice of your trimming tool will also affect how low a variance you can obtain in OAL of trimmed cases. You'd be surprised how inaccurate many trimming tools are (at least if you pay attention to thousands...). One of the few tools I have run into that will allow you to keep variances (much) below .003" is the Wilson trimmer.

[QUOTE

Is it going to make a difference?? Hard to say. If you are a top notch benchrester you might be able to tell the difference.

- mike

QUOTE]

Onlyif you have a benchrest gun -- absolutely tight tolerances. That's when tiny details can matter. (Also being able to shoot so well you can notice the differences...)

I've gotten to where after I resize,I just go ahead and run it through my trimmer.It takes just about the same time to do it as it does to measure and it keeps all the brass the same length.

Lewis, as you can see, all of us have our own methods due to our personal preferences of what MIGHT be helpful. But none of us presume to shout that tiny variations in length OR absolute mouth squareness DOES mean a thing! Even to the BR crowd.

It's interesting, to me anyway, that some fairly significant variations in case shoulder length occur during FL sizing but I NEVER see any mention of that on the web! Anyone with a means of accurately measuring head-to-shoulder (RCBS Mic or Hornady LnL, etc) should check a single box of cases before and after FL sizing to see what I mean. That's MUCH more significant than any small case length/square questions but it's not even recognised?

Baldhunter makes a good point. With the lee tool you can probably cut 20 cases in the time it takes to measure them.