Trimming Brass Before Resizing....???

n/a

In my thread about reloading rifle ammo on a Progressive press someone brought up a valid point about inconsistent lengths in the brass....and needing to trim the brass after it is resized. I was wondering if I trimmed the brass before resizing, would the length remain consistent enough to make loading on a progressive press feasible??? I'll probably be crimping these b/c they will be for use in semi-auto rifles...

Nononsense...JustC...Tailgunner...anyone?

dcs shooters

I would think there shouldn't be enough difference to matter.

JustC

I wouldn't think it would be dangerous or create a faulty load every now and then,..but it isn't the best for utmost accuracy.

I don't trim brass until after the first firing. I would rather have the cases formed to my chamber first as new brass is quite often wayyy undersized and needs to be blown out to consistent dimensions. THEN,..once the body and shoulder dimensions are uniform,...I'll trim to length.

garanch

Depending upon the intended purpose for the ammo. If you are just pumping out rounds to go plinking then it will not matter. But, if you need some very accurate ammo (for competition etc) then trimming each case to exact specs. is a must. If you do not believe me test it yourself. Find a batch of the same length cases and load them, then find a batch of different lenght cases and load them with the same components as the first batch. Shoot the two different batches for groups and see for yourself.

Case preparation , component exactness, and consistency are as important and a must for tight groups as any other factor (quality firearm) included.

garanch

I think I need to clarify my last post. I should have taken into consideration that you were loading on a progressive press. I would assume that since you are using a progressive then the ammo is not for competition (exactness). When I use the progressive, I do not trim after resizing, (because I am looking for mass production). I do Mic. all of the cases prior to beginning, but not after resizing (on the progressive).

With the single stage, all cases are measured and trimmed if needed after resizing (due to the fact that these are for extreme tolerences, competition, etc.)

jonk

Trimming before sizing with a trim die would work; otherwise the mandrel will be too loose in the case mouth. Just a thought.

n/a

quote:Originally posted by JustC
I wouldn't think it would be dangerous or create a faulty load every now and then,..but it isn't the best for utmost accuracy.

I don't trim brass until after the first firing. I would rather have the cases formed to my chamber first as new brass is quite often wayyy undersized and needs to be blown out to consistent dimensions. THEN,..once the body and shoulder dimensions are uniform,...I'll trim to length.


That's the way I do it with a single stage press. If you were reloading these for a semi-auto, would you just neck size them or would you full length resize them so that they feed better...or would it matter???

I'm just looking to stock pile some ammo here...I'm not trying to develop extremely accurate handloads.

n/a

quote:Originally posted by jonk
Trimming before sizing with a trim die would work; otherwise the mandrel will be too loose in the case mouth. Just a thought.


I've never used a trim die...how do they work?

bpost

A Dillon power case trimmer will trim and size if you have enough stations available to de-cap at another station.

jonk

A trim die is a hardened carbide (usually) die that allows the case to protrude through the top; essentially it is a short, hollow die. It goes in the reloading press. You then take a rasp file to the protruding case and file flush with the die. Supposedly the file doesn't damage the die, as it is notably harder than the file but I can't attest to this as I've never owned one as there are other easier options for trimming brass, but have seen pictures. It would be good perhaps for fairly radical case alterations like taking 10mm off of a 30-06 case when forming 7.65X53 Mauser for instance. That way you could take a dremel tool to the case, cut it off, then file flush. Of course, finish with a chamfer inside and out.

RCrosby

I usually trim before sizing, simply because the mandrel on my Forster trimmer won't fit in the neck of a sized case, at least not very easily.
It would be easy enough to measure the OAL of half a dozen cases before sizing, then again after sizing, to see how much difference there may or may not be with your brass and dies. After that initial firing, as mentioned above, I'm guessing the difference will be minimal. If there is enough difference to consistently measure, then you may want to compare results at the range between brass trimmed before and after sizing. Someday I may be good enough to tell a difference under those conditions, but I "ain't there yet".!
[:D]

JustC

Eric,..it depends on if you are going to re-use the cases once they are fired. If you are simply making some ammo to stockpile and not reload it,..then I would NK size. If you are going to reuse it,..I would FL size to keep it simple and make it usefull in multiple rifles. It doesn't really matter either way since you should set BOTH dies from the start and leave them set. This way you can neck size for best accuracy,..then when feeding becomes an issue you can bump the shoulder and get right back to it. I guess the more finicky method that could cause failure to feed in one rifle and not another would be the NK sizing method,..but for only one rifle,..then that is a mute point. or multiple rifles chambered the same,..I would stick to FL sizing and simply have a lot of brass on back-up to replace the ones that have casehead seperations. MHO

bobski

it may be ok to plink, but did anyone think to ask the chamber what he thinks? pumping bad reloads down the tube doesnt help bbl life.[;)]

Dumpster Baby

Since I reload mostly military calibers with bullets that have a cannelure, and my dies are roll crimp rather than taper crimp, I have to be very careful about trimming and crimper adjustment. I trim after resizing, and had to polish down my Forster trimmer pilots to fit the smaller case mouths. Trimming before sizing is easier, but introduces slight variances in case length that affect bullet crimping.

If you don't crimp bullets in you don't have to worry as much about case length, but you can't ignore it either.

RCrosby

It's the "slight differences" that Dumpster Baby mentions that fascinate me. Guess I'll have to do some before after measurements; maybe on Hornets, .222, .270 and see what I get. I expect there may be "slightly" more variation with looser chambers, but when I get around to it, I'll report back. Be interested in hearing anyone else's results with similar test.