question about rifle case trimming and gauging

[savasyn]

As I mentioned in a few other question threads, I've recently starting reloading for rifle after having done pistol for a while. I have a couple of questions about the parts that are different from pistol.

1)Does it matter whether brass is trimmed before or after sizing? I had assumed that it should be done after sizing, but I've read a few things where people do it before and there are specific case holders for the trimmer I ordered (L.E. Wilson) depending on whether you are trimming fired or sized cases. I have sized a bunch of .223 brass and will trim it once the order I placed arrives(hopefully tomorrow.) Does full-length sizing change the length at all or just diameter?

2)I set up my sizing die using a Lyman case gauge. I got it to the point where the average case head would be right between the min and max marks on that gauge. I found out that that gauge is apparently at the minimum tolerances for .223 as it wouldn't accept about 1/3 of the case rims I tried in it. I checked a few on a friend's Dillon gauge and every one dropped right in. I just received my own Dillon gauge tonight and tested a bunch of the brass that I had sized. In the Dillon, they are mostly at the minimum line with about 1/3 right in the middle. With the Lyman gauge they are mostly right in the middle with about 1/3 at max length.

Seems that the Dillon gauge I have matches what I was seeing with my friend's(also a Dillon). Given that I'm currently not making precision ammo, just plinking and 3gun fodder, going with the Dillon gauge is the better bet. Perhaps if I ever pick up a .223 bolt gun, using the tighter Lyman gauge might be better for those cases. Both my ARs are chambered in 5.56 which, as I understand it, is headspaced ever so slightly longer than .223.

Any thoughts on all that? I'm definitely interested learning all I can so I can get my setup dialed in with the least amount of fussing.

Thanks!

[joelogic]

Trim after sizing. Pushing the shoulder back can cause the neck to grow.

When setting up the die with the case gauge you should be using the bottom reading. The rim should be between min and max. By case head do you mean rim or neck? Neck sticking out past gauge means trim.

[savasyn]

Thanks! I figured trimming needed to happen after sizing. Makes the most sense.

By case head, I mean rim. I had set up the rim to be between the min and max using my Lyman gauge, but with the Dillon gauge, all that brass now sits right at the min line. I'll be adjusting it back to between for the next batch.

[joelogic]

Well the gauge is just a guide. Size and trim a piece of brass and then chamber it in the gun you are going to be shooting it out of. That is the real test. Gauge works for most semi-autos.