Thread: Trimming brass

How often do you or do you need to trim brass and is there a way to reduce brass flow?
I know that certain cases with more taper are more prone to flow then others but it seems like I'm forever trimming my brass.

What brand brass mate? I dont trim bugger all but as you say cartridge dependant

look at partial length resizing...it might help. by not shrinking brass so much it has to enlarge less upon firing .

Brass is Hornady. 6.5 grendel so not a lot of taper.

Not familiar with the cartridge havent loaded for it , hornady can be pretty soft from memory id try different brass if its available

At a minimum, you should trim the brass whenever it exceeds the max allowable case length. It might take 1 firing, it might take 10. There's no set number. A case might even shrink on its first firing.

Modern cartridges with straighter walls, sharper shoulders, and tighter chambers, stretch less from firing and sizing. E.g. 22-250AI virtually doesn't stretch. Plain old 22-250 stretches lots in comparison. As does 270, 303 etc... Where it headspaces also matters.

Ive got a weird one. 3 6.5x55s the two military ones never seem to need trimming but using similar load in my t3 it always seems to need a trim. I use a lee hand case trimmer

With my 6.5x55 I would wait till one of the batch reached Max length and then trim them all. This was about 3-4 firings. Now instead of measuring all of them I trim them every firing.

If you want to reduce brass flow, don't anneal the cases.

Cheers for the help guys. Think last time I didn't trim back enough. Only a few though. Hopefully after next round they won't have grown much

There a number of factors in lengthening of brass when fired. First is how much the shoulder is set back when the case is sized. Neck sized cases seldom need trimming, the same with very light loads. With Full length sized cases and standard pressure loads it depends on how much you set the shoulder back. The more the shoulder is set back the more you will need to trim next time. If you FL size with the die down hard on the shell holder then you will likely need to trim more often. I have gone through how cases stretch when fired in earlier posts so won't repeat that other than it all happens in the chamber and it is just a matter of keeping free headspace to a minimum. Using a comparator to adjust your dies to set the shoulder back the bare minimum is the key. From there on measure each load and trim when close to max.
Regards Grandpamac.

The other thing is the trim too length values are to suit any and all. I have measured all my chambers using Sinclair's gauge and can run most of them longer than the published lengths. Wouldn't recommend this though unless you can measure likewise.
I have one case that I have never trimmed to length, my Swede Ackley. Flow is very very small mainly due to the 40 degree shoulder. Also, when I formed the cases they came up shorter than recommended. After 600 shots fired they haven't reached the trim stage yet. All I do is tidy the chamfer.

Have seen the effects of a rifle club member never trimming. Very high pressure due to the projectile being pinched when trying to exit the neck. He had absolutley no idea of the cause.