How much effect does pistol brass have on the re-load ?

[Riss]

Specifically something higher in pressure like the 9mm or 40 S&W ? Wondering how much it can change the pressures, mixed brass with different case wall thickness, already fired cases maybe stretched a little.

 

[strat81]

Depends on how close to max you are running.

If you are loading with max powder charges, shortest possible OAL, magnum primers, on a 100 degree day with ammo that sat in your trunk all afternoon, yes, brass can make a difference.

Thicker brass may decrease volume and thus increase pressures, but it *may* be stronger. Thinner brass may have more volume and thus lower pressures, but it *may* be weaker.

The chamber of gun can play a role too. Is it fully supported or not?

 

[Riss]

Using a new KKM barrel in a Glock. It is fully supported. Had really wild spread of velocities on a batch of mixed brass last week. Trying to get a stable load for IPSC. Need over 920 fps with my 185 gr Berry's clad pushed by 5.8 gr ? of Power Pistol. Sorted out 2 lots of brass for same headstamp from the barrel. Hope to get them Chrony'd tomorrow. I increased the powder charge about.2 gr since the last load, it only averaged 917 fps ant they were not consistent. I am hoping that I can figure out what the problem is.

 

[345 DeSoto]

If you're going to shoot IPSC, test the various headstamps and stick with one Mfgr. It just helps to eliminate one more of the variables in your ammunition...