Differences in Brass Weight.

02 September 2002, 13:18

Mauser98

I was loading for my .300 Win Mag this afternoon and out of curiosity, I weighed 5 each of two different brands of uncleaned brass. The first was Remington unplated and the second was Winchester chrome plated.

The weights for the Remington was 251.8, 249.3, 250.0, 249.7, 250.1 for an average of 250.2 grs

The weights for the W-W was 240.0, 243.4, 242.6, 242.6, 241.0 for an average of 241.9 grs.

It seems to me that a difference of 8.3 grs is significant.

My question is, how does this difference in weight impact pressures, brass life, velocities, etc?

Also, is there any downside to reloading the chromed brass?

02 September 2002, 13:54

<Don Martin29>

On the Remington .375 H&H cases that I have been using to make .300 H&H's the web of the case is thicker than WW brass. You can see the extra metal in new brass inside the case. The Rem cases last a little longer before the web gets too thin with the same load.

02 September 2002, 15:11

Bigdaddytacp

quote:
Originally posted by Mauser98:
I was loading for my .300 Win Mag this afternoon and out of curiosity, I weighed 5 each of two different brands of uncleaned brass. The first was Remington unplated and the second was Winchester chrome plated.

The weights for the Remington was 251.8, 249.3, 250.0, 249.7, 250.1 for an average of 250.2 grs

The weights for the W-W was 240.0, 243.4, 242.6, 242.6, 241.0 for an average of 241.9 grs.

It seems to me that a difference of 8.3 grs is significant.

My question is, how does this difference in weight impact pressures, brass life, velocities, etc?

Also, is there any downside to reloading the chromed brass?

GENERALLY the heavier brass will have less internal space and thus the same amount/weight of powder will cause higher pressure and usually higher velocity from the heavier cases.....this will cause different impact points to various degrees at longer?ranges........this is also why you need to keep the brass seperated by brand and lot to avoid problems with pressure with upper level loads and for varmint/accuracy/longrange type cartridges...as to nickeled brass....it seems to scratch the dies easier and some of it is more brittle than uncoated brass.....good luck and good shooting!!!

02 September 2002, 15:43

<David>

The Quickload program I have lists Win, Rem, Fed, and Norma cases individually for 300 Win Mag and different case volumes for each brand. This is about the only cartrige they do this for, so I don't know how representative these differences are in other calibers. All are listed in grains of water at the overflow point. Rem is the smallest at 89.5, next is Fed at 92.0, Win at 93.8, and Norma at 95.5.

If I take an identical load of 75.0gr of H4831sc with a 185gr Lapua Scenar bullet in each of the 4 different brands of cases and let Quickload predicted pressures, the results look like this: Norma - 50259, Win - 52483, Fed - 55079, and Rem - 59179, all in PSI (not CUP). The max pressure listed for 300 Win Mag is 62366 psi.

If I run the same test using a load that predicts a near max load of 62225 psi in a Norma case and use the exact same load in a Rem case the pressure jumps to 74829 psi. So as the pressures go up, the difference in the effect of case volume is even more pronounced.

The first time I made this comparison with Quickload, I was suprised to see that just by changing brands of brass can result in nearly a 9000 psi pressure change. I expected a difference, but not that much.

02 September 2002, 16:03

<MontanaMarine>

Here are weights of different 30-06 cases I have on hand, including a spent primer.

Norma: 183 gr
IMI: 198 gr
Rem: 200 gr

Loading the Norma brass, I can easily put 63 gr of RL-22. 60-61 is about all for Rem brass.

MM