barefooter56 said:
CatShooter,
Question. I have heard that the LAPUA and NORMA cartridge cases have more zinc in them than Winchester , Remington, ETC. That is why they can be reloaded many more times than our domestic brass. The other factor that helps are the tight primer pockets , especially the LAPUA cartridge cases. Is the ratio of zinc to copper the key to good brass?
Thanks!
Phil Hoham Berger Bullet Tech
Phil...
I am not sure. My industrial manuals are still packed away, but this I remember - while standard cartridge brass is 70%/30% Copper-Zinc, the Zinc can vary, and less Zinc makes softer brass.
And our cases are made of industrial grade brass, which is not the same from batch to batch. It's not like a metallurgist in a white lab coat says, "We only have 29.7% Zinc - throw more Zinc in the mix."... it is more like some guy on work jeans says "It looks like maybe 27%, go with it!"
I think the European makes are more in line with the white lab coat process. If you look at the grain structure under a microscope of Lapua and US... it will really wake you up, and you will understand why Lapua, Norma, and RWS brass is twice+ the price of US brass.
One of the things to remember is that cartridge companies are making a disposable container that goes "Bang" once and is thrown away.. it is us munchkins that pick it up and reuse it.
So the limits of what they do, is based on what we will pay. If American reloaders (as a whole group)were willing to pay $1.50+ each, then the companies would compete for the business by making better cases - but, with the exception of some of us, most people use brass cases as they were intended - one use and lost in the woods.
That being said, I don't think you can make a firm statement about brass case alloys. The hardness in the head-web is more a result of how the case is formed... if you force the head by a hydraulic press, it will be very soft, whereas, if you hammer it with many blows, it will be hard... so it is process which is the key factor.
Back in the beginning of time (~1975) I bought a new 40XB Rangemaster in 22-250, and 400 pieces of Winchester brass.
I was annealing way back then, and I annealed those cases every few loadings - I neck sized them, and burned out the barrel on PD's.... I replaced the barrel, and the cases would just chamber tightly, and after the first firing, they fit fine, so I burned out the second barrel on PD's... and a third.
I burned out two more barrels, only having to FL the cases on the last two barrels, for the first firing.... I annealed the cases all those years.
About 4 or 5 years ago, I rebarreled that 40XB to .244 Rem 10-T, and packed the cases and dies away, cuz I took the 12 step pledge on the 22-250. No more... I mean, the 22-250 was boring
About 2 years ago, I fell off the wagon and picked up a yummy 700 VSF with less than 150 rounds through it.
But now, Lapua was making 22-250, so I threw out what what was left of the original 400 pcs - about 370-ish, cuz some were left in the grass.
The point being that those cases never failed from splits or pocket expansion. The loads I used were probably in the 50-55 Kpsia range. Heavy in those days, but kinda light by today's standards.
They had ~45 loading on them.