Military brass is Stronger Brass. Yes, it is. Strong is good, we like strong.
You chamfer out the primer pocket crimp zone (most of it, anyway) and that leaves a tight assed little primer pocket. The primer OD constricts where it goes past the tight zone, and re-expands when the primer goes off to 100% fill the hourglass shape. The top of the primer expands to fill the chamfer taper from where you beveled out the primer crimp.
I have never had a milsurp case fail, but I have had commercial brass heads over-expand because the brass was soft (the native brass and the heat treat wasn't optimal).
MM can vouch that I always obey the reloading books and my loads are always mild with well rounded primer tops after firing the rounds.
hee hee Military brass is overbuilt on purpose as machine guns are HOT RUNNING suckers and rounds left in the chamber when you stop after firing for a bit can self-detonate from excess chamber heat and those cook off rounds are REALLY hot rounds when they cook off all at once like that ....
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Now, some new knowledge based on cubic boron nitride coated bullets and Reloader 19 powder.
Prep coat your completely clean bore with cubic boron nitride (alcohol and powder on a jag rag) then start working up from book max using a magnum primer. Mag primers are stronger cups and it takes more pressure to seat them, but they can take a lot more pressure and still give normal visuals on "load hotness".
You can cook up your own version of "light magnum" ammo
at visually reduced pressures by loading compressed book loads of a "too slow" powder like Reloader 19 -- upon firing it spits the bullet out quicker due to greatly reduced bore resistance friction and it does not develop excess visual pressure signs on the primer or on the head face as the bullet leaves sooner and the pressure curve is lower and it peaks way deeper inside the barrel compared to untreated bullets.
A really really big broad pressure curve, if adjusted back up to be just as high as before has a lot more area under the curve compared to normal stuff and it transfers a lot more energy to the bullet (yes, even the heavier ones) than you can get with an untreated bullet and bore.
Indeed, you can actually LOSE some 50-60 fps on normal book loads using cubic boron nitride coating on bullets and bore
if you don't counteract the effect somewhat. Common counteractions are using magnum primers and post-crimping the bullets to increase the shot start pressures.
Some crazy people use even more of a slower powder behind a heavy for the caliber bullet, but that seems just plumb crazy now doesn't it?
Moving those heavy slugs as fast (or faster) than dry untreated normal weight bullets at reduced or same pressure levels is just plain wrong, don't cha just know it?There is some visual pressure sign "slight of hand" going on here, I freely admit this very openly right now. Having a broader flatter pressure curve is relatively easier on the magnum primer, which was over-built for old abrupt maximum pressure loadings common in the 7mm and 30 caliber magnums.
So, like I have said, some Cheapie types
have put in a few extra grains of "bullet compressed at seating" slower than normal powder until they get some "appropriate" primer pressure signs back again. They get some extra bullet speed and some more kick at the shoulder, but that is just the price they pay to get those results.
Other old shooters simply appreciate not getting their shoulders kicked around so badly and tend just to leave it slacking. Clean up is much easier as fouling (copper and powder) won't stick around when a CBN coated bullet is fired down a CBN coated bore.
Accuracy is good, too.
Reloader 19 is well known already for heavy 180 grain bullets in the '06, but folks playing with cubic boron nitride are learning new uses for the clean burning stuff with both 180's and 150's when playing the new lite magnum game in 30-06.
An example from 7mm-08 land: apart from it kicking too hard for an old man to like, a light tapered 22" 7mm-08 can spit a 160 grain bullet out at 3,000 fps using Reloader 19 and CBN coated bullets.
(actually, it can do 3,100 fps but I simply can't stand the kick with that one plus it is getting some head rotation burnishing and extractor cut out edges showing up on the case head).
That's potent full powered 160 grain 7mm bear and elk medicine coming from a light 22" short action carry rifle.
New, Evolutionary stuff, this.