Bushmaster Case Life

[GaCop]

How many loads are you getting from the Hornady brass? I have some that have been loaded 5 times and didn't seem to put and hold a decent crimp on my loads causing Extreme Spreads to be all over the place ). I tried annealing but velocity is still all over the place. The same loads were shooting low ES/SD in new and twice fired brass.

[07Kingpin]

Very interested in this.

[Hoot]

Though not a prediction of total life expectancy, I usually retire my cases after 5 loadings for the AR platform. Two reasons:

First, the sized cases shrink in length after each firing though the most occurs after the first firing. Once a case gets below 1.680 it is retired. The chamber is cut to headspace the cartridge at 1.70. If you've ever looked at what constitutes a solid NO-GO measurement, its a lot less than .020 inches. Luckily, at the pressures we use, the 450b is more forgiving than bottleneck calibers.

Second. This is particularly important if you like to load them at the top of the charts. The case head grows in diameter. The resizing die only goes down so far and in my chamber, once they grow more than .5017 in diameter, they get either stuck going in or coming out of the chamber. In this image, you can see the scuff ring where CHG is most problematic. That's just above where the web transitions to the case wall.



Notice the micro dots in the extraction groove? I add one every time I reload. Here'sThe Link to the article on how to make one of my "sproinkers" for applying the dots. They don't interfere with chambering and unless you eyes are goners, you can see them without magnification. I mention this because you really should anneal them after every 5th reloading to keep the neck area from hardening too much. They won't split like some bottleneck cartridges but it does impact how much of your taper (or FCD) crimp springs back.

Anyway, that's my philosophy on how many times I reload cases. If you've been feeding them a spicy diet, that can occur in as little as 4 or5 reloadings in terms of CHG. As far as length shrinkage goes, my experience has been that a repeated diet of lite loads causes them to shrink the most. I don't need a bolt action or single shot rifle since I'm pleased with my AR variant, so I can't comment on case life expectancy in them. I do recall one of our early bolt action adopters saying he has gotten as many as 20 cycles out of his brass from his re-barreled Mauser 450b rifle.

Hoot

[07Kingpin]

Good info Hoot, what modifications would you make for bolt actions? Obviously we have a little different set of parameters.

[Hoot]

Good info Hoot, what modifications would you make for bolt actions? Obviously we have a little different set of parameters.

No clue. Ask someone with a bolt action. We're allowed to hunt with AR's up here in Liberal-Ville, so no point in retiring my AR variant to go with a bolt action. Trust me, I already have too many guns and our comfortable shooting weather season is short.

Hoot

[GaCop]

My issue loading for a bolt action is the fired/sized case mouth area doesn't seem to hold the bullet or a decent crimp after 5 firings. Annealed brass didn't seem to help any.

[Hoot]

My issue loading for a bolt action is the fired/sized case mouth area doesn't seem to hold the bullet or a decent crimp after 5 firings. Annealed brass didn't seem to help any.

If you hadn't already mentioned it, I would have suggested annealing. Depending upon what method you use for tumbling, you may have byproducts of combustion built up in the neck area. that stuff can be somewhat slippery compared to shiny bare brass. I have the opposite problem because I wet tumble my precision bottleneck calibers. The copper bullets literally weld to the bare brass. Now I've taken to lubricating the inside of my necks before charging them. Back when I just vibratory tumbled them in walnut, there was enough byproduct left behind that I didn't have to lube them. Chasing precision calibers can often be ne step forward, two steps back. Anyway, that's about all I can think of regarding neck tension. I got a little more by shaving down a shell holder in my lathe about .050 to allow more insertion depth into my 450b sizing die. Shrinks the neck a little more. I have it well marked and keep it in my 450b die box, away from my other shell holders. Don't want that to be three steps back.

Admittedly, that is a "bandaid" not a solution.

Hoot