Bulge Buster
Hello. It's been a few years since I logged in, and I doubt any of you might remember me, apart from that prehistoric geezer ReloaderFred, if he is still around.
I came across the bulge buster kit in the March 2010 American Rifleman, and by some strange coincidence I DID have some bulged 357 SIG brass from my P226 while I was working up loads to the max levels listed in some of the reloading manuals. (125 gr. GD @ 1450 FPS)
To begin with, the area that is unsupported in a SIG barrel is far different than the feed ramp exposure in a Glock barrel, but it is still there. The picture below shows the exposed base of the case, and it is precisely this area that bulges out, and leaves a ring of just this height after it is full length resized. I am using a Dillon FL carbide die, as they were the only company to offer one when I bought the dies.
Now, how is this bulge forming? The answer seems fairly obvious, and it is that when shooting near max loads in the SIG barrel, the pressure from the case pushes down on the unsupported base and makes it bulge out. The general movement of the brass is shown below:
Now, the thing that worries me about this is where is this brass bulge going to go if you run the case through the factory crimp die in the normal (case mouth up) direction? It might be that swaging brass is swaging brass, and when you push the side in it will go back to where it came from. Considering the amount of force required to resize some of these bases, however, it might be the case that with the friction involved, the brass will get pulled further down and start to change the shape of the case bevel.
As such, what made sense to me when I saw the original ad for this product was that you would want to run the case through the die BASE UP to make the brass go back where it came from as much as possible.
To do this, I simply got a bolt of the appropriate sub .355" diameter, and used that to push the case upwards base first through the factory crimp die. I moved the crimp die up a bit in the press to maximize the leverage factor of the ram when pushing the case through, and the system seems to work quite well.
One final note: I have observed a substantial difference between Winchester brass and the Speer Lazy-S brass, with the ring on the Winchester brass being much sharper on the top edge. With the Speer brass, a discernable ring does not really form when it is full length resized, even though the case base is bulged just as much in some cases as the Winchester brass. If I had to guess, I would think this might have to do with the temper of the brass, but that's just a guess on my part.
This is the first time I have seen base bulges like this in cases, and I have never seen it in 9mm, 10mm, or 45 ACP before. I agree with the viewpoint that Lee carbide dies seem to resize the base better in these calibers than other dies (RCBS, to name one). For the record, I am mostly an ALL-STEEL 1911 and CZ clone guy in autoloaders, and have a distinct aversion to striker fired guns (i.e., Tupperware) where I cannot see a hammer and its firing position.
