Saturday, April 29, 2017

Glock Bulge Buster

Brass fired from Glocks frequently exhibits a bulge near the base which can cause problems later if the stuff isn't completely resized.

Roger's comment from the previous Glock post notes that:
When a case has a Glock bulge, it will commonly chamber almost all the way in, stopping a few thousandths of an inch before full chambering.
This can and does cause the barrel to fail to go up completely into battery,
This commonly causes misfires and off center (low) primer strikes because the case / barrel are not all the way up in full battery and alignment with the firing pin.

 Some resizers don't reach that far down the case, so Lee sells a kit called the Bulge Buster which consists of an elevated brass pusher and a small bin to catch the resized brass. You need the Lee final crimp die in your caliber with the internal bits removed for this.

Or if you have the die, remove the internals, put an improvised pusher made from an old steel .223 brass with an old 9mm steel brass on top,

 a small plastic tub with a 7/8" hole will catch the brass as it pops through the die.
This brass had already been decapped and sized so this operation addressed only the bulge. There was a great variation in bulge amount from one to the next with most brass passing through the die and staying above the smallest diameter. I did have one that seemed to have no bulge at all that came back out the bottom having encountered no resistance at all going up. 

I tested this batch in my barrel and found them all to drop fully down with no resistance. NOTE: This trick will NOT work on loaded cartridges. Drat! Remember to lube the cases before resizing.


Tony Tsquared said...

Good to know. I shoot a G37 and carry a G26. The only time I have ever experienced the Glock Bulge was with TulAmmo 9mm. But it was really Crap Brass Bulge that occurred during crimping. The TulAmmo brass is too soft to be reliably reloaded.

Anonymous said...

I've looking for something like this for a long time. Unfortunately, the product description at Midway USA says it is specifically not for 9mm. (because of the case taper???) Oh well, I still may make one up for 45ACP.

Thanks for the info.

Billll said...

The .40s have a slight taper, but I decap and "size" mine before running them through the bulge die. The taper remains but the bulge is gone. The 9mm has a much steeper taper so running the brass through the crimping die will probably only remove the bulge to the diameter of the cartridge base (.391"). I don't shoot 9mm so I haven't looked. Question: Is the smallest diameter in the 9mm final crimp die equal to the largest diameter of the brass or is the taper included in the die?

Best case the brass would be sized to the .394" maximum diameter of the brass at the point of the case bulge where the brass is supposed to be somewhat smaller.

One fellow on the Glock forums said he ground his decapping die back to remove the inlet bevel from the bottom of the die allowing the die to go further down on the brass and get the bulge. For .40s and .45s, this probably works. For 9s this would make the overall taper smaller.The SAAMI page says the outside taper goes back 1/2". Measuring a couple of pieces of 9mm brass, the inside part goes back .56 to .59" which suggests that any bulge would be below the tapered part. Pushing your decapping die .09" further down would make the top of the case .001" smaller. This makes the bullet go in a bit tighter but your final crimp should take everything back to spec.

On a related note, I shoot 9x18 Makarov and I make my brass by trimming 9x19 brass back 1mm. The powder die flares the cartridge mouth to accept the larger Russian bullet and the final crimp brings the case mouth to Makarov specs. This means that the first time this goes through my gun the bullets have a slight hourglass profile to them. Once fired though, the brass is factory spec Makarov. I color the backs of the brass red and warn my fellow shooters that the "9mm Luger" brass with the red tails is 1mm too short to work in their Berettas and wind up getting most of it back.