40 cal bulging at base

#1 · August 28, 2008, 4:32 pm

I am having trouble with 40 S&W bulging at base when I reload,

I have the resizing die set to full bottom and backed off,

I have the powder drop bell for a very slight bell.

I have tried reducing / eliminating the crimp as the bullet is snug but still get a slight bulge at the base, Just enough to allow my slide to close but not to fire on my baby eagle and S&W-M&P

I have measured my bullets and they are spec, 3 different brands of brass, I use Dillon case lube, (Great stuf and it dosent evaporate like the rcbs lube does)

Any ideas? Ihave been reloading for years but 40 is new to me, and I dont have to set up very often as I have 8 complete heads with power measures,,, (I did reload ~800 rounds 2 years ago and had a few maybe 20 with this problem and thought it was because the pistol was getting hot).

Thanks in advance

#2 · August 28, 2008, 5:23 pm

First, check by sizing about 20 cases, and see if they drop completely into the chamber, and freely fall out. It is normal to see a slight bulge where the base of the bullet stops. Is this bulde equal all the way around the case? If not, then loosen all of your die lock rings, and with a case or cartridge in each station pull the handle down, and with the cases/cartridges up in the die tighten the lock rings. this makes sure the dies are centered in the toolhead, so that the bullet is seated straight.

#3 · August 30, 2008, 2:09 pm

Checked fit after sizeing thy were ok.

the bulge looked uniform and measuring with calipers and rolling the brass in the jaws looks good,

Will try braking things loose with fresh brass in each station will lock in place,,,

will reply next week when I have time to rey this... thanks for the idea to try...

#4 · November 4, 2008, 9:37 pm

Slight bulging at the base after a full-length resize is completely normal for pistol brass. If it is abnormally bulged (where it will not chamber during live-fire), then there is something wrong with the sizing die.

#5 · November 13, 2008, 5:36 pm

I am a Dealer in Canada and have solved the buldging issue to the point that i no longer even need to chamber check my ammunition. remove the sizing die, grind the bottom lip off the die up to the carbide. this will allow the die to go slightly lower and remove the buldge found around the bottom. the die steel is not very hard and can be ground down very easily with a 5" or 6" bench grinder. The carbide is very hard as well as slightly tapered which still allows easy feeding of the brass into the die. I have loaded close to a million rounds on my 650 with complete sattisfaction.

#6 · November 11, 2009, 4:19 am

I am having the same problem. When I try to drop a resized case into the gauge it falls 90% in but the last 10% does not go into the gauge. This brass had only been fired in my SIG 229 that has the best case support on the market unlike the Glock. So what gives? I have read that people are altering the dillion die to allow full case resize like the Canadian. WTF???

#7 · November 11, 2009, 1:58 pm

Start by checking some brass that is sized only. If the sized cases freely chamber fully and fall out of the chamber, then the size die is not the issue. 40 S&W brass fired in an unsupported chamber often exhibits this problem.