40 brass bulges a lot - why ?

M

Mike H

New member
The brass from the PT-99 I borrowed didn't bulge at all, to the visible eye at least, the brass/steel from my Mak bulges a little bit.

But the brass from the .40's I have shot, a Glock 23 (a bad example admittedly) and a Beretta Cougar bulged A LOT.

How much should brass bulge, how much can it bulge, and is it really such a good idea. Some of that stuff looked like the bubble a kid blows with chewing gum. A little surprising.

Mike H
 
Actually the brass should not expand at all. The problem is the gun manufacture is not giving the brass enough support in chamber. I have a few .40 calibers in 1911 guns that I used the brass who knows how many times and it as good as new still. I shoot some pretty stiff IPSC loads through them too, and never have the slightest bulge. There is no reason for the condition other than trying to get the gun to feed easier. It can go Kboom to easy. Make sure you wear good safety glasses.
 
The cases fired in my Federal Arms 40 bbl do not bulge at all. These include the ones loaded to 1200 fps with 155 gr bullets.

Cases bulge because of too much pressure for the amount of support given the case. Some cases are better in this regard than others.
 
In my guns,which are properly built, I have no problems with any of the major manufactures brass. Personally I wouldn't feel safe shooting a gun that does that to the brass. Accident waiting to happen.
 
Also, remember that a load combination that is perfectly within limits and safe in one firearm might be a dangerous combination in another. As an example, consider this: You might fire one load that works to perfection in your SW 4006. Then, perhaps you happen across a EAA Witness pistol in .40 that is a great bargain. You don't realize that: a) the chamber is just a hair tighter; b) the barrel has a shorter leade; c) the firing pin strike is harder, etc. What happens? You will probably get higher pressure indications than you did with your 4006.

Bottom line? Work up loads for each and every individual firearm, even handguns in the same caliber. Avoid maximum loads; sure, you COULD blow that 300 grain LSWC out of your 5 1/2 inch .45 Colt Ruger Vaquero at 1400 fps---but why? (I acknowledge that this velocity is probably a bit overdoing it, by the way)

Use reasonable loads and medium bullet weights. Your cases--and guns--will last a lot longer.
 
Never noticed any bulging brass after shooting it out of my PT100. I have heard that it is unwise to load federal brass due to the casing wall being too thin. Can someone correct me if Im misinformed.
 
Tolerances Again

Hi, guys,

It is nearly impossible, not to mention expensive, to make any mechanical product to an exact dimension. All firearms and ammunition are made with tolerances set by some standards organization. For the .40 cal, which is a straight case, there is a chamber diameter with some +/- dimensions. There is also a cartridge diameter with +/- dimensions. The cartridge max diameter must always be less than the chamber minimum or some cartridges would not fit.

But if a cartridge made to minimum spec is put in a max chamber, the brass may bulge when fired. This will seldom present a danger (unless specs have been exceeded) but may cause case splitting if the brass is worked several times in reloading.

The chamber tolerances allow a reamer to be made to the max size and then sharpened several times before it becomes too small. High priced brands often use smaller reamers to start so their chambers are tighter than those of companies which try to get maximum use of their tooling.

Another brand or lot of ammo also may work better.

Note that this is not about case expansion due to an unsupported case head. That is another issue entirely and is a question of either the design of the firearm or the modifications that might have been done on it.

Jim
 
Its from the unsupported chamber of the glock,I think thats why they dont want you using reloads in the gun. Some brass is weaker than others, are you shooting reloads? My glock reloads are pretty mild and I wont reload certain kind of brass becouse of this problem.
 
Last edited:
Seems that Glocks have always had a problem with bulging brass. Reloads made from Glock fired brass sometimes look like little belted magnum cartridges.
 
FACTUAL INFORMATION

The bulge will depend on the specific chamber of the gun in question.

Fedral brass is fine, based on specific chamber of the gun in question.

Many guns are big-chambered for reliability, so perhaps we notice more bulging.

I have two 9x19 barrels; one is so tightly chambered that some loads require NO resizing, while in the other barrel a 40 S&W round almost fits LOL. Think I get 'bulges' from it?
 
There always seems to be issues with the 40 S&W. I know many people own guns in this caliber, and have fired 1000's of rounds OK, etc., but I shied away from it since there is this constant thing of how far the bullet is in the cartridge, overpressure, chamber support, and so on. When I bought my HK I was originally looking at a 40 Glock. I went with a USP 45 instead. It wasn't worth the few extra rounds in the clip to have to worry about the thing going off in my hand like a Claymore.:eek:
 
53kidao, i'm right there with you. there's something to this, you never hear of many 9mm's going kablooey. maybye the germans were ahead of their time in designing a cartridge that is made for functionality.
 
Last edited:
It is not limited to .40 caliber. I have seen it in 9.mm and .45 also. We're talking unsupported case heads where the bulge is at the base of the brass. Either the manufacture of the gun or in some cases the owners of the guns take to much out of barrel throat area to make for easier feeding instead of building them to function properly without exposing to much case. It can happen with any caliber and one Company seems to do this with most of their guns.
 
Last edited:
Irock:

You are correct sir. The issue is with one certain brand of .40 even factory loads KB. This is the reason I sold mine. I refuse to live in constant fear of my handgun KBing.
 
You must log in or register to reply here.
Back
Top