[lee n. field]

please.

Note the primers on the 3 .40 S&W cartidges on the left. Note the bulge around the primer strike. This is commercially loaded ammo, not reloads, so I doubt it's an overpressure situation. Everything I shoot through my CZ-100 does this.

I'm used to seeing spent primers like the 5 on the right.

What's causing this? Is it a something to be concerned about?

[telewinz]

Could be excessive headspace or the firing pin hole is too large and is not supporting the primer at discharge. Either way I'd send it back for repair.

[T.Stahl]

Do you know someone who shoots a Beretta 92? Their primers look similar. The primer bulges back into the large firing pin hole.

[bpisler]

My ruger P-95DC was doing this with any standard pressure ammo along with shallow firing pin strikes.While i did have any misfires i was disapointed and sold it to a friend after showing him the problem.

[coonan357]

looks like standard primer flow , don't forget a .40 is a higher presure firearm than some of the others shown. as long as the primers aren't backing out or peircing I wouldn't worry , I find alot like these in my buckets of range brass

[SDC]

Nothing to worry about; all it means is that your firing-pin hole has a large chamfer on it, so part of the primer backs into it under pressure.

[mgjohn]

Normal, the primer manufactures have went to a sightly softer metal in the primers. They flow more now than they used to. Some over the early striker fired guns were having trouble setting the primers off. I see this all the time. Pick up some military surplus 9mm ball and compare to US commerical in the same gun. You can see the diffrence.

[riddleofsteel]

Primer flow varies with the metal hardness of the cup. In some batches you see quite a bit of lfow in ohters very little. The size of the firing pin in relation to the firing pin hole has so bearing on it. Too tight a hole and dirt or even oil could make for light strikes. Too large and well, you are seeing the beginings of that already. If all the ammo of many different types are doing the same thing try some lighter loaded ammo and see what happens.

[MoNsTeR]

Ditto on the Beretta 92, mild primer cratering with any and all ammo.

[BHP9]

CZ guns are noted for this. My Cz75 did this and it was not the result of the firing pin hole or high pressure. It was the result of too light a mainspring not imparting enough force to the primer.

Try a heavier mainspring available from Wolf Springs and the problem will probably disappear. As an added bonus your guns ignition system will be a lot more relialbe when it comes to igniting hard cuped primers or reloads that may not have a primer seated all the way down.

[yesterdaysyouth]

looks like every primer that's ever went through my 9000s .....

it still goes bang, and not KB....

[lee n. field]

>Try a heavier mainspring available from Wolf Springs and the problem will probably disappear.

Wolff doesn't have anything for the CZ-100. Too new, I guess.

[RobW]

Seems to be a pressure thing. When I shoot .44 Mag factory loads in my Winchester 94, the primers are bulged. When I shoot my "Cowboy loads" the primer is flat.

As the .40 operates with quite high pressures I think the bulged primers are normal.