Can someone explain Primer Wipe?

[Coltdriver]

I think that is the correct term.

When I shoot my Kahr 40 the primer has a slot as opposed to a dot.

Is this normal for a 40? Is the slide slammed back so quickly that the firing pin can not retract?

Thanks in advance for your answers.

 

[shooter22]

I am not familiar with the Kahr, but if it don't have a hammer, it probably has a striker system instead of a firing pin. My brother had a S&W sigma and it has a striker system. It is sort of like a 22 rimfire, only it strikes the primer either in center or near center.

Shooter22

 

[Chris Orndorff]

Primer smear is from the firing pin staying in contact with the primer as the case begins to be ejected. Quite normal in many pistols.

 

[Brasso]

I usually associate primer smear with high pressure cartridges like .357 or .44 mag. My definition is when the load is too hot and the primer begins to melt as the firing pin backs out and the primer gets smeared like cake icing.

 

[Joe Demko]

I had this occur with two autopistols, a TZ75 and a S&W 4566. In both cases, I replaced the recoil spring with a slightly heavier one and I replaced the firing pin return spring with a slightly heavier one in the Smith, as well. Presto, no more primer wipe. Was it necessary? No. Primer wipe is normal in many autopistols. If it bothers you anyway, as it did me, you can correct the situation pretty quickly. If the Kahr is striker fired, you don't have the option to replace a firing pin return spring, but replacing a recoil spring is as easy as field stripping. The idea is to use one just heavy enough to keep the slide locked a tiny bit longer. Don't get crazy with heavy springs, you don't want to compromise reliability or batter the pistol more than necessary.

 

[ctfrank]

It is just like Chris says. My MK9 does it. It is common with small, compact pistols in 9mm or above with a short slide and slide stroke

 

[leapfrog]

It is caused by the premature unlocking of the barrel from the slide. In my experience it occurs most frequently in 40 S&Ws. In fact, I've never had a 9MM or a 45 auto to do it regardless of slide length. My KelTec P11 in 9 MM doesn't do it, but my full size EAA Witness in 40 S&W does. All my pistols have extra power recoil and mag springs, but the 40 calibers are the only ones to demonstrate this problem.

 

[Chris Orndorff]

It is quite common/normal with Sig .45's. Haven't seen it with my Sig 9mms; can't comment on other guns/calibers.

 

[boing]

My K9 does it.

From the Owner's Manual:

Note Regarding Primer Indent:
Upon examining fired cases, you may notice that the primer indent appears distorted or stretched. This is normal for the striker system design of the Kahr K9.