"Scratched" primers on spent cases

[Arizona Jake]

Hello!

While shooting my SIG p220 today, I noticed, as I was picking up my spent cases, that the primer indentation on the cases, instead of being the usual regular, round marks, had someting like a comet-tail on them. The marks were not deep and elongated, like those left by Glock pistols, but it they appeared as if the firing pin was prodruding into the primer while the case was being ejected, tailing off.

Is this caused by debris or by the firing pin hole getting full of crud? I sprayed the firing pin hole with brake cleaner while cleaning the pistol. I won't know if that will cure the problem. Has anyone run into this type of thing before? Any and all help is appreciated in advance.

Regards,

[wtroger]

Yep seen this before Firing pin is still up against the primer when the slide is starting to move back and down during the ejection phase of the firing cycle. More semi autos do this then most people realize.

[tacklebury]

Are these hotter reloads?  Might need a stronger recoil spring to respond to the increased power.  If not, dunno... 

[Frank46]

My sig 239 in 40 S&W will show exactly what you describe when shooting rem 180 grain factory ammo, however doesn't do it with winchester white box same bullet weight. My sig P6 in 9mm doesn't show this at all. I'm thinking the rem primer is softer than the win. Frank

[Arizona Jake]

Thank you all for the responses. I'll shoot a few more rounds this coming weekend with a completely clean pistol (except for some grease on the slide rails and other points of metal to metal contact).

I was using factory 230 gr. ball ammo and reloads consisting of 200 gr. LSWCs behind 6.5 grs. of Unique. Primers were Winchester large pistol. Let's see what happens next weekend.

Again,thank you all for your answers!

[gunnut69]

Likely just a weakening spring(recoil). Remember if going to a harder spring replacing the firing pin spring is usually a good idea.. I like the strongest spring that reliably cycles the gun and back up just a bit. This allows better cycling if a limper than normal wrist is encountered as in damage encurred in a fight.. The firing pin spring on the SIG is pretty small so watch for slam denting of primers.. Higher recoil impulses, heavier bullets and/or higher velocities will agravate the problem as will some calibers. Remember springs wear out and need replacement. Also a note, this can break firing pins if allowed to continue and worsen.