Most likely cause of slamfire

[bbbean]

Yesterday, I was testing a new load in my Limited gun (SV/Caspian 2011) and had a mag that went to slidelock prematurely. I checked the chamber, dropped the slide release, and had my first-ever slam fire. Fortunately, the gun was pointed downrange, and there were no ladies present, so no one was damaged by the stray round or foul language.

Now I'm trying to figure out what the most likely cause of the malfunction was. I am 99.99% certain my finger was outside the trigger guard, and I've double checked for any sign of hammer follow just in case it wasn't. Last year, the same gun did fail to feed once with a stuck firing pin, but a thorough cleaning of the pin and pin channel fixed that problem. I have also found high primers before, but not with my current setup or primers.

I've done a much more thorough cleaning of the firing pin, replaced the firing pin spring, and blown out the firing pin tube with compressed air. I've also developed a renewed commitment to checking for high primers when I put them in the box. This morning I put another 100 rounds through the gun without incident.

Anything else I should check? In your experience, which is the most likely culprit - pin, primer, finger, or something else?

Edited July 19, 2010 by bbbean

[Corey]

primer seated too far out of the case? usually will do the trick and slam fire if its out too far and the pin makes enough contact.

[CSEMARTIN]

How much pretravel do you have. How much does the trigger weigh? I don't mean trigger pull. I mean, how much does the trigger physically weigh?

[bbbean]

How much pretravel do you have. How much does the trigger weigh? I don't mean trigger pull. I mean, how much does the trigger physically weigh?

It's an SV med flat trigger - light, with very limited pre-travel. If I had a trigger issue, though, wouldn't it have shown up before now? I've got 8-10K rounds through the gun.

[Pat Miles]

Did the hammer drop and cause the AD or was it a true slam fire? Obviously each cause will have you looking at completely different possibilities. Which one was it?

CYa,

Pat

[kamikaze1a]

The sear spring could weaken and cause doubling...maybe it's the start of things to come?

[bbbean]

Did the hammer drop and cause the AD or was it a true slam fire?

I don't know. Since the round cycled the slide, the hammer was back by the time I was in diagnostic mode.

[Guy Neill]

A heavy firing pin with a weak firing pin spring can also contribute to such problems.

Guy

[CSEMARTIN]

It's an SV med flat trigger - light, with very limited pre-travel. If I had a trigger issue, though, wouldn't it have shown up before now? I've got 8-10K rounds through the gun.

The trigger is fine. I think it's time to change your sear spring and probably your firing pin spring. As long as you have 10 thousandths pretravel, you should be fine.

Out of curiosity, do you have a habit of dropping the slide on an empty chamber? And, what weight mainspring do you have in the gun? Having this issue pop up after so many rounds, makes me thing something has worn out.

I love the 1911's, but they sure can be a pain in the azz sometimes.

[bbbean]

Having this issue pop up after so many rounds, makes me thing something has worn out.

I appreciate the suggestions.

FWIW, though, I don't think I'll consider it an "issue" until it happens more than once. I was just checking to see if there were any obvious things to check I hadn't considered. At the moment, I'm thinking it was most likely a high primer that slipped through QC, possibly in combination with a stuck firing pin. If that's the case, I've addressed the firing pin issue and will step up my QC a notch.

If that wasn't the case, I'll surely know in the next thousand rounds or so.

BB

[CSEMARTIN]

BB, please let me know how this all works out. I'd like to know. Thanks.

[bbbean]

BB, please let me know how this all works out. I'd like to know. Thanks.

Will do. I'm going to leave things as they are the rest of this week and through this weekend's match. Next week, I'll replace mainspring and recoil spring (they're due for replacement anyhow). I think the sear spring is in good shape.

[jjanglin]

BB, please let me know how this all works out. I'd like to know. Thanks.

Will do. I'm going to leave things as they are the rest of this week and through this weekend's match. Next week, I'll replace mainspring and recoil spring (they're due for replacement anyhow). I think the sear spring is in good shape.

BB:

Be sure and polish the tag ends of the springs before you put them in the gun,more than likely your slam fire was caused buy

the fireing pin /spring if the long fireing pin I put in it is still in their.New fireing pin spring is in order.

Jim/Pa