At the range the other day I noticed that a DA trigger pull would result in a light strike. Obviously a decock action had to occur first. There were zero light strikes on single action functions. This was all through the same reloaded ammo. I am certain the primers were seated properly and it was not a case of hard primers. I am at a loss to understand why a DA hammer strike would be light as compared to a SA hammer strike. I will be taking some factory fresh ammo to the range next time to test.


Any thoughts as to what may be the reason, thx.

You're not "riding" or putting any pressure on the decocker when you grip the gun, are you? That can put pressure against the hammer and reduce the impact of the hammer against the firing pin when it falls. I'm not saying you are...but it's easy to do with a small grip like on the P239.

I don’t think so but I’ll be careful next time I’m out. Grips are G10 and there does not seem to be much flex in them. Thumbs high grip doesn’t put too much pressure in decocker area.

Hammer cocks farther back in SA. I recommend a complete detail strip and inspection.

Firing pin channel gummed up, maybe?

quote:

Originally posted by SigSentry:
Hammer cocks farther back in SA. I recommend a complete detail strip and inspection.

This pretty much explains what is going on. To be more specific when you cock the hammer for Single action you pull it past the position where it drops in Double action. As a result a single action shot will have the hammer started at a position where the mainspring is more compressed so it produces more power in the hammer strike.

I will also note that when the P239 was a very popular carry choice many shooters would "lighten" the DA trigger pull by installing a weaker mainspring. I never did that with mine because A) I practice a lot with DA revolvers and B) because it can produce the exact issue you are contending with.

My suggestion for a correction for this problem would be to see if you can obtain a new factory mainspring and install it in your gun. Note it's been years since I did any work on my P239 but my memory is that replacing the mainspring was not at all difficult.

Link to the mainspring at Top Gun Supply

https://www.topgunsupply.com/s...9-239-old-style.html

Just back from the range. Prior to my trip I made sure everything was lubricated properly. No binding was found anywhere on inspection. I took along reloads and factory fresh. I am happy to say there were no light strikes at all, everything went as it should have. What was the problem, I don’t know. Thx for the suggestions

Two easy checks. Trigger and hammer held back, push on the rear of the firing pin with a Q-tip or similar to "feel" the resistance. It should be smooth compressing against the firing pin return spring.

Pencil test. Gun unloaded to avoid pencil going through roof. Point gun up with eraser end of pencil in the barrel, dry fire and check how far the pencil launches.

Aside from gunk in the firing pin channel, other things that might slow the firing pin down would be the firing pin block safety not completely clearing the FP channel. This can be due to the safety plunger not being lifted high enough, so the FP gives the safety plunger a glancing blow, robbing it of power. This is usually a result of worn parts such as a worn top "nub" of the firing pin block safety lever. The firing pin retainer pin may be damaged or broken - this would also likely show up when "feeling" the FP resistance.