I recently purchased a model 19-5. The gun very frequently fails to fire in the double action mode (about 90% of the time). When fired in the single action mode the gun fires every time. I have tried several brands of ammo with the same result. Any help would be appreciated.

In single action, the hammer hits the primer just slightly harder than it does in double action. This is because the hammer doesn't come back quite as far in double action, thus the spring doesn't have as much energy to give to the hammer.

Make sure the mainspring tension screw on the front of the grip is tightened all the way in. A lot of people loosen this screw just a little because it makes the double action lighter and smoother. The tradeoff, as you found out, is reliability.

It's also possible that somebody has substituted one of the popular after market spring kits for the factory springs. They usually, but not always, work OK. If tightening the strain screw doesn't eliminate your problem, look at the main spring to see if it is factory or has been ground down.

Another thing to try if the screw is tight. Take the mainspring out and lay it flat if it's bent flatten it out a bit. If you notice it has a rib in the middle of it it's most likely an aftermarket reduced power spring and you would need to order a new factory mainspring.

I will suggest that you check one more thing which I have encountered on two Model 19's over the years. It's RARE but I have two 19's that have the Coke (target) style factory grips on them, and the grip screw is SLIGHTLY in the wrong place (too far forward) causing the main spring to hit it. When this occurs, the spring will not come back to develop its full power. In double action mode the hammer falls slightly before it does when in the single action mode creating less of a force to ignite a primer. Now being that I personally have two 19's with this situation, I know there are others out there. Both of my guns fired 100% single action, but did FTF quite often on DOUBLE ACTION before I fixed them.

OK, so here is the fix IF your 19 falls into this category. I had to modify the grip screw by decreasing the diameter in the middle section so that the spring no longer hit up against the screw shaft - this in turn allowed the spring full movement. When you are done with this modification your grip screw kind of looks like a barbell, thinner in the center, larger on both sides. Another fix is to try a different set of grips, but in my case I like the Coke grips.

IF this is not he case with your model 19, I would make sure the strain screw is all the way in and tight. I would also check to see if someone cut the screw or ground it down causing the spring to develop less power. If that does not apply to your situation, then I would replace the main spring.

regards,
chief38