K Frame Push Off Information

[Retired W4]

I was about to swap trigger and hammer on my 2" 15-3 due to push off. It did require a pretty good push to make the hammer drop, but any push off is too much for me. Any way, after looking at the mating surfaces, which did not look like they had been messed with, and doing some detailed cleaning there, the push off is gone. All I can think of is some foreign object interference from the last time it was taken apart.

It does have a 2 pound SA pull (9 DA) so it will take some shooting of this thing before my confidence level comes up.

 

[armorer951]

Based on your measurement of the SA pull at "2 pounds" the rebound spring has probably been modified, or a lower rated "aftermarket" rebound spring has been installed at some point. Increasing the rating of the rebound spring can help bring the SA pull back up to an acceptable rating. (3 pounds)

Use caution when applying pressure to the hammer when checking for push off. Too much pressure here can damage the cocking notch on the hammer, and/or the bevel on the trigger.

Added from earlier thread: additional push off information.......

Push off testing and comments:

The manual calls for "nominal" pressure to check for push off, which to me has always been around 8-10 pounds. (If you need to quantify this pressure rate, use a trigger pull gauge to pull on the hammer.) This was confirmed by the instructors at the S&W armorers school. Any hammer trigger interface will push off if subjected to undue pressure.

Extremely light trigger pulls can also be a telltale sign of tampering and push off issues. If you have a trigger pull gauge, check to see if the trigger pull is around 3 pounds. Anything below 2.5 pounds is an indication of possible modification, spring rate changes, tampering, or excessive wear and tear from use.
(Excessive hammer or trigger sideplay can also contribute to push off)

There is a bench procedure to repair push off that works very well, as long as the bevel on the trigger and the cocking notch on the hammer are in-tact, undamaged, and unmodified. A specific sized India stone and technique are required.

Unless you are familiar with S&W's "benchtop" method of sharpening the trigger bevel, ask a trusted local gunsmith, if you are fortunate to have one in your area, if he would check the SA and provide an opinion concerning the integrity of the SA interface.

You might also check to see if the rebound spring currently in the gun is a factory spring with 17 coils. A lighter aftermarket spring, or a spring that has been cut can contribute to push off.
Replacing the lighter rebound spring with a full length factory spring will sometimes solve the problem, without any further intervention or modification.

 

[Retired W4]

Thanks much. I will take it back apart to see if the rebound spring has been modified. 2 pounds is too light for a carry type piece I believe.

And good info on checking for push off.

 

[jjrr]

May also be a good idea to check the integrity of the gauge that gave the trigger pull readings. I spent my working years calibrating measuring instruments and spring gauges are not known for accuracy. Don't mean to start argument or question someone's gauge, if you trust yours that's great.

 

[Retired W4]

May also be a good idea to check the integrity of the gauge that gave the trigger pull readings. I spent my working years calibrating measuring instruments and spring gauges are not known for accuracy. Don't mean to start argument or question someone's gauge, if you trust yours that's great.

This Timney is fairly accurate gauge based on my last check. I will take several readings, which do vary some, and take an average. In the case of this 15-3 the SA is actually approximately 1.8# on average. I'm in the middle of two other projects now so I will take it apart in the AM and report back.

 

[Retired W4]

I replaced the rebound spring this morning with a new Wolff 15 pound spring. The SA is now 1.75#. These usually give me 2.75-3# SA but not on this gun. I'm starting to think someone has done a little too much polishing on the trigger/hammer surfaces. As for the push off, it did it once and then could not be repeated. DA pull is 10 pounds.