K frame trigger bind

[GM4spd]

New TT in a K frame. Binds up after trigger pull thru, if I loosen the yoke screw from its fully tight position about 1/4 turn it will
functional normally. The old trigger doesn’t do this after fully tightening down the side plate. Any thoughts ? Thanks

 

[Protocall_Design]

Measure the thickness of both triggers. The new one is probably a couple thou. wider. You can lay a flat file across the hammer and trigger bosses on the sideplate and file them a bit. They are almost always crooked anyway, so a bit of flattening is a good thing. The 2 bosses around the pivot pins are above the rest of the sideplate. You only want to dress off just enough to make them (mostly) flat. That's a thousandth or 2 max.

 

[sndbggr1484]

Maybe one of the pins is sitting proud of the side of the trigger. A simple tap of the the pin to make it sit flush will cure this if that is the problem. Look at the frame and side plate for drag marks left by the pins.

 

[Rolandag2]

Protocall is correct, side plate would have to be fit to new hammer and trigger. If new trigger is binding and old one wasn’t, and yoke screw tension increases bind on trigger when tightened indicates that trigger pin boss on side plate needs to be dressed a bit and rechecked until trigger moves freely

 

[GM4spd]

Thanks for the help. Here are pics with thickness around the hole where
trigger pivots. Top pic is old trigger 6.63 mm thick. New at the bottom is
6.73 mm thick. Where do I apply stone on the new one to reduce thickness?

 

[Rolandag2]

Not on the trigger but the side plate trigger pin boss

Take a small diamond file and dress it a small bit and recheck the side plate with screws tightened until the drag gets easier then use a fine Arkansas stone to finish dressing it

 

[Rolandag2]

Use your caliper/micrometer to measure the thickness of the trigger pin boss then remove .010 off, then finish with a fine Arkansas stone until it fits prefect remove a little bit then test and refit, keep going until it fits perfect

 

[GM4spd]

Thanks again,I see what I need to do. I’ll post pics when I get it right. Pete

 

[Protocall_Design]

I would only remove .001 at a time. It's likely .001 or .002 will do it. Taking .010 is too much. Lay the file or stone over both the hammer and trigger boss to keep them level and parallel to the sideplate.

It's a good idea to deburr the rest of the sideplate while you're at it, filing it all flat. Be careful to work around the 2 bosses, as they are on a higher level than the rest of it.

 

[Rolandag2]

Protocall you’re absolutely correct that’s what I meant to write .001 at a time

 

[Protocall_Design]

Misplacing the decimal point is easy to do. It happens on the machinist forums, too.