Hammer block & sticky rebound on pre-10

[jtcarm]

I have this 1953 M&P .38 that had a trigger pull like a ton of bricks. So I took it apart and did my standard smoothing job: lapping/homing DA trigger & hammer sears, cylinder stop, rebound slide, sides of trigger & hammer, sides of the hammer block, and ground a little from the sides of the main spring. Rebound spring wasn't touched.

Now with the hammer block installed, the trigger rebound tends to stick sometimes and not return completely. It's fine without the hammer block installed. I can only surmise the block is catching on something on its way back up, but I sure can't figure out what. I tried polishing the little mortise in the side plate where it moves, no help.

It slides up & down smoothly in the side plate groove as well as over the sides of the hammer when the side plate is off. Only when everything is assembled does it cause a problem.

Any ideas?

 

[steelslaver]

Any chance it is not dead flat? Do you have one from another gun you could try? Any way the slot on the hammer block is hanging on the pin a bit?

 

[armorer951]

contrary hammer block

Many times the very top edge of the hammer block gets hung up on the hammer, as the block makes it's way up between the hammer and the frame during the trigger return cycle.
If you have a stone or a small file, you can knock off the sharp edge on both sides of the very top of the hammer block. This should eliminate the contact.

If you want to confirm the point of contact/interference, you can stain the top of the hammer block with some Dykem or a Sharpie and then install and dry fire the action. This will show where the contact is occurring on the hammer block. Most often, it will be on the "back" corner....or the corner that faces the hammer when the block is installed.

 

[jtcarm]

Thanks guys! Both those ideas had occurred to me, but I hadn't had time yet.

Knowing the likely point of contact helps immensely.