I bought a CZ512 in .22 WMR and I like everythig about it except the trigger pull. It is notchy, stiff and has a lot of travel. Upon dis-assembly it is obvious the the stiff notchy feel is due to rough machining on the hook area of the hammer and the trigger. I spent a couple of hours polishing both pieces which improved the effort and notchy feel an incredible amount. I clamped a lenght of smooth steel strap in the vise and folded sand paper over it. Started 1000 grit, then crocus cloth and ended up with a mirror finish on both parts. NOTE: BE CAREFUL NOT TO REMOVE ANY MATERIAL, JUST POLISH THE SURFACES OR YOU WILL WIND UP WITH AN UNSAFE RIFLE (FULL AUTO) Reassemble and check often during the process, the disconnector must touch the hammer before the trigger breaks or it will double fire or go full auto.
You can see here the rough finish on the hammer.
Keeping the parts oriented so the flats are aligned with the flat edge of the steel I worked the parts back and forth until and even finish was achieved
Hard to get a decent picture of the polished area but you can see in this one part way through the process that it's is getting pretty smooth.
This is how the 2 parts interface
The polishing alone has reduced the trigger pull from over 7 lbs to 3 lbs but there is still alot of travel and you can see in this pic how much hook engagement there is, that is causing the long travel.
I made up an aluminum block and drilled and tapped it for a 8-32 machine screw to make the travel adjustable, it holds the trigger slightly forward of it's fully rearward position.
The aluminum block is an interferance fit into the trigger housing and 1 hole had to be drilled through a web in the housing for the screw to pass through and thread into the block. The hole in the top of the block is only so a screw can be installed to use as a handle for removal of the block.
I reduced the hook engagement to about 2/3 of what it was. Here you can see before and after hook engagement.
I haven't had it out to the range yet but the trigger feels great now with smooth travel and about 3 lbs pull weight.
You can see here the rough finish on the hammer.
Keeping the parts oriented so the flats are aligned with the flat edge of the steel I worked the parts back and forth until and even finish was achieved
Hard to get a decent picture of the polished area but you can see in this one part way through the process that it's is getting pretty smooth.
This is how the 2 parts interface
The polishing alone has reduced the trigger pull from over 7 lbs to 3 lbs but there is still alot of travel and you can see in this pic how much hook engagement there is, that is causing the long travel.
I made up an aluminum block and drilled and tapped it for a 8-32 machine screw to make the travel adjustable, it holds the trigger slightly forward of it's fully rearward position.
The aluminum block is an interferance fit into the trigger housing and 1 hole had to be drilled through a web in the housing for the screw to pass through and thread into the block. The hole in the top of the block is only so a screw can be installed to use as a handle for removal of the block.
I reduced the hook engagement to about 2/3 of what it was. Here you can see before and after hook engagement.
I haven't had it out to the range yet but the trigger feels great now with smooth travel and about 3 lbs pull weight.
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