new MK IV

[mirglip]

I didn't keep my mk4 long enough to worry about replacing any trigger parts. But... my 1st mk3 had a HORRIBLE grooved sear that gave a pull of over 7lbs.

I replaced the sear with a VQ and the pull dropped to a very nice 2.2lbs. A couple years later, I was bored and decided to see what I could do with the original Ruger sear. After I got the mating surface shiny smooth, I put it back in. It came in at 2.3lbs. Close enough to the VQ that you couldn't tell the difference without a pull gage.

That said, I don't recommend working on hammers or sears without a jig. Power Custom makes a good one. Mine was makeshift, but it was good enough for the one-off test with a trash sear.

I have replaced several Mark II sears with Volquartsen sears and compared the Ruger sears to the Volquartsen. The latter has a more aggressive sear angle. Most likely the factory sear is case hardened. I was tempted to work over the factory sears but I was worried I'd go past the thin case hardened layer and the trigger would fail later.

 

[TestEngineer]

I was worried I'd go past the thin case hardened layer and the trigger would fail later.

That is a legitimate concern. From what I can tell, the hardened layer is between 5 and 7 thousandths thick. You should be fine with only smoothing and polishing the mating surface. But more aggressive modding should be followed with re-hardening. You can buy case hardening paste and activate it's action with a small torch.

I did modify a sear to have a breakaway angle based on one forum gunsmith's recommendation as a way to reduce creep. The result was the crisp break was replaced with an incredibly smooth release. Creep was not reduced all that much. But the mod penatrated the hardened layer and the sear failed several months later.

This was another learning experience. I learned that if I want a super smooth release, it's necessary to split the sear first and add the breakaway to only the area that meets the hammer. And then re-hardening the newly exposed surface.

I don't shoot in bullseye leagues, so I haven't chased this rabbit very far. But if I did, I do know how to get an incredibly nice trigger.

 

[mirglip]

That is a legitimate concern. From what I can tell, the hardened layer is between 5 and 7 thousandths thick. You should be fine with only smoothing and polishing the mating surface. But more aggressive modding should be followed with re-hardening. You can buy case hardening paste and activate it's action with a small torch.

I did modify a sear to have a breakaway angle based on one forum gunsmith's recommendation as a way to reduce creep. The result was the crisp break was replaced with an incredibly smooth release. Creep was not reduced all that much. But the mod penatrated the hardened layer and the sear failed several months later.

This was another learning experience. I learned that if I want a super smooth release, it's necessary to split the sear first and add the breakaway to only the area that meets the hammer. And then re-hardening the newly exposed surface.

I don't shoot in bullseye leagues, so I haven't chased this rabbit very far. But if I did, I do know how to get an incredibly nice trigger.

I hadn't thought of re-hardening the sear, but that's a good idea. I will have to read up on that. Just going on memory, I would say the difference between the Volquartsen sear and the Ruger sear was about 20 thousandths.

 

[mirglip]

I bought a 40190 Mark IV 22/45 and a Volquartsen accurizing kit. I'm trying to install the kit but I can't find any instructions or video showing how to do this. All I found is instructions and videos showing how it's done on a Mark IV non-22/45. I've been trying to adapt those instructions to the 22/45 but it's too different. I got the hammer and sear etc in according to instructions but now I have to completely dissassemble it to re-install the mag release.

 

[Johnnu2]

pilgrim, I THINK I used Volquartsen's video, but I just can't remember sit anymore....

J.

 

[mirglip]

pilgrim, I THINK I used Volquartsen's video, but I just can't remember sit anymore....

J.

Thanks. That's what I'm using, but they don't mention the mag release in that video. I found the info elsewhere. During re-assembly, my bolt stop release spring vaporized so I'm out of commission until I find a replacement. I used up my entire repertoire of vulgar language. I'll have to think up some new ones.

 

[fwb124]

I sympathize.

I just spoke to Victor at Volquartsen about your issue, and he recommended the second half of the installation video for their laminated grips for the Mark IV 22/45, found here:

https://volquartsen.com/howto/install_mk4_2245_laminated_grips

He also pointed out that the only three differences between installation of the accurizing kit into the 22/45 and Target grip frames are:
1. You need the additional, included spacer for the sear. (My bad on the hammer, corrected to sear per mirglip,)
2. You use the alternate, shorter overtravel screw in the trigger.
3, The 22/45's magazine release's spring indexes on the trigger's cross pin, which it doesn't on the Target frames, which adds additional trickiness to the 22/45 install.

I decided to reach out partly because I've done a couple of Mark IV Target frames, but I still have one 22/45 frame to do as well, which I haven't before either.

Hope this helps.

 

[mirglip]

You need the additional, included spacer for the hammer.

Thanks for the informative post. I hope you meant sear, because that's where I put the spare washer.