Grip Screws and Hammer Struts: Trouble Shooting a GP100

[WrongHanded]

When I bought it, it was rough. I've never handled a smooth GP100 out of the box, so no big deal.

I did a trigger job and added shims (first time for that), which I thought smoothed it out quite a bit. Then I installed new sights, and to finish off I added an Altamont wood panel and rubber grip. It looked good, the action was better (though not as nice as my other GPs which have had less work), so I was pretty happy. I figured it'd smooth up more with use.

After a break from shooting it, I came back to the gun. The trigger was terrible. Heavy and gritty, and thoroughly unacceptable. But nothing seemed to be really wrong. I decided to put lighter springs in, and ordered a spring kit. It came, and I installed a 10# trigger return spring, and 10# hammer spring. It felt really nice, so I put the grip back on.

Whoa! The DA trigger is again gritty, rough, and heavy! The SA hammer pull is the same way. I took the grip off to inspect it yet again, and everything is suddenly back to being smooth. Then I notice the wear on the grip screw.

The hammer strut (which is, and has, been installed correctly the whole time, and yes I did check) has been running across the grip screw, causing drag and grinding the surface of the hammer strut.

I ended up putting a few drops of oil on the end of the hammer strut (to help it polish itself back out on the strut retaining bracket), and installed a Hogue grooveless monogrip. It''s smoother than it's ever been, and hopefully it'll stay that way whilst still setting off every primer struck by the firing pin.

Of all things, a grip screw was the problem with the action. I never would have guessed.

 

[MrBorland]

I’ve heard of this happening with S&Ws with non-mono rubber grips and have cautioned folks against over tightening the screw: when the screw is really honked down, the grips can pinch the mainspring and affect the action and reliability.

 

[MidRoad]

I have a set of of Thia grips for my gp100 (don't use them now) ,and noticed that guy put his screw hole extremely close to the hammer strut, I was trying to make up a spacer to slip over the screw to support the center of the grip and couldn't find something thin enough ,but nohing would clear, even ground down a roll pin with a drill and bench grinder so it was super thin ,still no luck. Prior planning prevents piss poor performance I guess.

Stupid question but did you use the grip locator pin?

 

[WrongHanded]

Stupid question but did you use the grip locator pin?

I sure did. It seems like these particular grips are just out compatible on this particular gun. It may even be that the strut retention plate or whatever it is called has just a little too much play forward and rearward. I didn't measure the gap, but it might be approaching 3/64". This may have allowed the strut to move into an area that the grip maker simply didn't account for. Or maybe the grip screw holes are just slightly out of place relative to the holes for the grip locator pin on the panels. Maybe it's both.

But either way, I'll test fire the gun tonight with some reloaded practice ammo, and some carry ammo. Hopefully the 10# hammer spring is enough for it to be reliable.

 

[ThomasT]

Its funny the things that can cause function issues. I bought a used SP-101 and the original owner had cut the springs trying to reduce the pull and drag of the trigger. So I took apart and did a polish job on the trigger group. I ordered new springs from Wolfe. Nothing helped. So I took it apart around 10 different times trying to smooth it it.

One of the times I noticed that there was a drag mark on the top of the trigger group housing. Then I looked at the bottom of the hammer. Sure enough Ruger had left just enough metal on the bottom of the hammer that it was rubbing on the top of the trigger housing. With just a few strokes from a file and the extra metal was removed and smoothed out.

I put the gun back together and wow what a trigger pull I had. It is SMOOTH and easy and works like a S&W trigger. I can lay a penny on the barrel and dry fire it 20+ times double action before the penny bounces off. But it took me a while to find that one.

 

[WheelGunMan]

Who'd have guessed!?! Definitely adding that into memory in case I run across the same problem. Thanks for sharing!!

 

[Drail]

There are revolver grips of the market which are so poorly designed the screw will not clear the hammer strut because the screw is in the wrong place. I used to see this quite a lot with Pachmayrs on a S&W that had a light spring kit dropped in. It is something you should always check for when installing non factory grips. Another reason I like Hogue's monogrip design that attaches to the bottom of the frame.

 

[IWAC]

Good on you for figuring it out! I changed the wooden grips on my Match Champion for the original rubber with inlay style, which feel much better (more familiar?) to my hand. No grip screw dragging that I can notice. I also did a minor polish and installed lighter Wolff springs, which smoothed stuff up greatly. It is a real woollybugger to disassemble. I pull on the trigger assembly, while my wife hammers (GENTLY Wife!) on the grip nub, and it comes apart pretty well, but, is very tight, requiring a tap or three with a rubber hammer to get it back together. And, the hammer shims are a real pain to get back where they belong! But, that's not altogether a bad at all atall. Replacing the mainspring with a Wolff 12 lb, and the return spring with Wolff's 10 lb. one lightened the double and single action pulls nicely, and still give reliable ignition.