Need help with a new GP-100

Derek Zeanah

Derek Zeanah

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Just bought a new Wiley Clapp 3" GP-100 with a 7 round cylinder. Love the feel and the sights, seems like a good gun.

Today I went and shot it with some cheap 38 SPL ammo (125gr TMJ) and some Remington .357 125gr SJHPs. The problem I'm running into is this:

Sometimes the trigger pull gets very heavy. Like, if it's a 9 lb trigger pull, it will crank up to 30lbs (not measured, just extremely high). I can't tell that anything is hanging up, but it happened on every cylinder of 38, and 2 out of 3 cylinders of 357 (though on fewer rounds in the cylinder - instead of 3-4 it might be 2, but it's still there). When this happens it takes more effort to release the cylinder, but I'm not seeing anything wrong with the brass, and I can't tell that the rounds are touching each other in the cylinder. This is the latter half of the trigger pull where I'm mostly experiencing this, though a couple of times I noticed, let the hammer back down, and the cylinder hadn't advanced so maybe it's not that late in the pull that it's happening.

Note that I shot this dry - I'd never fire a 1911 without making sure it was nice and lubed up first, but I'm new to revolvers and if they need more care than this then I'm unaware of what to do.

Note that these all fire fine through Taurus and S&W revolvers. Same ammo, new gun, only happens in the new gun.

Any ideas?
 
Others will have more knowledge but this sounds to me like the transfer bar could be hanging or dragging in the frame. But you'd have that dry firing too. Does the trigger guard appear smoothly fitted to the frame? It should look almost seamless.
 
The one GP100 I had experience with needed a trigger job. I don’t mean I preferred to have the trigger done, it NEEDED a trigger job. It literally squeaked as it was pulled. Not the same exact problem you’re having. The expert revolver guys here might know exactly what’s rubbing or hanging up on yours.

I would lube it up and dry fire it and see if the problem continues. If not, load snap caps or fired brass and see if the problem continues.

No matter what, if it was mine, I would do a trigger job. LOTS of other people have complained about the trigger on GP100s. But, the one I did ended up being the smoothest, slickest trigger I’ve ever pulled. They can be made to be great.
 
Just put 4 more cylinders down range after a quick lube job. Remington 158gr LRN this time.

1 particular round was doing this every time. The one to the left of the red mark on the extractor:

IMG_1900.jpeg

Consistent that round.

Here’s where in the cycle it’s happening:

IMG_1898.jpeg

At that point the trigger is just hard to move. Swing the cylinder out, and the same round has the same problem next time.

Strangely, when I put a spent round in there and dry fire it’s fine.
 
All the new GP100s I've messed with in years have needed a trigger job, but I don't think that's the problem here. Needing a trigger job would make the trigger gritty and stiff, but it should be pretty consistently stiff and gritty.

It sounds like the cylinder is either not turning freely, or something in the cylinder/crane assembly is bent and is obstructing/grabbing/catching during part of its rotation.

Swing the cylinder out. Spin it and then turn it slowly through a complete revolution while watching it carefully. There should be no trace of a wobble. It should turn very easily without any hitches or catches.

If you can detect a wobble or if there's a noticeable catch/hitch during the rotation then it's time to call Ruger.

It's also possible that there's something wrong with the "star" on the back of the cylinder that the pawl/hand engages. One of the teeth might be damaged/malformed and causing a problem when the hand tries to rotate the cylinder. I think that's less likely.

I was posting this as you were posting. After reading your post, here's another possibility.

Maybe one chamber is cut slightly shallower than the others and that's holding the round back slightly and making it harder to turn the cylinder when that round is being rotated under the firing pin. That might account for why it isn't an issue when you put an already-fired case in that chamber and test it. The point where it's hard (in your picture) is right when the round is being cammed forward by the ramp on the frame so that it's fully seated in the chamber.
 
Check the barrel/cylinder gap on that chamber and the one before it, and see if you're getting drag there. You'll need to have fired brass in the chambers to avoid end shake misleading you.
 
I can’t detect a wobble. And the barrel cylinder gap seems pretty tight. (I’ve got old eyes now)

Here’s from the chamber with issues

IMG_1901.jpeg

And here’s another for comparison

IMG_1903.jpeg

And just to make sure that’s not just my photography, here’s a Taurus.

IMG_1905.jpeg

Looks like it’s off kilter a bit (but I'm no revolver expert.)
 
If you have a good eye, you can watch the barrel/cylinder gap while you cycle through one entire revolution. Or you can get a set of feeler gauges and check the barrel/cylinder gap with each chamber under the cylinder. The measurement isn't important, only whether it's consistent from chamber to chamber.

Also, maybe one chamber is cut slightly shallower than the others or there's something else obstructing the round from initially chambering fully and therefore making it harder to turn the cylinder when that round is being rotated under the firing pin. That might account for why it isn't an issue when you put an already-fired case in that chamber and test it. The point where it's hard (in your picture) is right when the round is being cammed forward by the ramp on the frame so that it's fully seated in the chamber.
 
JohnKSa said:
Also, maybe one chamber is cut slightly shallower than the others or there's something else obstructing the round from initially chambering fully and making it harder to turn the cylinder when that round is being rotated under the firing pin. That might account for why it isn't an issue when you put an already-fired case in that chamber and test it. The point where it's hard (in your picture) is right when the round is being cammed forward by the ramp on the frame so that it's fully seated in the chamber.
Click to expand...
Just in case I have one final data point (it's easy to shoot on your own property, but the mosquitos are coming out to start charging a toll and I don't want to pay it):
  • I took out a brush and some CLP and scrubbed the rear of the cylinder until it looked new and shiny. Lost my red mark, unfortunately.
  • 1 cylinder full of 158gr LRN loaded
  • First 3 rounds fired fine, then the 4th locked up
  • I swapped the 4th and 5th round - same issue. Different round in the same chamber and was still feeling the lockup
  • Advanced past the problem chamber and all shot as expected
  • Cycled through the cylinder again and got 6 clicks and a final bang on the problem chamber. Trigger pull was ... like the others, but usable at 7 yards on poppers.
So it's not as consistent as I thought.

(And who would you send this to for a trigger job and to chamfer the chambers a bit so reloading is easier?)
 
Looks to me like the cylinder face isnt machined flat- the gap is tighter towards the top strap.

Can you put a little forward pressure on the cylinder as you pull the trigger (gun empty) and get it to drag on the barrel extension?

OT (a bit) but the way Ruger is now turning the cylinders thinner at the charge hole end makes my eyeballs physically hurt.
 
Another thought- you may be able to tape off the cylinder stop holes to prevent the bolt from dropping into its recesses, then spin the cylinder while watching to see if the gap visually changes as you rotate it. This works on S&Ws but I forget if Ruger hands will allow it.
 
Last edited:
Just a thought in relation to what JohnKSa said: Did you try shooting
the gun but leaving the "offending" chamber unloaded? If it works OK
with the one empty chamber, it's a point to mention when or if you
send the gun back to Ruger. The company has excellent customer
service and usually quick turn around times.
 
I suppose that one hole may not be step-bored deep enough as well, resulting in the cartridge rim hitting the blast shield as it comes around into battery. Make sure the cartridges are seating fully in that hole compared to the others.

Although, now that I think about it, that might be a problem with .357 brass, but shouldn't be an issue with .38s....

That hole could still be out-of-round, however. Which might also prevent fully seated cartridges.
 
The trigger pull is having to cam the round into one of the chambers which would make the pull for that chamber tougher than the others. Once you get the round cammed in, it's in and so the next time you cycle the cylinder it won't have to cam the round in and the pull should be the same.

Doing feeler gauge measurements on the barrel cylinder gap should provide some insight.

I am liking the short chamber theory less since I see you are also shooting .38Spl ammo and having the same issue with it.
 
It might be the photo or my old eyes but your photo of the b/c gap looks like the gap is smaller at the top than the bottom. Do you see any evidence the cylinder is dragging on the barrel at the offending chamber face? I'd check the gap on each chamber to see the variance with some automotive feeler gauges. Does it happen when dry firing? Good luck.
 
Last edited:
I‘ve never seen a GP100 with a problem like this. Based on your post it appears to only be doing this with one chamber after you applied lube. Is the hammer more difficult to cock on this same chamber? If the stacking trigger pull only occurs with rounds in the chamber and not when the gun is empty I suspect you have a headspace problem with some rounds that have slightly thicker rims dragging across the breech face. I had a similar problem with a Vaquero several years ago…only difficult to cock on ocasion. Look at the breech face. Any brass marks across the breech face? Any drag marks across the cylinder face? Something is binding up…look for drag marks. That will tell the story. In any event you will have to return it to Ruger. They will repair it quickly.
 
I had a S&W 686-6 Snub that fired all but the one chamber sent it to S&W when returned notes on repair said timing issue
 
Derek - your pictures in Post #7 were good enough to seem to show the cylinder's face rubbing against the forcing cone at the top (right side of the picture) while the side nearest the center shows a sliver of light through it. The fact that the second picture clearly shows an even spacing makes me wonder if the cylinder was not properly machined at the factory.
I agree with others - contact Ruger and ask them if they will have a tech look at the pictures before sending the gun back to get their suggestions.
Good luck !
 
Derek Zeanah said:
Just put 4 more cylinders down range after a quick lube job. Remington 158gr LRN this time.

1 particular round was doing this every time. The one to the left of the red mark on the extractor:

View attachment 1163044

Consistent that round.

Here’s where in the cycle it’s happening:

View attachment 1163045

At that point the trigger is just hard to move. Swing the cylinder out, and the same round has the same problem next time.

Strangely, when I put a spent round in there and dry fire it’s fine.
Click to expand...
That primer in the middle case looks like it has been dragging on the frame. Possible high primer?
 
No expert here, just some suggestions. As mentioned, gauge the gap for each chamber/charge hole. Might try putting spent rounds in and color the front face of the cylinder (at forcing cone) with a sharpie, then dry fire a few cycles to see if the sharpie rubs off on any particular area. The early 7 shots had some issues with the rims overlapping each other, but not sure if that's an issue. Curious why the middle round in one of the photos isn't seated like the other two.
 
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