Saturday, May 19, 2007

Trigger job for your Ruger GP100

Ruger GP100s are reliable revolvers that are a lot of fun to shoot. Unfortunately, out of the box, the trigger pull is heavy and the trigger can be "stagy" and rough.

However, with a little elbow grease, a set of miniature files ($26.45 from Brownells), a ceramic stone ($29.95 from Brownells) and a set of Wolff Gunsprings springs ($10.50 for a shooters pack) one can do-it-yourself, acquire some knowledge and tools for future trigger jobs.

After taking off the stock, the first step is to remove the hammer strut and hammer spring. There is a hole at the base of the hammer strut. Cock the hammer back and stick a toothpick into this hole, all the way through the hole.

Now, release the hammer by gently squeezing the trigger while holding the hammer, and letting it gently fall. The toothpick will hold back the hammer spring and the spring and hammer strut can now be removed as a module.

The hammer is free to move without spring pressure. Now, pull the hammer back and gently drive out the hammer pin using a chopstick or other non-marring rod of similar diameter. The hammer can be removed out the back of the revolver.

The next step is to remove the trigger group. Using a chopstick (or other non-marring rod of similar diameter) push on the detente pin on the inside of the revolver grip.

While pushing on this pin, with the other hand pull down on the trigger guard. Once the detente pin is free of the hole in the grip frame, you should be able to cantilever the whole trigger group down and forward.

At this point, the trigger sear and hammer engagement surfaces should be visible. The goal of polishing these surfaces with a stone is to ensure the removal of all manufacturing burrs and blemishes and thus guaranteeing smooth movement of metal surfaces over one another. When polishing with a stone, do so slowly taking off a little metal at a time until the desired surface is achieved. It's preferable to apply pressure on the stone only when moving in the direction towards that of an edge. Never stone an edge itself.

First, stone the trigger sear engagement surface.

Next, stone the hammer engagement surfaces.

At this point, you should check the hand slot and the cylinder lock slots, respectively, for manufacturing burrs. Burrs in either of these slots will result in drag and catching of the hand and/or cylinder lock respectively.

What's the hand slot you ask? The hand is the piece that rotates the cylinder of the revolver and it sticks through the hand slot in the back of the revolver.

Similarly, the cylinder lock is a piece that pokes up through the cylinder lock slot in the bottom of the revolver. It locks the cylinder it place so it doesn't move while firing.

With both slots, check that the hand and cylinder lock, respectively, move freely and easily. If not, very carefully file the inside of the slots with a miniature square file, removing any burrs or blemishes as necessary. Be very careful to remove only a small amount of material at a time, and only as much as is necessary to achieve free movement.

Two springs should be replaced to lighten the trigger pull; the trigger return spring and the hammer spring.

Remember the detente pin you pushed in to remove the separate the trigger group from the frame? The trigger return spring is right behind it. The weight of this spring, singularly, determines single-action pull weight.

The hammer spring is being held back by the toothpick on the hammer strut. Carefully separate the hammer strut and hammer spring by extracting the toothpick. Do this someplace without a lot of dark nooks and crannies, in case you have to chase the spring. :-) The weight of the hammer spring is the primary contributing factor to the double action pull weight, and secondarily to the single action pull weight.

For the trigger return spring and hammer spring, I recommend 10 lbs and 12 lbs, respectively, if you buy the shooter's pack mentioned above, you can experiment.


Weetabix said...

Thanks, Felix. I have no wheel guns, but I get immense vicarious pleasure from seeing how others improve their guns. Feel like doing any posts on how to improve a Mosin?

Felix Estrella said...

Could do. I do have a 91/30 with a very heavy trigger pull. Let's see what I can put together.

Weetabix said...

I have a 91/30, M38, & two M44's. I'm thinking I might buy some parts at the next gun show to practice on, then assemble one good trigger set up on one rifle, if possible, or clean them all up. I guess I'd be somewhat concerned about mixing and matching that sears/bolts might not match up well enough.

At any rate, I eagerly await your next installment.

Felix Estrella said...

Sears and triggers are interchangeable. Bolts and receiver/barrel combos should not be mixed/matched.

JALewis said...

Ah Felix, yur tha man. I've been looking all over for a good DIY for my 3" gp. The trigger is horrible! Btw, I wonder what would Jesus do/say about the possibility of global warming!?

Anonymous said...

I reckon he'd make some friends and then just end up getting himself killed again.

Great trigger article. I have a Wilson Combat spring set for the GP100 and now I'm more confident to go ahead and experiment.

ectomorph said...

at the end of the procedure you say "For the trigger return spring and hammer spring, I recommend 12 lbs and 10 lbs, respectively"

shouldn't that be reversed ??
trigger return spring - 10lbs
hammer spring - 12lbs

Felix Estrella said...

Indeed! Nice catch! I'll fix.

Anonymous said...

Best guess is that nobody has looked at this article for awhile but thanks for the pics! I just finished my upgrade with the wilson springs 8/10 so that proves that ANY idiot can do this!

Anonymous said...

I am wondering how you get the hammer spring back on the hammer strut. Do you hold the strut in place with a vise? and how do you compress the hammer spring so that it doesn't get away?

Felix Estrella said...

I take it you didn't use the toothpick, as I instructed. Bad student. Two demerits.

Anonymous said...

I used the toothpick to remove the stock hammer spring, but how do I get the new one to compress on the hammer strut?

bvandeuson said...

I must have gotten a GP that QC missed. The trigger pull SA and DA are flawless, smooth, and no creep, right out of the box. If I put in a set of Wolff springs, it should be unreal.
All I've done to it was mount a Redhawk red front sight and remodel the hammer spur to a target configuration. The Redhawk sight blade fits the GP, but it is taller, about 1/10", which has to be removed to restore the original sight alignment.

robert said...

how do you get the trigger return spring out of the trigger module?

Bob WO3B said...

Load the spring with a kitchen fork until you can get it down far enough to put your pin/toothpick back in place.

Unknown said...

That's a good tip. Thank you!