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Ruger GP100 DIY Upgrade

Ruger GP100 DIY Upgrade

As soon as Ruger introduced the GP100 in .44 Special, I bought one. A five-shot revolver with a three-inch barrel, I find it an excellent field gun—not heavy like my five-inch S&W .44 Magnum but with plenty of punch. I’ve shot it a ton, both at the range and on the set of “Handguns & Defensive Weapons,” and it’s well-behaved and accurate.

But I love to tinker with things, even though I’m not particularly good at it. One day the notion popped into my head to install different grips on it, just for something to do.

I settled on Altamont. The company offers both full-size and compact grips for the GP100, and since I already knew what the full-size grips felt like, I figured it would be interesting to see how smaller grips affected how the gun handled. I chose the compact snakeskin combo, which consists of a rubber grip and rosewood “snakeskin” inserts. Cost was $44, plus $6 shipping.

Part two involved the springs. The trigger pull on the gun wasn’t bad at all, but one day I was surfing the Wilson Combat website while fact-checking an article. I stumbled on the company’s Custom-Tune spring kits for the GP100 (just $10 plus $6 shipping), and I ordered one.

Ruger GP100 DIY Upgrade
Replacing the grips was easy. Remove the “foot” (lower l.) to enable the new grip to slide on. Install the Altamont’s locator pin through the rubber portion and pop in the wood inserts.

All of what follows starts with an unloaded gun, of course. Changing the grips is a breeze. This version of the GP100 has a synthetic one-piece grip that’s secured by a screw at the base. Remove the screw and the grip pops off. The screw threads into a swinging foot at the base of the frame (which, I discovered, is part of Hogue’s patent for a one-piece handgun grip). The foot is easily removed by sliding a fingernail underneath the spring clip and lifting it off the cylinder that supports the foot.

Remove the locator pin in the base of the Altamont grips by first popping off the rosewood inserts and then pushing out the pin. Slide the rubber grip onto the frame, run the locator pin through the holes in the grip and in the revolver frame, replace the wood inserts and use one of the supplied screws to secure the grips. Easy peasy.

On to the spring kit. Look, if Ruger’s designers thought lighter springs would be better for the GP100, they would’ve used them. But they need to ensure the gun is 100 percent reliable with any appropriate ammo, and the springs are correspondingly strong—producing a heavier double-action pull than people like me care for. Anyway, my larger point is you undertake the spring project at your own risk because you’re going to void the warranty on your gun.

Ruger does an excellent job of describing the disassembly and reassembly processes you’ll need for the job, and even I was able to accomplish them without too much trouble. If you no longer have your manual, you can download it at—and of course there are multiple YouTube videos explaining these procedures.

Replacing the mainspring is super easy. Ruger supplies a disassembly pin in the grip, but if you’ve lost it, a small punch or Allen wrench will do. Cock the hammer, stick the pin or tool in the hole at the bottom of the hammer strut, trapping the spring and allowing that assembly to be removed. (Do yourself a favor here: Grab your phone and take a picture showing the position of the strut and seat, and how they sit in the frame.)

Ruger GP100 DIY Upgrade
To replace the mainspring, remove the grips, cock the hammer and insert a tool of some sort to trap the spring. Then simply withdraw it from the frame. The Wilson kit comes with several different weight springs to try.

The Wilson kit comes with mainsprings of eight, 10 and 12 pounds. Ruger uses a 12-pound spring in the GP100, and I replaced it with Wilson’s 10-pounder.

To replace the trigger return spring, after removing the mainspring you have to remove the hammer and the trigger guard assembly. Again, Ruger’s directions are solid.

The only difficulty I encountered was one mentioned in the manual. The trigger guard lock plunger on my gun was stubborn. I had to place the revolver in a padded vise (padded!), and tap on the plunger lightly with a punch and small hammer.


That budged it and allowed me to swing out the trigger guard assembly. To replace the spring, drive out the small pin at the back of the assembly, remove the plunger. The spring is in there. Wilson also gives you choices—eight, nine and 10 pounds—and I went with the 10-pound spring in this case, too.

Ruger GP100 DIY Upgrade
To get at the trigger return spring, remove the hammer and trigger guard assembly. The spring is behind the plunger at the rear of the assembly. Drive out the small pin, remove the stock spring and install one of the new ones.

Reassemble in reverse order, ensuring that when you reinstall the trigger assembly the transfer bar and pawl are correctly positioned. Replace the mainspring assembly and the grips, and you’re done.

End result? The grips look great, fit my hand better than the originals, and they don’t detract from recoil control even though they’re smaller. And the gun is now more concealable as well.

The spring kit made a significant difference in trigger pull. With the stock springs the double-action pull was 11 pounds and the single-action pull was three pounds. With the Wilson springs aboard, the double-action pull dropped to eight pounds and the single-action pull went to two pounds, four ounces.

To test reliability, I fired 150 rounds through the gun in a single session. Loads included Remington Performance Wheelgun, SIG Elite, Hornady Critical Defense and Hornady XTP. I had just one light primer strike, which I can accept. Besides, if a round in revolver fails to fire, you just pull the trigger again.

The project wasn’t perfect, though. The Altamont grips didn’t fit completely flush on the right side, allowing the hammer pivot pin to back out of its recess slightly. A small shim seems to have fixed this.

I’m thrilled with how the project turned out. I went from merely liking my GP100 to absolutely loving it. In double action it feels like a different gun, and the Altamont grips improved the gun’s looks and, for me, the handling. So there you go: two simple, inexpensive projects to improve a revolver.

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