GP-100 hammer


walking arsenal
July 19, 2004, 04:26 PM
does anyone know if you can just swap out the hammer on a GP-100? i have a GP-100 hammerless and would like to put a normal hammer in, but i dont know if i can just drop one in or if a trip to the smith is in order. does anyone know?

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July 19, 2004, 06:16 PM
It might just drop in, but it will likely take a little fitting of the engagement surfaces to be right.

Jim March
July 19, 2004, 06:19 PM
Per my *limited* understanding, a fresh hammer will usually fit, but MAY need final "fitting" on the engagement surfaces between hammer and sear. This fit is a critical safety thing.

In your shoes, I'd score another hammer from Brownell's, throw it in and do a THOROUGH "checkout" on it. Make sure it doesn't "push off", or still stays cocked when prodded/wiggled. Make sure the firing pin's protrusion is enough.

-=ANY=- questions on it after that means gunsmith time. Do not pass go, do not collect $200, get it in to the gun veterinarian el mucho pronto.

IF THE HAMMER CAN BE COCKED AT ALL (still has the "SA notch", which many do): It occurs to me that there may be a funky alternative. Drill two holes sideways through the back "curve" of the hammer you have now, and carve a solid brass or aluminum "thumbrest" which saddles over the back of the hammer and it attached with crosspins. Odd? Sure. But it would allow you to set the hammer thumbpad height and ergonomics to whatever you wanted, and if it broke...well, it's still going to work in DA mode regardless in a pinch.

July 19, 2004, 08:24 PM
Walking . . .

Jim March is an expert and I am a novice, so I hate to disagree with him. I remember reading, however, that you could NOT simply substitute a normal, spurred hammer in a hammerless/spurless Ruger SP-101. While I do not remember the details, it had nothing to do with the alternate hammer's fit, rather with some other part in the "firing chain".

Now I want to make three points very clear: (a) I only read this, I have no hands-on experience with it, (b) I am assuming the SP-101 information is correct (it may not be), plus (c) I am presuming the fundamental design of the SP-101 and the GP-100 are extremely similar.

I am not certain any of the above premises are correct, but I want to pass along this information, with the foregoing caveats. You may want to check the TFL and THR archives to ascertain complete details.

July 19, 2004, 09:12 PM
I have just been through this so I got some good intel on the matter.

If you have one of the French Police surplus GP-100s with the DA only trigger, it can not be swapped out for a normal spurred hammer. I assume you do have this gun as they are floating around right now. If yours is a half shroud bbl, that is most likely what you have. Ruger will not sell you the hammer because it may be unsafe as Mr. March explained. It can be made into a DA/SA revolver again but it needs other parts than just the hammer. I am pretty sure on this but I never did swap out my DAO hammer with a normal hammer. I wanted to but when I found out that I would need more parts than just the hammer, I decided to make my 4" GP-100 into a 2 1/2" snubby. I love it as a monster snubby and it still shoots well. Recoil is mild even with full house .357 mags and I keep it as my car gun. Many times I felt better knowing that I had it in my glove box instead of my Berettta 21A. That was my old car gun and there is a big difference between the two. :D

walking arsenal
July 19, 2004, 11:10 PM

You would be correct, this is indeed a french version (never been fired?) im guessing from your post that i may have to do the trigger group as well. my next question is can i buy a trigger group and hammer and have them fitted to the frame? maybe a new weapon is in order, the trigger pull isnt real heavy but i can only get a box or two of shells through it before i cant do the double action pull anymore. single action would be a nice option.

Jim March
July 19, 2004, 11:25 PM
Interesting. Very. Hmmm :).

July 20, 2004, 05:30 AM
Could the extra needed parts be the DA sear, spring, pin, and possibly plunger?

July 20, 2004, 10:47 AM
Why all the speculation, why not call Ruger. My speculation is that they will tell you that the gun needs to be sent in and fitted with the necessary parts.

July 20, 2004, 04:48 PM
Why all the speculation
Because so many of us would rather do the work ourselves. Why ship a gun to the factory for work you can do yourself?

July 20, 2004, 08:17 PM
Ruger may not do the work for you because they have a silly rule about not changing the action from what it was made at the factory. I called and asked if I could send it in and have them fit the parts needed to make it a regular DA/SA gun and they said they would not do that work because it would be changing the action.

If you are really unhappy with the gun as is, I suggest trading it or selling it and getting something that you like better. Everyone makes mistakes on gun purchases. I did the same thing when I bought mine. The guy that sold it to me said he had extra hammer that he could sell to me for $20 but after I bought it, all of a sudden, he couldn't come up with them.:rolleyes: I had no use for a DAO 4" GP-100 so I turned it into the snubby that I told you about. I will post a pic or a link so you can see it.

July 20, 2004, 08:21 PM
Here is the link to my snubby GP-100. I am really happy with it now.

walking arsenal
July 20, 2004, 08:34 PM
thats really nice. how much did it cost you to get it done?

July 20, 2004, 11:23 PM
Nothing. I did all the work myself. If I had to add up my time at what I make, it would have cost a lot more than just paying a gunsmith to do it. The thing is, it was a lot more fun to work on that gun than to work at my job so I don't think of it in those terms.:D

I'm no gunsmith but I have found if I go slow and take all the time I need, I can often do what I intend to do. If I had access to more and better tools, I would consider doing some other projects. All I have is basic home garage tools so it takes me longer to do anything. I don't even have a vise.:(

July 21, 2004, 10:30 AM
I bought a 4" half shroud, DA GP-100 at a gunshow about two or three months ago. The dealer at the show said they were Royal Canadian Mounted Police turn-ins. By serial number, manufactured sometime after 1989, I think. At least I didn't by the magic beans some teary eyed kid was selling. I too had thought about conversion to SA/DA but just as a thought. It's a good bedside HD gun but my S&W 637 is my "always' gun.

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