GP100 hammer bobbing

[Fishbreath]

I bought a GP100 hammer on eBay just now, since I've been wanting to experiment with bobbing or otherwise lightening one without the risk of ruining the only hammer I have. Before I embark on any actual cutting, I wanted to check in with the brain trust here to see what gotchas there are.

 

I had a few specific questions, but I'll happily listen to advice beyond them, too.

 

1. Ruger says the hammer's a fitted part. Is there actually serious fitting to do to swap a new hammer in?

2. I'd kind of like to keep an abbreviated spur as a safety blanket, even if I almost never use it. So, rather than knock the spur all the way off, I'm thinking of taking about half of it off and undercutting it some, possibly both below and above the spur. (A little like this, but more aggressively, and above the spur too.) Is there any sense to that plan, or should I just bite the bullet (so to speak) and lop the whole spur off?

3. How much lightening is worthwhile, and how far is too much? Most of the pictures of bobbed Ruger hammers look like this one, which this  show the spur taken off but few other changes. Is there any value in going lighter than that, or any serious risk in it? My main goal is to get to 100% reliable ignition with the 9lb hammer spring I have in now, and free myself to experiment with clipped coils on a spare.

4. What tools are adequate for grinding? I have plenty of dremel cutoff wheels, but for shaping, I assume I'll need something more than the sandpaper wheels that came with my dremel. Should I be looking at tungsten carbide grinding bits?

 

Thanks!

Edited January 31, 2021 by Fishbreath

[PatJones]

Why do you feel a need to leave a shortened hammer spur? I feel that single action functionality on a bobbed hammer is unsafe. If I bob a hammer, I remove the cocking notch with a stone.

 

Did your new hammer include a new hammer dog (double action sear)?

 

I do the final shaping of the bobbed hammer with a bench mounted belt grinder. Dremel tools are useful for making additional work for gunsmiths.

[perttime]

If you are going to leave the hammer spur on, I'd consider shortening it just a little. Insted, you can make it rounded and tapered. Also, take out some of the checkering. At least on mine, the edges were sharp enough to draw blood.

[IHAVEGAS]

A revolver smith friend of mine attempted to quantify the value of bobbing the hammer on his smith. His conclusion was that the value was real but subtle,  I am not sure the o.p. Will achieve his goal. 

 

I have not done it, but have read about removing some material on the face of the hammer to improve ignition on GP100s others might know details.

 

If it was me I would send the hammer to Dave Olhasso or tk custom or etc and ask them to do a full competition cut. Even with no spur you can manually cock the hammer for group shooting if desired.

 

Based on my 2 rugers it is hard to see much hammer fitting, particularly because those guns use shims to get the hammer to frame clearance right. 

 

Good luck. Anxious to see what reliable pull weights can be achieved. 

 

 

[Fishbreath]

 

8 hours ago, PatJones said:

I feel that single action functionality on a bobbed hammer is unsafe.

 

I certainly don't want to be unsafe. Could you expand a little? Is it just about losing grip on the hammer while attempting to use it SA, or is there more to it?

 

8 hours ago, PatJones said:

Did your new hammer include a new hammer dog (double action sear)?

 

Yup, along with some other miscellaneous small parts (pivot pin, mainspring strut and seat).

 

7 hours ago, perttime said:

If you are going to leave the hammer spur on, I'd consider shortening it just a little. Insted, you can make it rounded and tapered. Also, take out some of the checkering. At least on mine, the edges were sharp enough to draw blood.

 

I'm getting the sense from you and Pat that I should take the spur all the way off, if I'm going to try it.

 

24 minutes ago, IHAVEGAS said:

If it was me I would send the hammer to Dave Olhasso or tk custom or etc and ask them to do a full competition cut. Even with no spur you can manually cock the hammer for group shooting if desired.

 

Based on my 2 rugers it is hard to see much hammer fitting, particularly because those guns use shims to get the hammer to frame clearance right. 

 

I'm satisfied with the work that Dave did on my cylinder, and shipping a hammer's certainly cheaper than shipping a gun, so it's definitely worth it to get a quote, at least.

 

Thanks for the note on fitting. I too am hoping to see if I can get the Ruger down into the 6-7lb range—I'm pretty solidly in the 7-8lb range now.

 

Apparently at least one smith does/did skeletonized hammers like TK has for Smiths, which are kind of neat, but well beyond my home machine shop.

 

[IHAVEGAS]

12 minutes ago, Fishbreath said:

certainly don't want to be unsafe. Could you expand a little? Is it just about losing grip on the hammer while attempting to use it SA, or is there more to it?

 

Might be brand specific? The GP100's hammer safety provisions seem very robust and seem to have been designed with a thumb slipping off the hammer in mind. Without the spur it is easier to slip and let the hammer drop but it seems like manufacturers would need to be aware that even with the spur folks can slip and let the hammer drop (gloves - cold hands - etc.) and make suitable safety provisions. 

[PatJones]

1 hour ago, Fishbreath said:

 

 

I certainly don't want to be unsafe. Could you expand a little? Is it just about losing grip on the hammer while attempting to use it SA, or is there more to it?

 

 

Yup, along with some other miscellaneous small parts (pivot pin, mainspring strut and seat).

 

 

I'm getting the sense from you and Pat that I should take the spur all the way off, if I'm going to try it.

 

 

I'm satisfied with the work that Dave did on my cylinder, and shipping a hammer's certainly cheaper than shipping a gun, so it's definitely worth it to get a quote, at least.

 

Thanks for the note on fitting. I too am hoping to see if I can get the Ruger down into the 6-7lb range—I'm pretty solidly in the 7-8lb range now.

 

Apparently at least one smith does/did skeletonized hammers like TK has for Smiths, which are kind of neat, but well beyond my home machine shop.

 

 

1 hour ago, Fishbreath said:

I certainly don't want to be unsafe. Could you expand a little? Is it just about losing grip on the hammer while attempting to use it SA, or is there more to it?

If the revolver is cocked and want to lower the hammer, you would have diminished control while doing it. None of the drop safeties would help you as you need to pull the trigger to drop hammer.

 

I don't use the single action on my double action revolvers, I'm not a cowboy.

[IHAVEGAS]

On 1/31/2021 at 9:28 AM, PatJones said:

If the revolver is cocked and want to lower the hammer, you would have diminished control while doing it. None of the drop safeties would help you as you need to pull the trigger to drop hammer.

 

Grab hammer, pull trigger so sear releases hammer, as soon as hammer is released let off the trigger. Some folks place their finger between hammer and frame and just roll the finger out after releasing the trigger.

Those of us that shoot d.a. / s.a. production guns do something similar on every stage at USPSA or IDPA matches, it is a bit more dicey with those guns as you have to keep the trigger pulled so you clear the half cocked notch.

[MikeyScuba]

While I only shot my wife’s SD2 once at a match last Dec  pulling the trigger and dropping the hammer during LAMR freaked me out.  Well not exactly but I didn’t like it one bit.  I’ll take my revo or 2011 any day.

[PatJones]

11 hours ago, IHAVEGAS said:

 

Grab hammer, pull trigger so sear releases hammer, as soon as hammer is released let off the trigger. Some folks place their finger between hammer and frame and just roll the finger out after releasing the trigger.

Those of us that shoot d.a. / s.a. production guns do something similar on every stage at USPSA or IDPA matches, it is a bit more dicey with those guns as you have to keep the trigger pulled so you clear the half cocked notch.

I stand by my opinion that doing all of this with a partially removed hammer spur diminishes the level of safety involved.

[IHAVEGAS]

49 minutes ago, PatJones said:

I stand by my opinion that doing all of this with a partially removed hammer spur diminishes the level of safety involved.

 

And that is a perfectly reasonable opinion. It is something that I am fine with,  but I know from shooting my production gun and hearing the occasional comment that there are other folks that share your concern. 

[pskys2]

Personally do one or the other.  If you want that final 'nth' take it off, take it all off.  If you want the option of a SA shot, leave it alone it's not going to make as much difference as dry firing, or shooting, 10,000 times.  Unless you have a super high hold, or huge paws, that the hammer hits the web of your hand, then "off with their...spurs".

[Fishbreath]

1 hour ago, pskys2 said:

Personally do one or the other.

 

I think I'm pretty much resolved to do that now—the whole point of having two hammers is so that I can do irreversible things to one of them, without worrying about not being able to go back.

[pskys2]

20 hours ago, Fishbreath said:

 

I think I'm pretty much resolved to do that now—the whole point of having two hammers is so that I can do irreversible things to one of them, without worrying about not being able to go back.

Been there done that!

[Fishbreath]

It turns out (he says, with egg on his face) that the Super GP100 doesn't actually use a GP100 hammer. It looks like it might be a Super Redhawk hammer instead—it's slightly longer than the GP100 hammer I bought.

 

I guess I'll go put up a classifieds entry in a bit.

[perttime]

Missed the Super in your posts, if it was there.

The Super is quite a hybrid. If you want to try with parts that fit, better check what actually fits. I think the frame is Redhawk (not Super), with GP100 features.

I have no idea if a Super Redhawk hammer is the right part.

[Fishbreath]

I guess 'super' wasn't in my earlier posts. Oops.

 

Anyway, the Super Redhawk hammer at least looks like the Super GP100 hammer (whereas the Redhawk hammer doesn't, with the different mainspring attachment), but I guess I wouldn't be entirely surprised if the Super GP100 hammer ends up being a distinct part, or some hybrid between the Redhawk size and GP/SRH parts.

 

Luckily, I don't mind spending a little money on experimentation. I found a Super Redhawk hammer at a good price, and will try that and report back.

[Fishbreath]

It does appear that the Super Redhawk hammer is a functional replacement part for the Super GP100—it functions correctly in single and double action, pushes the firing pin forward when the transfer bar is in place, and doesn't interact with the firing pin when it isn't.

[Fishbreath]

Did the bobbing work last night. Looks to have come out pretty well.

 

 

The surface finish isn't great, because I didn't have much in my arsenal in between grinding wheels and 1000-grit sandpaper, but I achieved what I wanted to do shape-wise—a bit of an undercut below where the spur used to be in an effort to keep the tip-heavy weight distribution, and a smooth transition from the curved sides at the top to the sharp corners at the lower body. A carbide grinding bit for the Dremel helped dramatically with shaping after I removed the spur.

 

I did some investigation with my cell phone in 240fps slow motion mode, and if there's a difference in lock time, it's quite small. With both my stock hammer and this one, the hammer takes four frames between the start of its movement and its first contact with the revolver's frame: about 16 milliseconds. Can't speak to ignition yet, but I have some ammunition earmarked for testing (as opposed to practice) in March.

 

This hammer actually fits my frame better than the stock one does (was able to step down from 0.016" of shims to 0.014", with less side-to-side play in the end). The hammer dog was looser, though, and I believe it also has 0.014" of shims.

[SSGGlock]

Sweet, looks good.

[IHAVEGAS]

17 hours ago, Fishbreath said:

 

 

—a bit of an undercut below where the spur used to be in an effort to keep the tip-heavy weight distribution,

 

Tip heavy is something new to me in competition hammers. Why did you want that?

[Fishbreath]

4 hours ago, IHAVEGAS said:

Tip heavy is something new to me in competition hammers. Why did you want that?

 

Some sources at rugerforum.net with a long post history as gunsmiths suggested it might be worth trying—something about sweet spots and wanting to keep the mass of the hammer as concentrated directly behind the firing pin as possible. I don't know if there's anything to it, but I don't have enough primers or hammers to do the science, so I figured I'd take the safer route for now.

 

There are also pictures out there of a skeletonized GP100 hammer, which I thought about trying, but I don't have the home machine shop for that yet.

[revoman]

Where did you get your hammer. Also the release has not shown  up yet in the mail 

[Fishbreath]

I found the hammer on eBay—they pop up now and then.

 

USPS says the package left Omaha yesterday, so I guess it'll be another day or two before it gets to you.

[revoman]

I know I sent a MO for an AR and it was going to Connecticut and it took like 2 weeks and I even paid for 3 day delivery. Thanks for the tip on the hammer