Why do people do this?

[Twiki357]

I have a number of S&W “J” frame revolvers that I have purchased used. Three of them have what I would call “Semi” bobbed hammers, not the whole hammer spur, just part of the knurled portion. I understand the reason for a fully bobbed hammer to avoid snagging, but I just don’t see the logic behind removing just a portion of the knurled thumb spur. So why do people do this? Is it just to minimize potential snagging without eliminated the single action capability, or what?

Ironically, when I searched for J frame hammers on ebay looking for a replacement, all the ones that came up were ones that had the hammer spur mutilated in the same way.

 

[Monac]

For a considerable time in the 1980's, IIRC, Smith & Wesson did not make the Centennial hammerless J-frame 38, and the Bodyguard shrouded-hammer version was in short supply. Getting the hammer bobbed by a gunsmith was probably a cheaper way to get something similar. Are these guns very old?

 

[Twiki357]

The three of them have shipping dates of 1973 purchased last month, 1977 purchased in Aug 2013, & 1982 purchased in May 2012, so they are all over 30 years old. My curiosity just came to a head with the one I just got because the knurl was reduced to the point that what’s left is like a razor blade.

That would fit with your explanation about the 1980’s.

 

[WardenWolf]

Also because some models of J-Frame have a tendency to bite the webbing of your hand in double action if you let your hand ride too high. Modifying the hammer can prevent this.

 

[Barry the Bear]

Its easier to modify the gun you have, then wish for the one you dont.

 

[WestKentucky]

Carrying iwb, often times on bigger folks (me) when sitting down the gun starts digging into the gut unless it has a very very well built holster or has the hammer spur modified. On j frames I have seen what you are mentioning and it seems to be an effort to combat this pain while also trying to retain full functionality.

 

[BobWright]

Many shooters use a very high grip on their revolvers, and a semi-bobbed hammer will not dig into the flesh of the hand when firing.

Bob Wright

 

[Old Fuff]

Also some worried that ignition might be affected if the hammer's weight was reduced too far. This would be especially true if a lighter or cut hammer (main) spring was part of the picture.

I would advise anyone buying a sub-compact (J-frame size) revolver with a fully or partly bobbed hammer check it over carefully - or have a qualified gunsmith do the same - to determine exactly what was done, if anything, besides modifying the cocking spur.

 

[CZ9shooter]

I took about an eigth of an inch off of mine. It had the tendancy to find its way to the web between my thumb and index finger. Not a big deal, but I didnt like. It should be less prone to snagging now too. The spur used to be long and slender. I gave it a more blunt round end. It looks more appealing to my eye the way it is now.

 

[Drail]

The weight of the hammer is not a factor in popping a primer. With a normal weight mainspring a hammer that has been cut down to a fraction of its original weight actually moves faster and delivers more energy to the primer. reduces the lock time, and does not jar the gun as much. People have been doing this for many years. The mainspring is what provides all of the force to light a primer - reducing the hammer's mass does not change that (unless you ADD so much mass that the mainspring cannot accelerate the hammer up to speed before it hits the firing pin). People do love to cut mainsprings down though to lighten the DA pull. I have a few revolvers and 1911s set up for USPSA/IPSC shooting that had the hammers cut to a thin sliver of their factory dimensions and never had one fail to pop a primer with a standard power mainspring. I have race guns set up with very light springs and radically bobbed hammers - but I would not do that on a carry gun. All of my carry guns use full power mainsprings. For a long time DA revolver hammers were bobbed halfway just so you could manually cock and decock them (carefully) if you absolutely needed to make a single action shot for some reason. But to me the proper way to shoot a DA revolver - is in DA. On any used revolver I buy the first thing done is to clean, inspect and replace ALL of the springs to new factory power. Unless this is done your gun may be right on the edge of failing to function (usually when you really need it to work).

 

[leadcounsel]

I have a number of S&W “J” frame revolvers that I have purchased used. Three of them have what I would call “Semi” bobbed hammers, not the whole hammer spur, just part of the knurled portion. I understand the reason for a fully bobbed hammer to avoid snagging, but I just don’t see the logic behind removing just a portion of the knurled thumb spur. So why do people do this? Is it just to minimize potential snagging without eliminated the single action capability, or what?

Ironically, when I searched for J frame hammers on ebay looking for a replacement, all the ones that came up were ones that had the hammer spur mutilated in the same way.

Can the answer really be the obvious... you can grind down and polish a hammer in a few moments and it costs nothing. Replacing a hammer requires ordering it, paying for it, taking the gun apart, replacing it, and re-assembling it... and you're left with a spare part you neither want or need. The nub keeps the integrity of the hammer without risking cutting grinding too deep to sacrifice strength, and offers some purchase but reduces snagging.

A new hammer costs, what, $30. So you're griping about having to find a new one, pay for it and replace it... I'm willing to bet the original owners had the exact same thought in reverse, and just took it to the grinder. Many people care for function over form...

 

[MrBorland]

The weight of the hammer is not a factor in popping a primer. With a normal weight mainspring a hammer that has been cut down to a fraction of its original weight actually moves faster and delivers more energy to the primer. reduces the lock time, and does not jar the gun as much. People have been doing this for many years. The mainspring is what provides all of the force to light a primer - reducing the hammer's mass does not change that

Sort of.

The mainspring provides the energy. The hammer merely transfers it, so energy doesn't increase if you lighten the hammer. And energy doesn't pop primers; if it did, merely resting a hammer on a live round would set it off, no matter how slowly you lowered it. What sets off primers is power, and power is essentially the product of energy and speed.

A lighter hammer with a stock mainspring travels faster, so it delivers more power upon primer strike. As such, you can reduce mainspring tension (to a point) without loss of reliability if you also lighten the hammer.

As a bonus, as you mentioned, the lighter hammer jars the muzzle less since it has less momentum.

It's all akin to a car rolling along at low speed when tapping you from behind. It'll jar your entire car (lots of momentum), but won't damage to your bumper (low power). In contrast, taking a good whack at the bumper with a hammer (same energy) will certainly dent the bumper (lots of power), though the car won't budge (low momentum).

 

[BobWright]

leadcounsel said:

................. Replacing a hammer requires ordering it, paying for it, taking the gun apart, replacing it, and re-assembling it... and you're left with a spare part you neither want or need. .......

Replacing the hammer is not exactly rocket science on a revolver. And spare parts in the parts box is like cash in the pocket. Someone is always looking for a barrel, cylinder, trigger, hammer, whatever. Always good to have on hand, for either cash or trade goods.

And, who knows, you may want to put the gun back in original condition one day.

Bob Wright

 

[Old Fuff]

Replacing the hammer is not exactly rocket science on a revolver.

Sometimes - it depends on the revolver. Smith & Wesson hammer's often, but not always interchange. The greater issue is the sear (the little lever mounted in the face of the hammer) that is (or was) individually fit to each gun.

This, and for other reasons is why I recommended returning the gun to S&W if it is still under warrantee. If any parts have to be replaced it will be on their dime - unless the original ones were altered outside of the factory.

If the hammer has been altered they won't fix it under warrantee, but a new one will be correctly fitted.

And if the hammer in question is a pre-MIM, the cost these days is likely to be closer to $50.00.

 

[herrwalther]

They want the best of all the worlds. They want DA/SA but not the *possability* of a hammer snagging on clothes during the draw. This is especially true of J frame sized revolvers for pocket carry. So they bob the hammer a bit (or a lot in some cases I have seen) to where it barely counts as being there.

 

[BCRider]

It sounds to me like those previous owners had commitment issues.....

Since it's half way done already if it were me I'd just finish the job and bob off the remaining amount.

I've found that speed is what pops primers. A light hammer traveling fast is far better than a heavier hammer moving slowly. After all many guns transfer the hammer's speed to a very small and light free floating firing pin. Obviously it needs enough inertial energy to deform the metal. But it's the speed of that deformation that sets off the priming compound.

So all else being equal removing the last of the remaining spur should enhance the reliability.

 

[Old Fuff]

How about a heavier hammer moving faster???

Example: Colt Single Action Army and copies/clones.

 

[MrBorland]

How about a heavier hammer moving faster???

Yeah, you could do that, but then you increase momentum and it's muzzle-jarring effect.

And in the case of a DA revolver, the trigger pull would be heavier, since it'd be sprung heavier to get the heavier hammer to the same speed.

Example: Colt Single Action Army and copies/clones.

To be honest, I'm not sure they're heavier. Ever weighed an example each (SA & DA hammer)? I'd be curious to know the diff.

More to the point, though, I wonder which has more inertia. Since the hammer's rotating, inertia is really more relevant than weight. We use "weight" because it's easier to measure, but "heavier" doesn't always mean "less inertia". Much depends on the shape of the hammer.

 

[Gun Master]

I have a number of S&W “J” frame revolvers that I have purchased used. Three of them have what I would call “Semi” bobbed hammers, not the whole hammer spur, just part of the knurled portion. I understand the reason for a fully bobbed hammer to avoid snagging, but I just don’t see the logic behind removing just a portion of the knurled thumb spur. So why do people do this? Is it just to minimize potential snagging without eliminated the single action capability, or what?

Ironically, when I searched for J frame hammers on ebay looking for a replacement, all the ones that came up were ones that had the hammer spur mutilated in the same way.

The reason for the bobbed (or semi- bobbed) hammer is almost always done to avoid snagging on clothing while drawing, as you stated.
I had a friend with the Border Patrol who had a S&W 1917 .45 ACP (or AutoRim) customized for off duty carry. The barrel was cut and crowned to 3", Stag grips, and hammer semi-bobbed, with a V notch on top of the hammer. This allowed you start cocking the hammer by pulling the trigger, and using the thumb nail in the V to complete SA cocking. Oh, and he had a beautiful hot blue applied to it.
I traded him my good to very good Browning Sweet Sixteen shotgun, for it. I got a very bad booty compact (but heavy) .45 ACP wheelgun.
That's all I have to say at the present.

 

[Old Fuff]

To be honest, I'm not sure they're heavier. Ever weighed an example each (SA & DA hammer)? I'd be curious to know the diff.

More to the point, though, I wonder which has more inertia. Since the hammer's rotating, inertia is really more relevant than weight. We use "weight" because it's easier to measure, but "heavier" doesn't always mean "less inertia". Much depends on the shape of the hammer.

The Old Fuff must admit that some times his warped sense of humor gets out of control.

Your observations are quite true, but if you have had much experience with the 1873 model thumb-buster you'd know that the mainspring can be reduced to ridiculous levels and the hammer will still pop caps. This is because being heavy (much more then any of the popular hand-ejector revolvers) it also travels in a wide arc. All of this was necessary when it was introduced because the primer was located inside the cartridge case.

As a sidelight: Many decades ago a San Francisco gunsmith named Bob Chow experimented with a Colt 1911 pistol, in which he started with the original wide-spur hammer introduced in 1911. He cut the spur down in steps until none remained, and discovered that ignition remained positive with the full strength main spring, but he found no perceptible increase in lock time.

Also some consideration should be given to the fact that this business of ultra-light hammers in S&W revolvers mostly came about after they took the hammer nose (firing pin) off of the hammer and moved it to the frame. This made extra long firing pins an easy option that wasn't available before.

In the old days of past (and mostly dark) times I knew another 'smith that would remove the firing pin, face a little metal of the hammer's front, and then put the firing pin back. Of course this increased the pin's protrusion. He then created some memorable double-action trigger pulls that apparently were both light and reliable - but most of his customers were bullseye target shooters who exclusively thumb-cocked.

 

[Twiki357]

I didn’t think my (I thought) simple question would generate so much response. I expected only a simple confirmation about reducing potential snagging.

It’s the number of “Semi” bobbed hammers on ebay that surprised me, especially with no hammers with a full spur and only one that was “Fully” bobbed. I was just looking for a replacement hammer with a full spur. Oh well, I guess one will show up sooner or later.

Thanks for all the logic and side notes that I hadn’t thought of. Interesting reads.

 

[CleanHarry]

Physics

I ain't no expert, but I can read. I just read that the mass of the object does play in the amount of force applied. Mass and speed. Heck, it's the same as a bullet... Big mass at high speed gives more force than small mass at high speed. Smaller mass at high speed delivers more force than small mass at lower speed.

You have potential energy when the hammer is cocked. You have kinetic energy when the hammer is in motion. A hammer sitting against a cartridge is applying much less force than a hammer applying kinetic energy at the end of its arc.

I guess you could argue that a spring would accelerate a lighter hammer to a higher speed than that same spring could accelerate a heavier hammer. Force is a function of speed and mass. It is force that pops the cap, right?

 

[BobWright]

Gun Master said:

The reason for the bobbed (or semi- bobbed) hammer is almost always done to avoid snagging on clothing while drawing, as you stated.

True for a hammer that has been bobbed and smoothed off leaving no trace of a spur. However, some shooters, especially those involved in Action Pistol (or other) contests where time is of the essence, will often leave a partial stub of a spur. They grip the gun very high on the grip frame so that part of the flesh of their shootin hand is behind the hammer spur. Trimming it down some allows the hammer to clear this part of the hand in rapid DA firing.

Bob Wright

 

[saltyyn1]

Had a model 36 worked great looked like it had a rough life. I dropped it and broke the spur off the hammer and a new hammer was $58 plus installation , grinder to smooth it dokwn was free. Wish I still had it.

 

[Geldarr]

One other possibility?

As a deviation from the well-considered discussion above, I have another reason it could have happened: someone dropped the gun on the hammer spur and it broke off. I purchased a Rossi 68 for $90 a few years back that was cosmetically challenged and had a broken off spur. A few minutes with a grinder in my Dremel and some high grit sandpaper, and it ended up "semi-bobbed."

I've since removed a little bit more of the bump (didn't remove it completely to leave a little extra meat behind the hammer nose rivet), parkerized the revolver, and replaced the horrible wooden grips with Pachmayr compacts. It looks better now that the parkerizing has aged a few years; it has that nice greenish tint now. I've named it "Roscoe," by the way...



EDIT- Whoops, post above me beat me to it (by a day, no less).