Converting revolvers to double-action only

In the comments on the Super Security Six post, a couple of people have asked why I’d convert the gun to a true DAO wheelgun. For the purposes of this post I’m only going to talk about revolvers used for self-defense and competition; large caliber magnum revolvers used for hunting are excluded.

Ruger GP100 bobbed hammer

For a competition/defensive revolver there are number of considerable benefits to having the hammer bobbed and the gun converted to DAO. The first thing to note is that single action is basically worthless in competition, and is also pretty worthless in a defensive gun. You absolutely need to be able to shoot your revolver in DA if you’re going to fight with it, or if you’re going to compete with it. So since you’ll never use the SA function on your gun, you can simply delete it.

There are a couple of sound reasons for deleting the SA function of a competition/defensive gun. The first advantage is eliminating hammer bite. I have large hands, so when I’m gripping a revo I get as high as possible on the backstrap. With the hammer on a gun, I can actually bite my hand during DA shooting. Eliminating the spur eliminates that problem entirely. Once you’ve bobbed the hammer, you can then eliminate the SA notch on the gun entirely. This actually smooths out the DA pull a little bit more. It’s not a huge difference, but once the hammer spur is deleted, it makes sense to convert the gun the rest of the way to gain the incremental benefit.

Another benefit of removing the DA function of the gun is an alleged increase in reliability of ignition. The theory is based on maths which I don’t completely understand, but has to do with the force imparted to the firing pin by the hammer. As I understand it, if you take two springs of equal weight (10 pounds) they’re using that energy to accelerate the hammer. A hammer of lighter weight will accelerate faster and to a higher speed than a heavier hammer if being driven by springs of equal weight. More hammer speed = more force hitting the firing pin. Science!

Ultimately the best reason to remove the SA function from a competition gun is to remove the temptation. Shooting your guns in single action for defense and competition is bad and creates poor habits, so just get rid of it entirely.


  1. I sucked at physics, but wouldnt the loss of force due to reduced mass in the hammer be proportional to the increase in force from the greater velocity of the hammer?

    1. IIRC, Force = mass * acceleration; so the answer to the question depends entirely on how much additional speed the hammer picks up relative to the loss of mass. Which is where the math gets trickier than I’m interested in.

  2. So what we got here is, a tiny TINY increase in smoothness, an a theoretical increase in primer reliability. So if you arent getting hammer bite…. not much reason to go thru the trouble eh? Unless of couse the hammer is jabbin you in the giblets while you carry the gun, which in my opinion is reason enough.

    1. And you get rid of possible source of draw snags, especally for J frames. I bobbed the hammer of my 36 for this reason.

      1. That is an excellent point. One that should have been mentioned in the article imo.

        1. Honestly, that didn’t even occur to me. Mostly because I don’t have hammer spurs on my guns, so I’ve never dealt with it.

  3. You need to edit the reference to “DA” at the beginning of the third paragraph. You presumably meant to write “SA”.

  4. I bobbed the hammer on my SW 442 it’s awesome now. Will probably win the Bianchi Cup with it someday.

  5. Your math is bad. A 10 lb spring provides 10 lbs of force. It will impart 10 lbs on a slow-moving, heavy hammer (which would have 10 lbs of imparted momentum) just as it would impart 10 lbs of momentum on a light, fast hammer. The end result in either case is 10 lbs of force imparted to the primer.

    The bigger reason to remove the hammer spur on a defensive revolver is to prevent a plaintiff from ever claiming that you had an intent to fire before you could have identified a proper target. (“Ladies and gentlemen, Caleb was out looking to KILL ANYONE at a moment’s notice, not just prevent a threat.”)

  6. Yep, that’s the reason a glock with a lightened striker spring won’t detonate primers as effectively unless the striker itself has been lightened (hogged out with a dremel or replaced by a titanium unit). Thanks for clearing up my questions Caleb.

    1. That was actually what got me thinking about this with revolvers – I had that issue with a Glock, and then I radically lightened the striker and it went away.

      So, the maths as I understand them are that the spring uses its energy to accelerate the hammer; a lighter hammer will accelerate quicker meaning it has more energy to strike the firing pin. S&W revolver guru Mike Carmoney espoused this same theory with his incredible hammer bob, or Carmonize that he used to be perform.

  7. I figure you are talking about tactical competition here, but I just thought I would mention that in NRA Bullseye competition, the single action feature is still desired.

  8. Thankfully I had a Sig 226 SA and DA only problem is Mrs Clinton called NYC police murderers (Before she told Janet Reno kill as many people as possible on Ruby Ridge and Waco Texas) The NYC police shot at Mr. Diallo 41 times and managed to hit a non moving citizen 19 times less then 12 feet away .

    The problem I see at the range is NYC police with the semi auto’s forget to let the trigger go and “shoot for effect” meaning keep shooting until the firearm is empty and the subject offers no possible way to fire back according to a police captain and highly decorated dectective who were kind enough to give me some training with point and shoot

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