Revolver-Double action only?


January 9, 2005, 06:56 PM
I see that some gunsmiths will convert a double-action revolver to double action only. Is that a good idea or a bad idea? is it reversable? Does it make sense to do if you have the hammer bobbed?



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January 9, 2005, 07:08 PM
If you use it just for defense it's ok, just like the DAO autos. They modify a part.To return it to normal use a part would have to be replaced. A bobbed hammer helps drawing from conceled carry but you reduce the weight of the hammer and I worry about reduced strike on the primer .I always place my thumb on the hammer as I draw it anyway.

Old Fuff
January 9, 2005, 07:51 PM
Boy, you is full of questions .... :D

1. If you carry a revolver concealed and covered by clothing (shirt, coat, etc.) you don't want anything - and I do mean anything - that may snag or catch on whatever you're wearing. At a critical time your draw may become an "almost draw," and that can have serious consequences. The available options are:

A gun with a covered hammer (sometimes called a "hammerless" revolver). But the models 13/65 do not fall into this category.

A similar gun with a shrouded hammer. It is unlikely to snag, but can still be thumb-cocked. Again the models 13/65 don't fit.

A conventional revolver that has had the hammer spur removed (sometimes called "bobbing,") which you can do to a model 13/65.

2. After de-spurring a hammer it is advisable to make it work in the DAO mode because it can be tricky to lower the hammer on a loaded chamber without a thumb-spur. It can be done, but in my opinion it is a foolish risk. Other will disagree with me so you'll have to make up your own mind.

In addition, under the stress of a potential shooting situation you may unintentionally fire a revolver that has the hammer cocked. This happened often enough so that several large police departments and federal agencies either had their present revolvers converted to DAO or ordered new guns that came in this configruation. When they changed to automatics they ordered them with some sort of DAO trigger pull or with a simulated DAO trigger pull (Glock being the prime example).

As I previously pointed out on another thread, if you subsitute a different hammer that has been bobbed you can reverse the process by reinstalling the original hammer. the DAO modifications require that the hammer be changed, but not necessarily any other parts. So long as the springs are not fooled with ignition will remain reliable - this was proven by the many law enforcement agencies and departments that used modified-to-DAO revolvers before changing to pistols.

Accurate double-action shooting is perhaps more difficult then the single-action method. But it can be mastered. That part will be up to you. One of the strong points of the older S&W K-frame revolvers is that they have - or can have - exceptionally smooth double-action trigger pulls.

January 9, 2005, 08:45 PM
Fortunately for me Old Fuff, you have the answers.

Thanks again.


January 9, 2005, 09:03 PM
Fuff, as ever, has covered this admirably Dick.

I am only adding re an example of one of my pieces, outa interest. M28-2 which was radically reworked by another owner. Hammer was bobbed, trigger smoothed to better than butter - and chambers chamfered. It may be an N frame but is 4" and very carryable, this time of year in particular. The addition of CT grips also makes it even more versatile.

All the bobbing has done is make it D/A only - tho S/A is there, if t'were safe and practicable - which it ain't! For defensive use IMO D/A is ONLY function required and as such requires practice in that mode. On this gun I did tweak up the leaf main spring just a hair to ensure totally reliable strikes ... it may have added a half ounce or even more to the pull - but when we are talking better than butter - no biggie at all.

January 9, 2005, 09:19 PM
Making a Smith DAO is as simple as a couple swipes with a file. The SA sear needs to be taken off, I did both the hammer and the trigger though you can just do one or the other. Clean it off with a file, then stone it smooth. I have a bobbed hammer and DAO hammer set that works great in my 15 and 19.

This set would live permanently in my 19 if it weren't for the fact that my holsters are all thumb-break types. I need to find another holster that offers positive retention without a thumb-break, then I will keep it in.

DAO is the only way I shoot so it isn't a big deal to me.

For bobbed hammers with SA capability Fuff has a good point, letting that sucker down is HAIRY and SCARY. You can checker the top and sides of the hammer and that is the ONLY way I would consider a bobbed hammer that still had DA capability.

Old Fuff
January 9, 2005, 09:54 PM
Trying to file S&W's case hardened lockwork is a good way to ruin the file, and isn't necessary.

If a hardened tool-steel pin is inserted inside the rebound slide spring and CAREFULLY trimmed to length it will stop the trigger's travel at a point after the hammer is released in the double-action mode, but before the trigger's rotated far enough to engage the full-cock notch in the hammer. Removing any metal on the hammer's lower engaging surfaces must be done with great care because some of those surfaces are relative to the double-action pull and any improper modifications can cause serious complications.

January 10, 2005, 09:44 AM
Good trick with the pin. With it fitting the spring well and a nice chamfer it woudn't hang on the coils either. I will have to try that.

Old Fuff
January 10, 2005, 10:55 AM
See …. You no-good, so-and-so’s have tricked the poor Old Fuff into revealing one of his deepest secrets. But then it’s well known that he’s pretty easy. :neener: :D :D

The trick works, but you can save some time if you use a piece of soft rod stock (even a nail if it’s the right size) to make a pattern. The pin should be an easy slip fit inside the spring (spring inside diameter’s can vary) and the final pin should be hard and polished. If one doesn’t have a selection of pin stock (available from Brownells at: they can select a twist drill of the right size and cut off the shank.

Start with the pattern-pin and cut it so you can see about 1/8” inch sticking out at the front of the slot in the rebound slide. This should be too long, and the trigger won’t move nearly far enough. But as you SLOWLY AND CAREFULLY trim the pin you’ll get to where you want too be. If you reassemble the lockwork without the hand you can better see what you are doing and what going on. Do have a magnifying glass handy. You will probably end up making several pattern-pins but when one is right, measure the length and you’re set to go in making the real part.

I have on occasion installed a pin to block the hammer’s rearward travel, but this involved drilling a hole in the frame and sideplate, and I decided it was a good case of overkill, being neither necessary nor desirable.

S&W has used a similar method to make a single-action trigger stop in some N-frame revolvers, but it is generally worthless because they don’t (or didn’t) take the time to get the length right.

One side benefit of the rebound slide pin arrangement is that it reduces or eliminates the problem some have of their finger being pinched between the back of the trigger and the trigger guard. Last but not least, no irreversible changes have been made to the gun that you can’t easily undo if you want to.

If one isn't sure about the concept of D.A.O. and a bobbed hammer they can install the pin as described to in effect block the single-action and try it out for awhile. Then and only then go the rest of the way and cut off the hammer spur (or replace the hammer with a bobbed one) if that's what they still want.

I strongly recommend that those who want to do any "homesmithing" or simply service a S&W revolver obtain a copy of Jerry Kuhnhausen's "The S&W Revolver - A Shop Manual," that is also available from Brownells. This book will pay for itself in preventing the mistakes that you don't make. :eek:

January 10, 2005, 11:08 AM
This poor M15 was pretty beat up, but saved. It's now DAO. The trigger pull on the S&W is very nice which makes accurate DAO pretty easy.

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