Double action dimples primer - Single action OK SP101

[Bullseye]

I changed my hammer mainspring in my SP101 ( larger one in the grip ) from the factory to the Wolff 8 lb spring. I left the trigger spring alone. The standard spring is 14 lbs. I think I better go up to 10 lbs and try again.
The purchase I made was for three sets of springs. 8 10 and 12 and of course my 14 lb spring is still like new.
The revolver fires great in single action but 2 out of 5 did not fire yesterday after trying DA since the spring change. I was using 500 CCI sm pistol primers and they had a pretty decent dent in them. I was surprised they didn't fire by the amount of the dent. I fired them with SA and they went just fine.
No question really but maybe someone will have had the same issue.

 

[jdavis123]

Not an unusual problem when changing spring weights. I had a similar problem with Wolff Springs on a S&W. In order to make the revolver 100% reliable regardless of the primer type, I went back to the factory hammer spring. All is good now.

 

[Drail]

Almost any time you get a spring kit with say, 3 choices on spring weight - the one in the middle is the one you want. The 8 lb. will not be reliable in 90% of the revolvers you install it in. More often than not a Ruger will need a little more spring than a S&W. And especially so with CCI primers. They are the hardest primers you can buy. A revolver can be set up for a very light DA pull but only if you use Federal primers all the time. IF the gun needs to be able to light up anything you load into it for defense use - then leave the stock factory springs in place. It sucks -but it's just the way it is. The proper way to lighten DA pull is be removing friction on all of the bearing parts by judicious stoning and smoothing. Trying to do it with lighter springs alone very often results in an unreliable action. If you are going to carry this SP 101 then don't lighten the spring weights. I would leave the stock ones in.

 

[BCRider]

I'm not surprised at the DA vs SA issue. If you check the actual point of the break on the hammer you'll see that it does not travel back as far in DA as you set it to for SA. So it's a very slightly shorter drop in DA and a little less impact energy as a result.

So if you're getting DA dimples with no BANG then you're really on the ragged edge. Going up the one power level will likely fix it.

If you're using this as a SD gun as well as range toy then even with the next up spring I would not trust it with your life. I'd go for at least the 12 or even back to the stock 14.

Another thing to check if you reload your own ammo is that you might not be seating the primers the whole way as consistently as you should be doing. A primer that isn't quite seated will soak up a lot of the firing pin energy in bedding down that last few thou. Or the dimple will push the anvil in the cup against the base of the pocket where it should have been in the first place. Either sets the primer up to ignite properly with the NEXT hammer strike. So use a little more pressure for seating the primers with the next batch of ammo.

 

[98Redline]

For any gun other than a range toy, I would leave the stock hammer spring in place. I want to be positive of the gun going bang when the trigger is pulled.

To help offset this, a good trigger job, where the internal bearing surfaces of the trigger mechanism are polished to mirror smoothness will help tremendously.
Also the addition of a set of hammer shims can help prevent energy from being robbed when the hammer drags against the frame.

The Ruger SP, GP and SRH action can be tuned to have a very nice pull and break while still retaining the factory spring to ensure consistent ignition.

 

[g.willikers]

Nobody wants to hear that the problem might be them, but...
How the gun is gripped has a lot to do with the effort it takes to pull the trigger.
A good and proper grip, especially for a double action trigger, can make all the difference.
The trouble is that it's nearly impossible to explain from long distance.
Thankfully, Jerry Miculek has some excellent videos on youtube and his own web site.
They greatly help, especially with revolvers.
No surprise there, of course.

 

[Jim K]

Believe it or not, gun makers don't put in springs of a certain strength just so folks who think they are smarter can take them out and go for weaker ones.

The gun maker will use a mainspring (hammer or firing pin spring) that has sufficient power not only to fire harder primers but to make up for adverse conditions, like cold, dirt, gunk, hard grease, and so on. When the owner chooses to remove some of that extra edge and lighten the spring(s), he increases by some degree the chances of a misfire. Whether that is acceptable is the owner's choice, but he needs to understand that making the gun easier to operate may make it less reliable.

Jim

 

[Glock Doctor]

^^^ this!

 

[Drail]

Lighter springs can make a revolver less reliable with the harder brands of primers but with fully seated Federal primers it's actually pretty ridiculous how light you can go and still get reliable ignition. But then you're stuck with Federal primers only. Those are the only brand I buy anyway. If you can remove all of the frictional drag on parts and the frame they ride in you can get by with stock or slightly lighter than stock springs. But on a serious carry gun I use the stock springs just because I want 100% ignition and I want the trigger to reset as quickly as possible. People who see Jerry Miculek for the first time almost always claim that his gun has had trigger work and lightened springs. Nope. With lighter springs he can actually outrun the trigger reset and have to wait for it to catch up with his finger. He uses full power springs in his revolvers. He also has full power hand strength.

 

[Old Fuff]

Believe it or not, gun makers don't put in springs of a certain strength just so folks who think they are smarter can take them out and go for weaker ones.

The gun maker will use a mainspring (hammer or firing pin spring) that has sufficient power not only to fire harder primers but to make up for adverse conditions, like cold, dirt, gunk, hard grease, and so on. When the owner chooses to remove some of that extra edge and lighten the spring(s), he increases by some degree the chances of a misfire. Whether that is acceptable is the owner's choice, but he needs to understand that making the gun easier to operate may make it less reliable.

Absolutely true! And I couldn't have said it better myself. Revolver manufacturers presume that they're is a good possibility that if someone resorts to shooting in the double-action mode it's because of an emergency. Consequently spring selection takes this into consideration.

 

[The Lone Haranguer]

The reason it fires in single action, but not double, is that single action draws the hammer back farther and holds it there until you pull the trigger. There is more stored energy to strike the primer with.

I have always felt that trigger actions are improved more by polishing and fitting of parts and leaving the springs alone.

 

[Vern Humphrey]

The gun, like almost all double action revolvers, has two sear release positions. When firing double action, the hammer doesn't come back as far -- cock the gun, mark the frame with a grease pencil even with the front of the hammer, then uncock and slooooly pull it through in double action -- you'll see what I mean.

What this means, it the hammer has more time to build up speed in single action.

The lesson here is, when changing springs in a double action revolver, test it in double action FIRST.

 

[Bullseye]

Thanks everyone .... I bought the Wolff springs pretty cheap and thought it would do just the opposite and make my DA pull lighter and also help me to keep such a short barrel on target therefore helping it be a better defensive firearm. I rarely fire any revolver in DA if I have a choice. But thinking of being in a pinch I wanted the smooth light pull.
I got it, but I will be either putting the original back in or just dropping down from 14 lb to the 12 and trying to repeat a misfire. Never thought about the travel issue. Makes sense to me. Ya learn something new everyday!

 

[Old Fuff]

Don't be in a hurry if you have a "failure to fire." A quick pull of the trigger will rotate up and fire the second chamber about the time the first one, that was only delayed, also goes off!

At this point the top strap and upper half of the cylinder may go into orbit.

 

[5-SHOTS]

When I owned a Ruger SP101 DAO I purchased two spring sets, one from Wilson Combat and one from Wolff. After some experiments I went back to the original 14lbs Ruger spring: my SP101 was not 100% reliable with aftermarket springs when staging the trigger for long distance shots.

 

[Waveski]

Fuff :

"Don't be in a hurry if you have a "failure to fire." A quick pull of the trigger will rotate up and fire the second chamber about the time the first one, that was only delayed, also goes off!

At this point the top strap and upper half of the cylinder may go into orbit. "

Man , that's good advice!

 

[Bullseye]

My 14 lb spring is back in place.

 

[Old Fuff]

"Don't be in a hurry if you have a "failure to fire." A quick pull of the trigger will rotate up and fire the second chamber about the time the first one, that was only delayed, also goes off!

Another unhappy consequence of a light hammer hit is that the first shot is a squib, caused by partial ignition.

With a bullet stuck in the bore, you put a fast, second one on top of it.

 

[Drail]

Extremely good points here - pay careful attention - if anything doesn't feel or sound right - stop - wait a few minutes and check that bore. Always assume the worst case scenario.

 

[Vern Humphrey]

One trick I've tried is to get the most abrasive tooth powder you can find, mix it with a drop or two of oil and smear it sparingly on the SIDES (the non-working surfaces) of the hammer and trigger and similar parts. Then you spend an evening or two dry firing, then disassemble, clean thoroughly and re-lube.

What this does is polish both the sides and the frame where the sides slide back and forth. This will usually produce a noticeably smoother DA pull.

 

[buntline]

For what it's worth, I just inherited a bunch of revolvers that had been well kept in terms of keeping them clean and dry but had not been lubed for quite some time in this hot, dry climate.

Nearly 1/3 of them would not set off a primer when fired DA right out of the cases they were kept in, but they all quickly recovered after being drowned in WD_40 and never missed a lick. Of course, that is not a proper lube for long term, but it illustrates what a build-up of friction can do.....Joe

 

[Confederate]

Sometimes a gritty action can create problems in double action with a lighter spring. But I'd call the manufacturers of the spring and have them send me a little heavier one. Then I'd dry snap the living daylights out of it. I had this problem with a Security-Six. The spring was just a little too light. I dry fired it hundreds of times, but still got the occasional misfire in double action. When I got an extra pound on the spring, the misfires stopped and I had a super smooth action. Ruger's double-action springs are too bloody stiff for my taste and always have been. But its handguns are incredibly good.

 

[Vern Humphrey]

For what it's worth, I just inherited a bunch of revolvers that had been well kept in terms of keeping them clean and dry but had not been lubed for quite some time in this hot, dry climate.

Nearly 1/3 of them would not set off a primer when fired DA right out of the cases they were kept in, but they all quickly recovered after being drowned in WD_40 and never missed a lick. Of course, that is not a proper lube for long term, but it illustrates what a build-up of friction can do.....Joe

Brake cleaner, followed by thoroughly lubing the gun will do wonders.

 

[Rock185]

My SP-101 performed flawlessly with any and all ammo I tried. But, since I know a lot more than the engineers who developed the spring specifications for the SP-101, I changed my SP-101 mainspring from the factory 14# to a 12#. I immediately started getting misfires with harder primers due to light primer strikes. I changed back to the factory mainspring. Never another misfire....ymmv