"Hair Trigger" on my 64-8

[Hurryin' Hoosier]

My 64-8 is a pleasure to shoot double-action, but in single action it is almost a hair trigger. Any way to lengthen the pull or increase resistance withour affecting its double-action performance?

 

[kbm6893]

I've yet to see a S&W that wasn't a hair trigger in SA mode. That's the pleasure in them, and also the reason why it is a BAD idea to cock a hammer in a self defense encounter or while investigating a bump in the night. People see actors do it on TV and think it looks cool. For target shooting, a hair trigger is the way to go. I love the sensitivity of the trigger in SA mode.

 

[jj2am44]

Make sure you don't have push off. Unload the gun and cock the hammer. See if you can push the hammer forward. If you can, you have push off and must be addressed by a qualified smith or S & W themselves.

 

[jimmyj]

Anything below 2.5# is too light.
If your revolver is "Pre-Owned" possible a "Kitchen Table" action job took too much metal off the sear.
I would have a Gunsmith check it.

 

[chief38]

Assuming that you do NOT have a "push-off" problem, you can make the pull slightly heavier by increasing spring weight, or using a longer strain screw - will also make DA pull heavier as well. A light (obviously I do not know exactly what you deem "too light") SA trigger pull with NO push-off is not a problem to me, because the SA mode of firing the revolver is not usually a self defense method of firing. It is reserved for an aimed shot usually at a distance. I have S&W revolvers that have a SA trigger pull of around 2 to 2 1/2 pounds and they are fantastic. They do not have any "push - off" and I do NOT cock the hammer unless I am deliberately ready to fire the gun.

Do you have access to a trigger pull scale? You should actually weigh the trigger pull to see exactly what is.

Chief38

 

[Sarge1644]

The above advice is sound. Have a Smith & Wesson Armorer check for "push off", which is an unsafe condition. In most cases, it is an easy fix.

 

[TheTinMan]

I've yet to see a S&W that wasn't a hair trigger in SA mode.

Some have light, clean trigger pulls. Most don't right out of the box in my limited experience.

Is it possible that someone put a reduced power rebound spring in there? If so, a full power rebound spring might help and would be a relatively easy thing to try. It would increase your DA trigger pull slightly.

 

[scooter123]

First, a note on Pushoff. Many people will recomend to check for pushoff without mentioning the potential that exists for creating this problem simply by testing for it. IF YOU PUSH TOO HARD YOU CAN CREATE PUSHOFF IN A REVOLVER THAT PREVIOUSLY WAS WORKING PERFECTLY. Limit any force applied to just the weight of the gun. Basically, balance it on your thumb with the barrel pointing straight up and see if the hammer releases. Yeah, a VERY conservative test but it's better to be conservative instead of causing enough damage that the only repair option is to replace both the hammer and trigger. Most gunshops won't object to a balance test for pushoff, however if they see you trying to push the hammer off with force they may take it from your hands and beat you senseless with it.

Historically, the SA trigger pull on a S&W revolver was lightened by stoning the SA sear on the trigger to what I call an "assist" angle. Basically, the sear is "sloped" slightly in a way that the sear on the hammer is "sliding downhill". This is a practice the is NOT necessary today and a practice that I do NOT endorse. Because it puts ALL the wear on the tip of the sear on the hammer and WILL lead to pushoff as the sear on the hammer wears.

Today the best way to adjust the SA trigger weight is by changing the rebound spring. I've found that a 14 lbs. rebound spring will result in a 3 lbs. SA trigger pull in most cases, provided the DA trigger pull has been tuned to the 8-9 lbs range. Because there is some interplay between the mainspring tension and the SA trigger weight you do have to do a bit of back and forth when selecting the correct rebound spring. However, even with the mainspring producing a 12 lbs. DA trigger pull a 14 lbs. rebound spring will result in an SA trigger pull in the 3 1/4 to 3 1/2 lbs. range. So, mainspring power only has a minor effect on the SA trigger weight. What has the greatest effect is the rebound spring and whether the SA sear on the trigger has been reground to an assist angle.

Obviously, a good trigger pull gage is a very useful item to own when working on these triggers. The one I like is the Lyman Digital, at about 70 dollars it's not hugely expensive and I've found it easy to get repeatable results with. However, it's maximum limit for weight is only 12 lbs. and some new S&W revolvers are shipping with DA triggers over 12 lbs., so caution must be used if checking the DA trigger on a brand new S&W.

An alternative to using a trigger gage is a simple string with a known weight attached to it. To make up those weight you can use a basic and cheap Postal scale, just start stringing large nuts or anything handy and weigh it. Take a bit of hanger wire, bend it to a hook to engage the trigger and make a loop for the string that is located behind the frame. BTW, add that bit of wire to your weights so you include it's weight in the total.

Now that you are set up to determine the true break of your trigger it's time to see where it is. Personally, I strongly prefer a 3 lbs. SA trigger, which some may consider a bit light. Out of the box a factory new S&W revolver today will have a SA trigger in the 4 1/4 to 4 1/2 lbs. range. Take that factory new revolver and install a much lighter 12 lbs. rebound spring in it without doing anything else and you should see a SA trigger in the 2 1/2 lbs. range. Tune the DA trigger to 8 lbs. and it will only drop to 2 1/4 lbs. If you see a SA trigger BELOW 2 1/4 lbs. it's near certain the SA sear on the trigger has been stoned to an assist angle no matter what rebound spring is installed.

This means you will need to re-sharpen the SA sear on the trigger before doing anything else. I'll also note that any gun that was used a lot in single action with an assist angle on the trigger sear WILL need to have the hammer replaced because it's been "worn in" to match than assist angle on the trigger sear. Since the total length of the sear on the hammer is only about 0.005 inch, reshaping that surface is not an option. Now you know why I will NEVER endorse re-shaping the sear on the trigger to an assist angle, hammers aren't cheap and can be difficult to find.

If you find you need to "sharpen" the sear on the trigger there are two things to keep in mind. One is that trigger is likely to be case hardened and that hard casing is likely to be about 0.015 inch deep, a common casing thickness for case hardening steels. So, take a LESS IS BEST approach to try and avoid stoning thru the case hardening. That means STOPPING AS SOON as you see that fresh surface evenly meet the tip of the sear and going no further. Second, see the link below for what I consider the ideal jug for stoning this sear. Note, you'll also want to do your stoning using only about 1/4 inch on the tip of a 6 inch long stone, meaning short back and forth strokes.

http://smith-wessonforum.com/s-w-smithing/195061-tuning-jigs.html

PS; kudo's to Gizamo for posting a superb idea and illustration for a trigger tuning jig.

PSS; By formal definition a "hair trigger" is a trigger with very little Sear Creep and weight is NOT a factor in this. Basically, you can have a 50 lbs. trigger pull in a "hair trigger", what makes it a "hair" is that the total amount of movement is about the thickness of a human hair. Normally in the larger S&W frame sizes the total amount of Sear Creep on the trigger is between 0.015 and 0.018 inch, so they are all quite close to being "hair triggers".

 

[Hurryin' Hoosier]

My 64-8 is a brand-new gun which has never had any "shade tree mechanic" work done to it. Maybe it's just a matter of me needing to get used to it. I doubt that I'll ever have any occasion to shoot it SA, anyway, and it's great in DA.

Thanks for all the responses.