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Old 11-17-2011, 08:02 PM
scooter123 scooter123 is offline
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First, when I tune my triggers my personal goal is 100% reliable ignition with ANY ammo that is commonly available and I'll try multiple brands to insure I achieve this goal. Ammo's that I've used in my testing are Speer Lawman TMJ, American Eagle & Federal Champoin, Remington UMC, and Winchester White Box. I'd like to try some Sellier & Belloit due to recent complaints about "hard" primers in this brand but it seems to have dried up in my area. I've also conducted tests for accuracy because I discovered early on that there is a region between 100% ignition and good accuracy where partial ignition of the primer can occur. The effect of this is vertical stringing when shooting from a rest. If you see degraded accuracy when pushing the limit for "light" adding 1/2 to 1 lbs. to the trigger should bring the accuracy back up to snuff. Keep this in mind when you read the following, I'm a bit more conservative than some when tuning for a light DA trigger. Because I've actually tested for the effect on both ignition and accuracy.

To some extent it's dependent on whether the revolver has the firing pin in the frame or on the hammer. With the frame mounted firing pin there are several aftermarket firing pins available. So, you can install a longer firing pin that also offers an extended travel provision compared to the factory firing pin. Personally I've been using the Cylinder & Slide firing pin and have had perfect reliability with a DA trigger set ot 8 lbs. I could probably take it lighter but I've found that 8 lbs. works quite well for me.

With a hammer mounted firing pin I'm more conservative and tune them to 9 lbs. I'm sure that lighter is possible but with the hammer mounted firing pin you can't swap in a longer firing pin if you find your accuracy has fallen off. While a bit heavier, in a well tuned action the difference between 8 and 9 lbs. really isn't noticeable unless you shoot the 2 guns side by side.

I'll also note that you should do your best to make sure that the rebound and mainspring are "in balance". While it's not too critical, trying to tune to an 8 lbs. DA trigger with the factory rebound spring will require reducing the mainspring power to the point where misfires may be an issue. Generally when I tune my guns I start by installing a 14 lbs. rebound spring, lighten the mainspring tension, and then measure the results. If a previous owner hasn't "adjusted" the SA sear on the trigger, this combination will result in an 8 lbs. DA trigger and a 3 lbs. SA trigger in a well balanced action.

However, with guns that have had some previous tinkering with the sear on the trigger, this combination can result in a single action trigger that breaks near 2 lbs., much lighter than I am comfortable with in a handgun. In this case IMO the best way to correct this is to stone the sear on the trigger back to the original factory profile, however with an older Forged trigger that stoning may remove any remaining case hardening and you may have to replace the trigger. This is one reason why I am NOT a proponent of tweaking the single action sear on the trigger to adjust the SA break, today it's much easier to select the proper weight of rebound spring to achieve the same goal.

Finally, if you want to start tuning your triggers I can tell you it's not very difficult. You will need to pay attentions to the details and should have a detail oriented mindset, but it's NOT some black art that takes years to learn. I would recomend that you start by purchasing the Kuhnhausen S&W Shop Manual and Jerry Miculeks Trigger Job DVD before you start. The manual covers the basic features of a good action tuning and Jerry's DVD covers achieving good balance and fills in some of the gaps due to design changes in the more recent revolvers. You'll also need some tools, a good trigger gage that repeats consistently, a 6 inch arkansas stone, a selection of rebound springs, and I would suggest at least 2 strain screws correct for your grip frame.
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