I decided to replace my main spring on my 40 year old Mod 14 because the strain screw was turned in so far that it was bottomed out. I didn't have any misfires but figured that after thousands of rounds and being 40 years old that it was time to replace before I started having problems. I also felt that the hammer fall was slower that normal this last year and my scores were dropping in BE and DR. I received a new S&W main spring from Brownells and preceeded to put it in. Now in the single action mode it's alot harder to pull the hammer back and double action trigger pull is about twice of what it was before the spring replacment. My questions are, will this new spring weaken in time ( meaning should I dry fire it a couple hundred times)? Did S&W change the weight on these new springs? And is there a prefered method of adjusting the strain screw besides turning it all the way in?

The 14 is used for Bullseye shooting and Distinguished Revolver so a misfire while upsetting would not be life threatening. The main reson for the main spring change was the deteriorating accuracy of this gun and I was attributing it to a slower than normal hammer fall and me pulling the gun off target while the hammer was falling. In a Ransom Rest the 14 still shoots fine with the old main spring and this last Bullseye season I shot my old Mod 28 much better so I don't think it's my shooting skills getting worse.

Kirmdog

Actually, the S&W leaf mainspring design is extremely durable, and weakened springs are rare, while broken springs are extremely rare. Amatuerish attempts to reduce mainspring strength (filing or grinding spring thinner) is what usually causes spring failures.

Cycling is what weakens coil type springs. Leaving under full compression is what weakens leaf springs. While replacing your mainspring is a noble idea, 40 years is nothing in terms of spring life. The fact that your revolver shoots accurately in a Ransom rest should be evidence enough that it shoots competitively. Locktime in a revolver is but a minor factor in how well YOU can shoot.

Revolver smiths recommend adjusting the tension screw outwards until misfires start to occur with the hardest primers (CCI or Winchester brand) and then turning the screw in one full turn and using Locktite thread sealant to secure it.

SW strain screws are designed to be cranked all the way down until they bottom out.

It will weaken very little if at all. If you want to weaken it. you have to bend it.

Some of us set the springs up so the "operating" point is with the strain screw maybe 1/4 turn out, and the screw MUST be set in with blue Loctite if you do. This lets you run a light trigger with a little reserve spring if you run into some hard primers while you are shooting.... you can crank the screw down that last 1/4 turn.

The S&W factory doesn't use ANY loctite products, nor do I.
The proper method is to adjust the main spring tension by filing down the end of the strain screw, then re tighten it fully down.

Adjust the poundage to at least the minimum setting. Remember, the strain screw is always fully tightened, and the side plate is on when doing this work.

Gun empty, muzzle pointed upwards.
Dry fire gun and hold trigger fully to the rear.
Cock hammer with your thumb, then hook a 3 1/2 pound minimum weight around the end of the hammer.
The hammer must not move rearward when the gun is lifted.

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Thanks guys for the info.

Kirmdog