Reduce the strength of Pietta Spiller and Burr mainspring?

[Maillemaker]

Hi all,

The hammer pull (and trigger pull) on my Pietta Spiller and Burr is tremendous.

I am contemplating filing on the mainspring to weaken it. I've never done this before, but I understand that one should "swamp" the sides of the spring, not the main faces. In other words, we make the spring narrower, not thinning the thickness of the material.

Is this the right way to go about it?

https://i.imgur.com/x9HdZXxl.png

Steve

[Hal]

Steve,

That was my understanding as well, but I've never done it. Someone sent me these links. Pretty good article. It's about Pietta Colts, but certainly a lot of the info would apply to other Pietta models.

http://www.theopenrange.net/articles/Tuning_the_Pietta_Part_One.pdf
http://www.theopenrange.net/articles/Tuning_the_Pietta_Part_Two.pdf

[Muley Gil]

Yes, narrow the sides. I have done it to single action revolvers & to S&W revolvers. Make sure you polish the sides to a mirror finish. You do not want to create any stressors.

[Maillemaker]

No problem, I have a buffing wheel for polishing medieval armour.

Steve

[Maillemaker]

Any idea how much I should take off each side for starters? 1/16th?

Steve

[Eggman]

Being this is a revolver, I would take 1/4" off each side.
Muley talk about "stressors" please. I took down a jury rigged mainspring in one of my carbines a while back. Ground down the flat part of the flex part with a Dremel. I was careful not to generate any substantial heat, and was careful to keep the thickness even and not to create any noticeable dips in the surface. Took some time but finally arrived at a great trigger pull with a nice fast hammer fall. Been shooting the gun this way I guess five years.

[Maillemaker]

By stressors he means stress risers. Any sharp cut or notch will result in stress concentrations at that point and cracks will form and propagate from them. It’s why airplanes have oval windows instead of square.

[Muley Gil]

What Steve said! :D

[Chris Sweeney]

Umm - maybe the Spiller & Burr spring is gi-honkin'-normous compared to other repros, but since the widest of any of the springs in any of my Pietta revolvers is just about 7/16" I'm thinking that 1/4 inch off each side might be a tad aggressive, at least for the first pass. . .