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Analysis Of Trigger Pull Of A Lever Rifle

4698 Views 4 Replies 3 Participants Last post by  Trailblazer
I recently decided to look into reducing the trigger pull on one of my lever action Winchester rifles, since trigger pull was over 4 Lbs. (I would like it to be between 3 an 3-1/2 Lbs)

I got recommendations on how to go about adjusting the trigger pull and believe the recommendations were all appropriate. The recommendations included polishing and spring force adjusting (Cutting).

I decided that I should have an understanding of what influences how much trigger pull force is required to release the hammer on a typical lever rifle. There are several components that I identified that influence trigger pull. My interpretation is a simple analysis. I am sure that another analysis could be performed to provide a greater in-depth analysis than mine.

Here are my thoughts:
  • A] Hammer and Trigger engagement angle are critical (Lets assume that the engagements are optimized at a perfect 90 degrees).
  • B] Actual static friction between the hammer and trigger sear influenced by material, surface smoothness, and trigger-sear engagement pressure from the hammer spring.
C] Friction between trigger pivot bushing and trigger​
D] Trigger return spring back pressure​

Simplistically stated, total trigger pull force equals the total added forces of B+C+D.
All of these act in the same direction (opposite trigger pull) when attempting to pull the trigger.

Items B and C tend to be predominantly friction based, but item D is all spring pressure based.

Items B and C are the most difficult to correctly modify, therefore my efforts focussed on item D.

To determine how much of a contribution the trigger return spring was adding, I used a precision trigger weight set and measured the trigger return spring force. (Required me to hold the hammer back from engaging the sear).

Finding was that the trigger spring contributed aproximately 2 Lbs of force, therefore, reducing the force of the trigger spring to 1 Lb, should correspondingly reduce the overall trigger pull by 1 Lb.

In a week or so, I plan to check my calculations by installing a different trigger return spring.

Bob Nisbet
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