c-g-designs

FIRING PIN SPRINGS

There is a discussion running on the subject running actually. Hereunder my 2 cents on the subject.  

The main effort  needed to lift the bolt is the necessity to compress the FP spring from fired to cocked position.

A spring is determined by the following datas :

1°) Outside diameter (OD).

2°) Wire diameter (W).

3°) Free lenght (L0).

4°) Lenght at maximal force (L1).

5°) Force at L1 (P1).

6°) Rate(P/f).

7°) Solid height (Sh)

P1 does not increase betweenL1 and Sh.

L1 is about the 2/3 of L0, depending on wire diameter.

P/f increase if W increase  and decrease if  OD increase.

A well calculated FP spring  should have both its cocked and decocked lenghts just under its L1 in order,not only ensure acceleration,but also to not add the rate P/f to the effort required during bolt lift. However, the working lenght shall not be close to Sh necessitating a quite long spring.

Things not to do :

            -Shorten the spring, as then one end i sno longer square and this makes the spring to  bent and  create frictions either (or both) on the firing pin or inside bolt diameter.

            -Use a spring of bigger wire diameter as then , L1 will be increased as well as the rate P/f . Also, the OD increase would create a risk of friction against the bolt ID.

In the case of the Remington, the solution would be to redesign the FP rod to reduce its outside diameter (same time reducing its weight) and adopt a spring of smaller diameter.

BUT ALSO, and certainly the best solution allowing the adoption of a lighter spring : reduce the FP tip diameter from 2mm (..080) to 1,6mm (.0665) this reducing by some 33% the necessary force needed for primer ccup indentation .  See previous article on this subject :

https://c-g-designs.blog4ever.com/en-on-the-subject-fp-diameters

R.G.C