Friday Aug 1st was firing pin frenzy day. I spent all day testing 3 different firing pin head designs and spring rates. Every part of this action besides the springs are made in house. Ordered a 4th axis VMC to help production of these small parts, their are over 1200 back in stock request for this action as of today according to our website analytics.
I was surprised my turn mill was able to make these as accurate as they are. With the new VMCs, ill be able to run multiple small parts and not tie up the big machines in anticipation to keep up with production. These are made from S7 round bar tool steel and heat treated.
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I tested 3 different firing pin designs:
Cresent/ half moon
Ball point pin (B14r style)
Traditional Wedge (V22 style)
All firing pins had the same protrusion and made within 0.0004" tolerance
Factory V22 firing pin on the left
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Our 22lr cases are work hardened near the outer rims, so precaution is needed to ensure the strike is just below the hardened brass and not to sharp to cause rupture, yet reliably ignite the primer without to much force disrupting/deforming the case rim.
Firing pin tuning from my testing is a significant way to tune your rifles accuracy and ammo. Just changing springs rates can tune a specific lot of ammo that didnt shoot well to being the best performer. This is often a neglected or overlooked maintenance item folks forget to change over time. Springs do fatigue over use and time. You can use a simple arbor press and small shipping scale to compress your springs and keep track of spring rates
The results of the Cresent/half moon produced the worst down range results and highest velocity SD spread. I gave this design a try after being told from a manufacturer who makes AR22 firing pins that this design helped increase reliability and better accuracy. I inadvertently had the opposite results with 5 shots from a box of 50 having a failure to fire
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I then next tried the Ball Point Pin (B14r style) and found decent results with average SDs of 7-12 but found random flyers with 3 out of the 10 five shot groups
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Final conclusion, the traditional wedge firing pin head produced the lowest SD spread at 4-7 and consistent accuracy. I did also see POI shift between all three types of firing pins and velocity swings 10-30 fps, confirming each pin did affect the ammos performance in some way. These small details I'm finding interesting in my personal chase of accuracy in 22lr. I would love to hear your guys thoughts / expirences
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