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DPSTex
HB Full Member
| Joined: | 15 July 2008 |
| Location: | Leander, Texas USA |
| Posts: | 13 |
| Photo: | | | Are you a handloader?: | Yes | | Favorite type of cartridge to load?: | rifle |
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Posted: 18 July 2008 07:11 PM |
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Hey dudes.....
My question is this....which has will have more effect on reliable ignition of the primer, firing pin speed, or firing pin mass. Example, my little Win 52 sporter, sometimes will snap and not fire a cartridge (about 1 out of 20), the firing pin has been significantly modified already, (went from cock on closing to cock on opening,shortened the firing pin fall 50%[it used to have 3/4" travel, now has 3/8" travel, not yet as short as my 52C match rifle which has about 3/16" travel]) when I finished the changes on the firing pin, I added back the weight that had been removed in the process, to maintain the mass. Assuming the same spring, will a faster lighter firing pin be more reliable, or will a slower but heavier firing pin be more reliable. I am aware that force = mass x acceleration, but who's got numbers for all of that?!?!?!
Thanks,
Darryl
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DPS
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ghrit
HB Life Member
| Joined: | 14 April 2006 |
| Location: | Endless Mountains, Pennsylvania USA |
| Posts: | 223 |
| Photo: | | | Are you a handloader?: | No | | Favorite type of cartridge to load?: | none |
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Posted: 19 July 2008 04:26 AM |
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I'll take a shot at this. What fires the primer is not force, nor mass, but energy. Energy is a function of mass and velocity not acceleration. (My physics book is packed for the move so I can't check it, but I think I remember that E-1/2mv^2. Since we don't know the spring rate nor the weight of the pin, it doesn't matter for now.)
Thus, faster and lighter might just come out to the same energy as slower and heavier. From what you say, I'm jumping to the conclusion that the modifications include both lightening (shortening?) the spring AND the pin, then adding weight to the pin. That reduces the energy that would be applied to the primer. So I'm highly suspicious that you've got the whole thing too soft to be reliable. Now, that said, I don't know enough about the actual bolt to make a flat statement that is the cause. But I'd say the least cost to gain some reliability (from where you are now) would be a heavier spring.
The heavier spring will do two things for you. First, you'll get more energy in the pin as it falls (moving faster) and second, your lock time will be quicker for the same reason. You might also take the extra added weight off the pin and going to an even heavier spring for faster lock time without reducing the energy.
Taking a direct shot at the question "Assuming the same spring, will a faster lighter firing pin be more reliable, or will a slower but heavier firing pin be more reliable." That has no straight answer, since speed and mass are both part of the equation, and the balance between them must meet a minimum energy. The answer probably is faster and/or heavier for reliability; either one will increase energy at the primer.
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