Changing primers during load development?

[Boss Hoss]

Edited

 

[Edd]

I always get a laugh at the poor folks who think they can judge high pressure by looking at the primer! If you do this you may be in for a very rude awakening someday LOL. Depends on who built your rifle and what components in the firing system they used.

How does firing system components effect the flattening of primers?

 

[Bart B]

How does firing system components effect the flattening of primers?

Firing pin tip diameters as well as firing pin spring strength will effect how the priming mixture detonates. Weak springs and smaller tip diameters cause milder detonations. Strong springs and large tip diameters transfer more force to the primer mix creating more detonation power/flame.

 

[Edd]

Firing pin tip diameters as well as firing pin spring strength will effect how the priming mixture detonates. Weak springs and smaller tip diameters cause milder detonations. Strong springs and large tip diameters transfer more force to the primer mix creating more detonation power/flame.

Do you have any pressure data on this?

 

[Bart B]

Do you have any pressure data on this?

None except that replacing a weak firing pin spring with a new/strong one makes bullets shoot out faster. And with more uniform velocity. Top long range competitors have known this for decades.

Made some tests years ago with a Win. 70 spring that had dropped to 20 pounds of force from the factory standard of 23 pounds; 'twas cut off to drop the force to about 16 or so pounds which was just enough to consistantly fire the primer. Bullets dropped about 2 or 3 more MOA at 1000 yards and vertical stringing went from about 4 inches with a 26 pound spring to about 25 inches with the weak one. This was years ago and I'm remembering as best I can, but weak springs do cause lower bullet velocity and higher velocity spreads. But if muzzle velocity drops and spreads for the same load on the same day with the same ammo as it shot great with a heavier spring, that's proof to me the peak pressure followed the velocity direction and spread.

 

[Edd]

I'm still trying to understand why any of this stuff you are describing would have no effect on primer flattening. It seems to me a primer would react anything you did to the firing components that increased or decreased the pressure.

It was implied that certain components in the firing system would allow the pressure to be at dangerous levels without that pressure showing up on the primer. Or maybe that was't what was implied. Maybe he was saying that some components could be spit back into your eye before the primer flattened.

 

[Bart B]

It was implied that certain components in the firing system would allow the pressure to be at dangerous levels without that pressure showing up on the primer.

If the primer's got an extra hard/thick cup, that'll not show higher pressures and/or primer dimple cratering from more pointed firing pin tips.

 

[Bart B]

I always get a laugh at the poor folks who think they can judge high pressure by looking at the primer!

Their peers oft times think if the primer pocket opens up enough in 2 reloads such that it won't hold a new primer, the load's still a safe one to shoot.

Their dumber peers don't think pressure's too high even if the primer falls out of the case upon its ejection but they can find the primer. Maybe if they can't find the primer, then the load may be a bit too hot.