Another Primer Question

lew07

Please can any one tell Me. How does a manufacturer determine the size of a primer needed in a cartridge? Is it length of cartridge (ie depth of the powder) width of base of cartridge? Size of bullet? Any thoughts appreciated [:)]

iceracerx

One might suggest that pressure generated by the burning powder would be the determining factor in choosing a primer.

XXCross

I would suggest that since we are talking about the ignition of progressive burning propellants, it is only necessary to have sufficient force (heat and duration) to insure that the charge is reliably "ignited". Even if only a small percentage of the charge is heated to ignition temperature...the powder will do the rest.

perry shooter

I have reason to believe the amount of powder has something to do with
what size primer is used in factory loaded ammo also the diameter of the inside of the case This along with peak pressure I have found that at least in bolt action rifles chambered in 22 HORNET small Pistol primers shoot smaller groups than small Rifle primers I think it is because the primer cup is thicker /harder on rifle primers than pistol primers and the bolt on 22 Hornet rifles has smaller weaker Firing pin spring.than bigger bore rifles with larger receivers YMMV

62fuelie

I agree with P/S the type and density of the powder load also have to be taken into consideration. Ball powders tend to be a bit more difficult to ignite and very large powder loads i.e. magnums would benefit from more of the charge being exposed to the primer flame so that the burn surface area is larger and the charge is fully consumed before the projectile leaves the barrel.

mrmike08075

I have found that the most consistent velocities and group sizes come from front ignition - tubed primer loads that compress the powder and seem to provider a better - repeatable - performance enhancing load.

I know that most will never attempt this method and it's somewhat of an advanced skillet that has the potential for problems.

I played with the concept with my .270 Gibbs based on suggested load data and techniques layed out by Rocky Gibbs

Mike

tsr1965

With the consistency that is happening in today's ammunition and component's, I see no advantage to tubed frontal ignition systems.

There are many variables that come into play when determining what size the primer should be in a case. Diameter is one...for large and small primers.

Case capacity is another variable. The higher the capacity, the hotter the flame needed/magnum primer.

Power burn rate is yet another...the slower the burn the hotter the ignition.

charliemeyer007

I wanted to build a tubed ignition 45-50BMG. Charles O'Neil, Elmer Keith and Don Hopkins did work on the concept of caring the flash forward to the base of the bullet before WWII. Better throat life was one of the claims along with higher velocity.

In the early days 357's were large pistol. Now they make 45 ACP with small pistol and 308 with small rifle.

A 50 BMG primer is about the same as a 38 S&W load.