Primer Seating Data for Extreme Long Range

[Chad Schmidt]

Thanks to everyone for investing your experience in my query.
Chad

 

[Canadian Bushman]

Just for those interested, the K&M primer seating depth gauge takes all the measurements that Alex mentioned into account for each case individually.

Its not exactly fast, but for what it does, it is a pretty neat tool.

 

[TK50]

By using a primer pocket uniformer on all cases and a Sinclair type primer seating tool you can achieve the results you are looking for. The Sinclair hand seating tool locks the case head up against the seating tool so that any variation in case rim thickness is not a problem. As Alex stated that is the result you are striving for.

 

[Alex Wheeler]

I think we should understand what we want to achieve. There are a couple aspects to primer seating. One is the distance the firing pin travels to strike the primer. There are vibrations involved with ignition and we want to keep them consistent shot to shot. So consistent shoulder bump, primer pocket depth and seated primer height are important for consistent firing pin travel. Its not just about primer height because they may vary in height and a crush fit is also important to having consistent ignition of the primer. A hard seated primer and a light seated primer will not shoot the same. So this comes back to seating by feel. The K&M is an option, I have one but prefer the better feel I get from the 21st century. After they are seated you can now sort them by primer depth which will be the variations in the primer itself. The depths will be very close. The 2k match is just getting started and competitors will be doing alot of testing over the years to see what matters at this range now that there is a group match that demands that precision.

 

[Canadian Bushman]

I think we should understand what we want to achieve. There are a couple aspects to primer seating. One is the distance the firing pin travels to strike the primer. There are vibrations involved with ignition and we want to keep them consistent shot to shot. So consistent shoulder bump, primer pocket depth and seated primer height are important for consistent firing pin travel. Its not just about primer height because they may vary in height and a crush fit is also important to having consistent ignition of the primer. A hard seated primer and a light seated primer will not shoot the same. So this comes back to seating by feel. The K&M is an option, I have one but prefer the better feel I get from the 21st century. After they are seated you can now sort them by primer depth which will be the variations in the primer itself. The depths will be very close. The 2k match is just getting started and competitors will be doing alot of testing over the years to see what matters at this range now that there is a group match that demands that precision.

When you sort primed cases for primer depth, you use the shoulder as a datum?

 

[Alex Wheeler]

You use a depth mic from the case head. You would also sort out cases that bumped differently.

 

[Canadian Bushman]

You use a depth mic from the case head. You would also sort out cases that bumped differently.

This is outside my experience. Ive never gone that deep.