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Joined: 14 Nov 2011 Posts: 164 Location: Minnesota

I reload with a MEC sizemaster and I was having some issues at the range with light primer strikes. The light strikes were inconsistent and in both barrels. I am wondering if I am pressing the primers too deep. Any easy ways to check correct primer depth? Should you feel the edges of the primer cup running your thumb across or perfectly smooth? Reloading cheddite hulls with ched or noblesport primers. I am going to try some factory loads tonight and see what the primer strikes look like. I am trying to determine if this is a ammo or a gun issue. Firing pin protrusion was checked by a gunsmith and said it looked fine but I did not get the measurement from him.

*Last edited by skeettx on Thu Jun 26, 2014 8:48 am; edited 3 times in total*

Just below flush
The MEC Sizemaster should NOT be causing a primer seating concerns
as it uses a post system.

http://www.hodgdonreloading.com/reloading-education/reloading-beginners/primer-seating-depth

http://www.shotgunworld.com/bbs/viewtopic.php?t=225203

Hopefully NOT your new beautiful gun?????

Mike

Joined: 14 Nov 2011 Posts: 164 Location: Minnesota

MEC Sizemaster. Thanks for the links. I will check the head space also and see what that looks like and load a few out of new cheddite hulls. These were with herters (cheddite) hulls that have been reloaded 3 or 4 times

On a few guns with the rim cut made too deep, I have insured ignition
but placing a SMALL bit of scotch tape on the forward side of the shotshell rim to hold the hull more rearward.

Hopefully your gun will not close easily if a SMALL bit of tape is applied to
the forward rim of a hull and then seated.

Mike

Joined: 26 Apr 2010 Posts: 3177 Location: NCWa

One thing that I have found in my reloads that contributed to some mis-fires was pressing the primer in so firmly that the base of the shell warped inward. The result was a shotshell that had a concave head. This slight dishing caused no difference when frired in several guns, but when fired in a well used Rem 870, about 1 in twenty would fail to fire. When examined, the primer had a slight dent, so the combination of the worn firing pin spring and it's light strike, mixed with a primer that was further in the chamber, due to the dishing of the head resulted in the mis-fires. The mis-fired shell were fired in one of the other guns and they fired normally.

Shotshell primers should be seated just deep enough so the flange or edge of the primer cup does not contact the breech or bolt face. A scant few thousanths of an inch just below the shell face is deep enough.

Adjusting the primer seating ram pressure should allow you to adjust the primer seating depth. Using a flat straight edge laid edgewise across the base of a primed hull is the easiest way to check. You should be able to see a very tiny amount of light between the primer cup edge and the straight edge when held up to a light source. Any more than that might be too deap.

Be advised. Different brands and even different lots of a given brand of 209 size primers from different years of production can and do vary slightly in diameter. Best mike the diameter of some of your spent primers, and those of your new ones. New primers should very closely match the diameter of the spent ones. Those with smaller diameters can and will probably seat too deeply.

Enlarged primer pockets in your used hulls can and will also cause the same problem. Going to a slightly larger diameter primer may solve that problem for a few more loadings if the hull mouths aren't already worn out. After that, it should be time to toss out the old used hulls anyway. Hope the info helps.