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Posted: 1/5/2009 11:33:56 AM EDT
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Hey Gang
I just seated primers for the first time. I am using the Lee aniversary press with the manual press mounted primer (not the handheld one). I am using CCI small rifle primers and RP once fired brass (primer pockets have been cleaned) When I seat the primers, I am applying a moderate amount of force, and they seem to seat without a problem, but I read somewhere that you shouldnt seat them too deep (crush them) when i try to check the depth with my calipers it looks like they are seated about .008 to .010 below the case rim. Is this ok, or am i seating them too deep? is there a possible safety issue if they are seated too deep? I did chamber a few of them, and they did fire in my rifle......but I just wanna make sure I am doing this correctly before I do a whole bunch of them. Thanks fer the help P.Smith |
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I've seated about a billion primers (at least it seems like that many). I've never crushed one or seated it too deep. The only damaged primers I've had were smashed from either trying to seat them sideways (by accident obviously) or a primer pocket crimp that got missed.
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When I started reloading I seated primers hard enough to get a little crush; that's not necessary and probably cracks the priming compound. I use a hand priming tool, so there is adequate "feel" to determine when I hit bottom.
0.008 inches deep is about maximum for AR rifles. If yours ignite reliably, don't worry about this batch, but try to back off on the next one. Seat primers subflush about 0.002 to 0.008 inches. Once you feel firm resistance on the press handle stop. Or switch to hand priming if you can't determine when the primer is seated on your press. |
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Seat the primers until you feel them bottom out, then stop all force. Done.
It does take some experience to "feel" the primer bottom out. Load up a small amount of what you have primed. Shoot them, then you will know from your own experience if they are seated correctly. Too much force will flatten the top of the primer. |
| The books I have read on this subject recommend .005 below. The above post is correct you want them bottomed out but not flattened. Different brands of primers are slightly different heights so measuring the depth will vary. Just be sure not to have any of them high with a floating firing pin ( such as an AR15). |
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From the Speer manual..........
Repriming is a simple, but critical, step that reloaders often do not give enough attention to. In order to gain optimum primer sensitivity, it must be seated firmly to the bottom of the primer pocket. But this doesn't mean using so much force that the primer cup is deformed. When primers are properly seated, the top of the primer is from .005" to .008" below flush with the case head. The purpose of this is to assure that the primer anvil legs are in firm contact with the bottom of the primer pocket. If they are not so seated, it requires an average of 59% greater firing pin blow to give reliable ignition. This much extra force simply isn't available in many firearms. Analysis of hundreds of handload misfires complaints show that the vast majority are caused by insufficient primer seating. You can check............by running your finger along the bottoms of your cases. You'll learn to "feel the primers" as they should be seated below flush. If, after completing the reloading operation, you discover some rounds with high primers, do not attempt to reseat the primer in a loaded round. To do so is extremely hazardous! The chance of a primer firing during proper seating is extremely remote. Yet, if it does, it will ignite the powder in the case and you have a home-made "grenade" right before you. If high primers are discovered, remove both bullet and powder charge from the case before attempting to reseat the primer! There is no safe alternative. HTH. Aloha, Mark |
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