Rifle primer - seating depth Q.

[The Baron]

I have used a Sinclair primer pocket uniforming tool as part of my full case prep for many years. It's a one time operation and once the pockets are all uniformed they're good for the life of the case. I recently prepped a batch of 1F Win .22-250 cases and when I seated WLR primers they are all 0.010" - 0.012" below the face of the case head. I'll be shooting this ammo on the range so no big deal if I have misfires (unlikely anyway), but this is the first time I've had this result. I checked other ammo I had made and primers are just a few thou below flush. I checked to make sure the tool head had not started sliding out of the handle and it hadn't so I'm not even sure why this happened unless it is the primers themselves that are shorter (I used an old white card of primers I wanted to use up). Any one else ever run into this? Any problems with ignition?

 

[Longshot338]

I would take a new case, use your uniforming tool, seat a new primer (not the old white box stuff), and check the result. It should indicate if the primers are different. You could also try measuring the primers if you can find a consistent point to measure on. What it will not tell you is the dimensions of the anvil or the volume of priming compound within the cup.

I use a Hornady model pocket uniforming tool. Hasn't slipped; yet... I keep an eye on it. I deepen all my pockets to 0.006" sub-flush for my military firearms with floating firing pins (M14 and AR-15). I uniform my pockets for precision rifles to 0.003" below flush; more for the sake of consistency than anything else.

Hope this helps you figure out the problem.