Thread: Primers not flush on brass - effect on measuring OAL and jump

The primers don't sit flush with the base of the brass when I seat them and they protrude a small amount. (Winchester 284 brass, federal 210 primers).

My question is in relation to how I will measure OAL to correctly know what jump I am seating my projectiles at. When chambered, I am guessing it will be the protruding primer in contact with the bolt face instead of the brass now? If so, when I measure OAL from the primer to the ogive of the projectile then I am getting the correct measurement for how much jump I am setting them at?

Hopefully that makes sense.

I’ve had the odd protruding primer with non cleaned primer pockets, eg 4 or 5 times fired without cleaning.

This is my favourite tool in my reloading arsenal.
Stainless Steel Priming Tool

Get them seated flush or you risk ignition on closing the bolt, much more serious than your OAL

Sinclair primer pocket uniformer. Cant have protuding primer. Serious problems.

Sound advice, will do.

Thanks

I don’t think you have any issues to worry about.

In 30 years of shooting I have never had, seen or heard of a proud primer being set of by closing the bolt. Happy to hear from any who have though?

As your cartridge head spaces off the shoulder or belt it will not impact the jump to the lands.

As long as your primer is seater in as far as it will go all is good. While flush is ideal a few slightly proud is no real issue in my option.

Problem solved. My Lyman priming tool wasn't pushing far enough on max extension. Made up a small shim to make it push further and boomfa they are going in flush now. Cheers all.

Flush is not correct. Seated so the anvil is in contact with the bottom of the primer pocket is. This may mean the primer face is a few thou in depending upon the brand of primer and the depth of the primer pocket. Teach the tip of your finger to measure this after each primer is seated.

Not having the anvil in contact with bottom of the pocket risks misfires.

I actually preload mine about 1 1/2 thou using a 21st Century tool. Difficult to do that using a press or most hand held tools.

Usually primers get seated too deep/are partially crushed by press priming.

Originally Posted by stagstalker

Problem solved. My Lyman priming tool wasn't pushing far enough on max extension. Made up a small shim to make it push further and boomfa they are going in flush now. Cheers all.

The Lyman hand tool is fussy about what shellholders you use, e.g. Lee shellholders are way too thick to work.

Originally Posted by Cigar

The Lyman hand tool is fussy about what shellholders you use, e.g. Lee shellholders are way too thick to work.

@Cigar do you know which ones work best with it? I think mine are Hornady

Originally Posted by stagstalker

@Cigar do you know which ones work best with it? I think mine are Hornady

Lyman definitely work, I bought a Hornady set recently and I think they were a little bit too thick (as you have found), I'll wander out to the shed and have a look.
I just keep my Lyman shellholder with the priming tool, and the Lee and Hornady ones get used with the dies.

I had a bit of a play in the shed.
Hornady shellholder on Lyman priming tool, noticeably larger hole, and plunger reaches flush at best. Shellholder 0.385 inches thick (bottom to where face of case sits).

Lee shellholder, marginally better than Hornady? 0.365 inches thick.

Lyman shellholder, plunger goes well beyond flush. 0.353 inches thick.

I use the RCBS hand primer, always works sweet, it has really good feel, it always seats them fully home and you can keep squeezing a little bit to get a small amount of crush/preload on them, id never be happy with a flush primer, im after seated below the base of the head, so you can feel it with your finger

Awesome thanks Cigar

Originally Posted by tikka

This is my favourite tool in my reloading arsenal.
Stainless Steel Priming Tool

I was looking at one of these myself (or the K&M model), but they look fiddly as hell! Do you have any feedback on how quickly they can be operated?