Ok, am I crazy?

[CRNA]

Ok, so loading my 7RM. I tried measuring the primer pockets. I use this side of my calipers.
working

And I put this end in the primer pocket like this.

And I get this number.

Then I measure a Fed215 (you can see it in the caliper), and it measures this.

Now, from all I have read, primers are supposed to be recessed into the pocket give or take about .004". If my measuring is right, then mine will ALWAYS be sticking out from the head of the case approximately this much. The whole reason that I tried doing this in the first place, was I noticed my primers seemed to be protruded. I measured 20 primed cases and wrote all the numbers down. Then I punched out the primers and remeasured. Sure enough, I found my case length shrank by........guess what.......about .004". What is going on? My primers appear to be too big for my brass. Is it me? Am I doing something really stupid here, or are my eyes and measurements agreeing that with this situation my primers will never go below flush the way they're supposed to ? Any insight would surely be helpful.

OH!!!! By the way, measured my large rifle primers and they were shorter. They would actually fit in my primer pockets, but after working up a load with them, found me ES went all over the place. (Really bad, like an ES of 70!!!) There's gotta be something that I'm missing here.

 

[Shooter264]

If you are using Winchester brass that is not an uncommon problem. Simple fix, get a primer pocket uniformer from sinclair and cut your primer pockets square at the bottom.

 

[SBruce]

IMO, We certainly don't want the primers extending out past the case head.

I don't think you're crazy, my Fed 215's measure .128 to .130 also. I only have one lot of them, so I don't know if that is normal for them to be that thick or not?

There is no protrusion from the heads of my 338 Lapua brass with these primers, but they are only flush to .002 below.

A primer pocket uniformer should solve the problem in your case I'd think. My Sinclair uniformer is .132" deep. If you don't want to go through that process, you may have to try some different brass.

 

[CRNA]

IMO, We certainly don't want the primers extending out past the case head.

I don't think you're crazy, my Fed 215's measure .128 to .130 also. I only have one lot of them, so I don't know if that is normal for them to be that thick or not?

There is no protrusion from the heads of my 338 Lapua brass with these primers, but they are only flush to .002 below.

A primer pocket uniformer should solve the problem in your case I'd think. My Sinclair uniformer is .132" deep. If you don't want to go through that process, you may have to try some different brass.

It looks like that's the way I'm headed. First I will get the uniformer and see what I can do with it. I was just tinkering with measuring when I found the protrusion problem. And I certainly agree with you, I don't want the primer out of that pocket at all as it would seem to be a very dangerous situation even with accidentally dropping a case. Thanks for the input.

I measured probably ten or fifteen of my 215s and I got the same number on all of them.

 

[MT4XFore]

Any thought about trying CCI 250's?

 

[CRNA]

Any thought about trying CCI 250's?

Well, I could try them I guess, but if they are the same size then I'm going to run into the same problem. I bought a thousand 215s so I guess I'll try uniforming the pockets and see if that helps.

 

[boomtube]

You aren't "crazy" but you're missing a part of the puzzle when you isolate and measure the height of a new primer; they don't stay that high. Observe the profile of a new primer and you will see that the anvil legs are proud of the cup edge by a few thou, that make's transporting and handling them a bit safer. There is no standard height for new primers, the makers can use all the anvil height they wish.

When we seat them - properly - the cup will bottom in the primer pocket, forcing the anvil in to slighly compress the priming pellet and increase firing pin sensitivity.

So, you're thinking but you need to fully seat the primers and THEN measure the cap height; it should be 3-4 thou below flush, you will probably be fine. If not, THEN it may be time to use a bit more seating pressure OR a pocket uniformer.

Your velocity spread probably came from a slightly low ignition temp for the type/volume of powder you're using, not the height difference. All powders burn most consistant in a proper peak pressure range and cooler primers may not get it up to where the burn will be good.

 

[CRNA]

You aren't "crazy" but you're missing a part of the puzzle when you isolate and measure the height of a new primer; they don't stay that high. Observe the profile of a new primer and you will see that the anvil legs are proud of the cup edge by a few thou, that make's transporting and handling them a bit safer. There is no standard height for new primers, the makers can use all the anvil height they wish.

When we seat them - properly - the cup will bottom in the primer pocket, forcing the anvil in to slighly compress the priming pellet and increase firing pin sensitivity.

So, you're thinking but you need to fully seat the primers and THEN measure the cap height; it should be 3-4 thou below flush, you will probably be fine. If not, THEN it may be time to use a bit more seating pressure OR a pocket uniformer.

Your velocity spread probably came from a slightly low ignition temp for the type/volume of powder you're using, not the height difference. All powders burn most consistant in a proper peak pressure range and cooler primers may not get it up to where the burn will be good.

You are absolutely right boomtube. I measured a new primer, primed a case, decapped it, and remeasured it and sure enough, it shrunk by about 2 thou. My pockets still seem to be a little shallow though. I may just try to uniform the pockets to get them to seat below flush. Thanks for the advise.