Reloading some today - 9MM, ran into a new one

[M1A4ME]

I've started using Winchester 9MM brass for the 115 HP/Blue Dot loads.

Yes, already tested/tried/worked them up prior to loading a bunch (if 150 counts as a bunch - it does when you're using the electronic scale to weigh each charge).

Anyway, I needed a few more cases to finish out the last box so I grabbed some from the Win jug and resized them and then belled them.  Then I grabbed a box of small pistol primers and started putting primers in them with the Lee hand priming tool.

The very first one was harder than normal to seat.  I took a look at it and it looked fine.  The rest were going along okay for about 12 or 13 cases, then I ran into one where the primer went in way too easy.  I grabbed up a spare Lee primer punch and easily pushed the primer out of the case by hand.  I've never seen a pistol case get an enlarged primer pocket before but hey, who knows, right?  I tossed it at the scrap brass can and missed.  I figured I'd just pick it up later.

I grabbed another Win case and primed it, then another.  No issues.  Then I remembered the primer I'd pushed out of the empty and put it in position in the priming tool and placed another 9MM empty in the shell holder.  Holy cow!  That same primer when in that case way too easy.  I used the same spare Lee primer punch and pushed it out by hand.

Then it hit me.  Same primer, two different cases.  I got up and grabbed the previous 9MM case that had missed the scrap can and put it in the priming tool and that time the primer inserted with the normal amount of force.

Not a bad case - an OOS primer.  I set the primer down on the bench and pulled out two more to bring in the house to measure OD/height, etc. (my tool box is still in the mud room from the CZ Compact project and AR lower build a couple weeks back).  Then, of course, I went off and left the primers on the bench - measurements tomorrow.

Anyone ever run into a primer that was so small in diameter that it would almost fall out of a primer pocket?  In all my years of reloading this is the first one I've seen.  I'll be "keeping an eye" on the rest of that box, too.  I've used 600 out of that box of 1,000 with no issues.  Probably won't have an issue with the rest of the box either.  I hope.

Funny stuff, sometimes. 

[noylj]

Nope, but considering the pressure to make more primers over the last 8 years...

[drec]

Did you mic the bad primer and a good one, to compare it with?  If you did, I might contact the manufacturer and ask for the dimensions and tolerances they use for their primers. The loose primer was probably within their tolerances.

[1SOW]

What primer manufacturer?

[M1A4ME]

Primers were CCI 500.

The "small" one that I didn't trust staying in the primer pocket was measured multiple times (turned and measured several times to make sure I wasn't hitting a "flat spot" and measures with the jaws of the calipers both parallel and perpendicular to the primer cup.  I did the same with right sized primers.

Small one measured 0.1740" every which way I measured it.

Standard size (measured 2) was 0.1750" every which way I measure it.

Ten thousandths of an inch just made it a tad too small to insert (with normal force) and hold.  I can't say it would have fallen out in a magazine or when being chambered, but if it had then I'd have had a failure to fire and maybe additional feed/chambering issues from the primer in the magazine/action of the pistol.

As aggravating as that hand priming tool can be sometimes I don't think I'd have felt this on a press mounted priming system (then again, I've never used a press mounted priming system, so I can't be 100% sure).

[whitecap]

0.001 seems small but in this scenario it's big. That press fit is very important for retention and reliable ignition of the powder charge. Good catch. Even with the primer feed on my press, if I am able to detect a difference in the pull of the handle I am removing the casing and looking for something.



[Mods corrected subtraction]

[painter]

Am I missing something, or did they change the math again?

When I learned to add 0.174 and 0.175 is only a one thousandth difference...not ten

[nicky]

Painter, you are using "old school" math. 

[M1A4ME]

You're right Painter.  I should have either typed 1 thousandth or 10 ten thousandths.  The number was 0.1740 and I don't know if I can really trust a Harbor Freight electronic caliper to measure that accurately or not, but I typed the number in because I wrote it down

[painter]

 I wouldn't guess that a .001 undersized primer would be that loose. I guess I'll have to do some research on primer pocket specs.

[M1A4ME]

I've used one model or another of the Lee hand priming tools since back in the early 80's.  Wore a couple of them out.  The newer ones are made different (not necessarily better, in my opinion) but you get used to what it should feel like when squeezing that lever to seat the primer.  It was immediately apparent that one wasn't right.  I've seen (too) easily seated primers in .223 cases but it's always been because the primer pocket was enlarged.

The primer in this case wouldn't just fall out by shaking the case (like some of those .223 cases/primers) but I knew it went in too easy.  I could easily, using just my hands and a spare Lee depriming pin/punch just push it right back out.  I'm really not that strong.

[1SOW]

The number was 0.1740 and I don't know if I can really trust a Harbor Freight electronic caliper to measure that accurately or not, but I typed the number in because I wrote it down

Your right that the calipers can be off .001";  but consistently alternating between the two primers even if off on the reading should reliably tell you which is bigger or smaller.

I would have thought a "firm seat" would try to fill/spread in the primer hole .001".  Maybe not. CCI is the hardest USA primer.   Was the primer well below flush with the case?   

[M1A4ME]

I don't know if it was "well below flush".  It wasn't seated "out" where I could see it/feel it doing the normal QC (that was a slip of the fingers/mind - I meant to type QC and after the second finger stroke I saw CZ.)

It did go in "hard".  What I mean by that is you're expecting a certain amount of force will be required to seat the primer, then, when you squeeze it goes in really ease, which means it went in fast, too.  Going in faster means it hit bottom/end of travel harder than a normal primer being seated/inserted.

[1SOW]

With Winchester Cases,  you can SEE what ID calls the "moat"( ) around the primer---that is the bevel for the primer hole is visible and the primer can be seen to be down into that BEVEL.  With Win cases it's easy to see the primers are down below the case head.  (R&P has the biggest bevel,  and can be identified as R&P just by the bevel )

I've never loaded a CCI primer , so I can't speak for their seating characteristics,  but with a hard push on a turret press (like a single stage) it'll mash a primer in to fit edgeways.

[drec]

The SAAMI spec shows the primer dia dimensions of 0.1745" to 0.1765"; which could be bigger than the primer that you measured. The primer pocket dia dimensions are 0.1730" to 0.1745". So based on the tolerances, a 0.1745" pocket and a 0.1745 primer would be almost a slip fit. Then if you look at worst case you could have a 0.1730" dia pocket and a 0.1765" dia primer; which would give you a 0.0035" interference fit.

Refer to page 26, on the following for small primer specs

http://saami.org/specifications_and_information/publications/download/Z299-3_ANSI-SAAMI%20_CFPandR.pdf#page=10