I always hear other reloaders refer to primer flattening. Is that in reference to the edges of the primer or the area around the firing pin strike? I am wondering because some 10mm loads of mine had a flaatened rectangle around the the strike area. Is this due to the firing pin style of the particular gun or is it over pressure? Thanks.
Primer Flattening
- Thread starter clancy12
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snuffy
Member
Is it a Glock? If so, then it's the way the breech face is configured. The firing pin bushing is rectangular in shape.
Scimmia
Member
It's in reference to the edges of the primer. High pressure will force the primer against the breech face, flattening out the primer. It's more noticable on the edges where the primer rolls over.
gamestalker
member
When you resize and have the primers out take a close look at the to see if there is a small ridge that gives them a sort of top hat appearance. Top hat looking primers are a rather diffinitive sign of high pressure. I get top hat primers all the time, especially when I'm loading for my magnum wheel guns. Now and then I'll get a little over zealous with my 9mm and .40 cal. loads too.
1SOW
Member
'Some' primer flattening can occur in the press. If I get overzealous on my primer seating pull, the top of the primer can go very flat, especially with soft Fed SPPs..
amlevin
Member
What brand of primer. I notice that in my rifle loads Winchester Primers flatten even with near minimum loads. CCI's and Wolf look more like they should when using published loads.
243winxb
Member
Like Snuffy said. Normal for a Glock , if it looks like this.
This last picture isn't primer flattening. I call it ballooning. The primer has experienced higher pressures to cause the material to deform into the rectangular accomodation space. Edges though are still rounded. A flattened primer shows extrusion of the primer from the pocket and flat from edge to edge in the pocket. I loaded a .41 mag to heaviest loads I could and had a lot of flattened primers. You'd have to have a locked breech pistol to see that in an automatic. This ain't anywhere near that. It does remind me of ballooning I've seen in a blowback .380 shooting Buffalo Bore +P. Deformation around the primer strike.
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