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28 Nos Flat Primers

H

Hikinghunter

Well-Known Member
Joined
Dec 2, 2023
Messages
195
Location
Washington
All the primers I pop out of 28nos brass look like this. Factory ammo, reloads from the lower end to the top, doesn't seem to matter.

My 280AI doesn't do this. Is this just a 28nos thing? Wondering if this rifle needs to go back to the factory for a check-up.
IMG_4645.jpeg
IMG_4644.jpeg
 
fseaman said:
Have you measured fired brass vs resized?

If the primers are popping out something not right with a length somewhere.
Click to expand...
Brass shoulder isn't moving forward, or at least not more than a thou (my calipers are only so sensitive). Using Peterson brass. The primers are not loose or falling out, I'm removing them with a depriming tool. They are just flat, with that "nail head" look.
 
Are your primers being seated properly: slightly below flush with the base? Peterson brass has tight primer pockets so if your not seating primers below flush I don't think the firing pin strike would have enough force to seat it leading to the primer being partially extruded when brass starts to flow.
 
fseaman said:
Please show the firing pin side.

Please show the champher on your primer pockets.

What is your reload recipe
Click to expand...
Keep in mind that it's flattening primers for all factory ammo (nosler, hornady, Pendleton). So I don't think it's a load issue here. I'm wondering if this is just a thing with 28 nos. But here's a photo some fired handloads anyway.

No noticeable cratering.

Peterson Brass
WLRM primers
175gr Berger Elite Hunters
Retumbo (77.5 to 81 grains, makes no difference in terms of primer flattening).


IMG_0809.jpeg
 
Yes
tomcat818 said:
Are your primers being seated properly: slightly below flush with the base? Peterson brass has tight primer pockets so if your not seating primers below flush I don't think the firing pin strike would have enough force to seat it leading to the primer being partially extruded when brass starts to flow.
Click to expand...
yes. I test every one of them on a flat surface. Again, the rifle flattens factory ammo primers too. It's not a handload issue.
 
The primer second from left is super flat looks like over pressure the others have slight radius. If you have a camera with a flash take some in focus pictures (like below) of removed primers from factory next to handloads along with an unfired primer for comparison .

Also, what factory ammo? Nosler has a recall on their 28 Nosler ammo for exceeding max pressure.
 

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How deep are your pockets?
One of my 25-06 rifles does the same thing in all brass except Norma.
It actually has negative headspace by .001", so it's not excessive sizing. No matter what I do, what I measure, all primers come out with the 'top hat' look. I've had the rifle since 1989 and no one can diagnose the issue. Had another barrel fitted, same cartridge, same result…

Cheers.
 
Check how much you are setting the shoulder back when resizing. Knock the old primer out with a decapping die before you measure. Try resetting the sizing die so it gives you the same size as before you sized it. And of course, try it in the rifle before primers, powder and bullets. You should feel a very light drag on the case head when you close the bolt when you are sizing to the exact chamber spec on your rifle. If you can field strip the bolt by removing the firing pin assembly, all the better.
 
Last edited:
MagnumManiac said:
How deep are your pockets?
One of my 25-06 rifles does the same thing in all brass except Norma.
It actually has negative headspace by .001", so it's not excessive sizing. No matter what I do, what I measure, all primers come out with the 'top hat' look. I've had the rifle since 1989 and no one can diagnose the issue. Had another barrel fitted, same cartridge, same result…

Cheers.
Click to expand...
Has anyone checked the bolt face to make sure it is flat and not dished especially in the area where the primer makes contact?
 

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