300wsm flat primers

[1993z28]

I have a new 300wsm. every load i try primer start to flatten 3 to 4 gr short of max load but no other sign of high pressure. Is this common with the 300wsm.

 

[Steve Blair]

Not with mine. What primer are you using?

 

[dkhunt14]

I never have that problem with any of mine. Are the primers sticking out of the case any? Are the primer pockets loose? Are you bumping the cases too much when you size? I think we need a lot more info. Matt

 

[1993z28]

I have new brass norma and remington primers are fed large rifle mag mach. the primers are not loose before or after firing. bolt opens very freely.

 

[Steve Blair]

New brass could be your problem as dkhunt14 noted above referencing bumping. Measure the base to shoulder difference between your fired and unfired cases. If it is more than ~.002", it is likely primer setback and not excessive pressure.

 

[1993z28]

Do you think the shoulder needs to be bumped to give more head space.

 

[Steve Blair]

No, it's too much headspace that might be the problem. What can happen is: [br]
The firing pin drives the cartridge forward against the shoulder.
The primer fires and pressure holds the case against the chamber walls, initially preventing rearward movement.
The primer extrudes to the rear until it contacts the bolt face.
The case now moves rearward, flattening the primer. [br]
Try the same charge with your once-fired cases and only bump the shoulder enough to easily chamber (~.001-.002").

 

[1993z28]

I do not think that is the problem i have so fed ammo when i chamber it the bolt smears the brass face and if i fire it i get a flat primer.

 

[Steve Blair]

Have you tried any reloaded cases?

 

[1993z28]

just new brass at time.

 

[dkhunt14]

Have you tried any reloaded cases?

New factory brass and loaded rounds are short on headspace so they fit all guns. Does the ejector pin have a super amount of tension on it? If it does it could be holding the cases front and causing the problem. It would also cause the smearing problem. What kind of gun is it? Matt

 

[1993z28]

stiller tac 30 action kreiger barrel.

 

[Elkbane]

Steve hit it on the head. EVERY time i use new brass in both of my 300 WSM's, I get slightly flattened primers, do to TOO Much headspace. Never happens on fireformed brass unless it truly is a result of pressure.

Elkbane

 

[AusFclass]

Depending on your rifle and bullet combo you might want to try a HARD jam with your seating depth to get your case back against the bolt for their first firing. I had a few 7 saum round's that wouldn't go off until I started jamming 40 tho with hybrids. They had about 7 tho head space clearance even though the smith cut the chamber to the go gage!

Might not be the problem with your rife but could be worth a try?