7 Ultra Mag Not sealing on some shots

[ugsly308]

Im loading a 7 Ultra mag with 195gr Bergers. I get blow back like the case is not sealing properly and pushing the shoudler in on some rounds but 1 outa 3 will come out looking normal. Velocity is around 3,200 FPS. Ive tried loading them down and pushing them beyond max and still getting the same problem. Have tried Norma and Nosler (new unfired) brass also. Have any of you guys ran into this before?

Thanks guys,
​​​​​​​Casey

 

[Milo 2.5]

I can speculate here, most likely be right also, but post this in the gunsmithing section with ATTN in title. You need to quit firing it, you're so close to getting a face full of gas.

 

[MachoKing]

How deep are you having to seat the bullet?

 

[ugsly308]

We were able to resolve the issue. We got ahold of Berger and he mentioned that switching powders from Retumbo to 50BMG or US869 to get a 90% min fill case capicity would most likley fix it. Loaded some 50 BMG and the issue went away and rifle shoots very well. COAL at .010 off lands was 4.150", that kept the 195gr EOL bergers above the neck shoulder junction.

Thanks guys,
Casey

 

[Milo 2.5]

We were able to resolve the issue. We got ahold of Berger and he mentioned that switching powders from Retumbo to 50BMG or US869 to get a 90% min fill case capicity would most likley fix it. Loaded some 50 BMG and the issue went away and rifle shoots very well. COAL at .010 off lands was 4.150", that kept the 195gr EOL bergers above the neck shoulder junction.

Thanks guys,
Casey

Glad you got it figured, over my head, thought you had plenty pressure to seal it off. IME, most of the time you have dents like that, not sealing off, or way under pressure, but under pressure would not soot up the case rim.