Doing some charge testing with a 300RUM and found a 87.5gr load of H1000 that shoots a single little ragged hole. Except the primer is leaving a ring on the bolt face. Fired primers look good and no other signs of pressure. Is this anything to be concerned with? How about case life, will this have a negative effect? Thanks!
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300RUM Primer Ring on Bolt
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wjm1000
Well-Known Member
How was the bolt lift? To me the load may be a little on the hot side, hard to tell for sure in the photos but it looks like the primers are flattened a little and the bolt face looks like it may be pitted a little from gas leakage.
If that ring is rough and pitted, it means that a casing leaked gas around the primer and those high pressure gases cut into your bolt face.
If there's no cutting, erosion, pitting into the face of the bolt, nothing to be concerned about.
It's impossible to tell by looking at your photo. Take a Q-tip and some bore cleaning solvent and clean up that ring. If after cleaning, you can see pitting of the steel bolt face thru a magnifying glass, you had at least one primer leak combustion gas and it torched your bolt face, cutting into the steel. This is normally caused by an over-pressured cartridge.
If there's no cutting, erosion, pitting into the face of the bolt, nothing to be concerned about.
It's impossible to tell by looking at your photo. Take a Q-tip and some bore cleaning solvent and clean up that ring. If after cleaning, you can see pitting of the steel bolt face thru a magnifying glass, you had at least one primer leak combustion gas and it torched your bolt face, cutting into the steel. This is normally caused by an over-pressured cartridge.
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your photo 34345.jpg shows cratering around the firing pin dimple. This shows that the pressure was high enough that some of the primer cup metal started to flow into the firing pin hole in the bolt. I saw this, with no other signs of pressure, for a guy at the range that had bought some foreign made primers when it became impossible to find primers. I think that for him the foreign primers used a softer metal in the primer cup thus allowing this condition at non-critical pressures. What brand of primers are you using?
I cleaned the bolt face as well as I could with a patch and Q tip. You can still see a ring shadow. But I can't feel any pitting or marking when I drag the tip of a needle across it?? Looking through a magnifying glass, it's so hard too see if there is any pitting. It's discolored, but if there is pitting, it's so small I can't clearly see it or feel it. Here's some more photos after cleaning it. I just don't want to damage the rifle at all as it's a hell of a hammer and I obviously want to stay safe.
Attachments
CCI MAG Large Rifle No. 250
I've etched a few bolt faces with excessively high pressure gas leakage over the years.
Your bolt face is in good condition, based on those two photos. I don't see any pitting caused by escaped gas.
Gas leakage there will erode (torch) metal from the bolt face. A little etching doesn't make the bolt unsafe or unusable. It would mean you'd want to back off the gas pedal with the load that caused the etching.
Your bolt face is in good condition, based on those two photos. I don't see any pitting caused by escaped gas.
Gas leakage there will erode (torch) metal from the bolt face. A little etching doesn't make the bolt unsafe or unusable. It would mean you'd want to back off the gas pedal with the load that caused the etching.
87.5gr H1000, New Norma case, CCI Mag 250, 220gr ELDX 0.02 off the lands.
I know book isn't firm, but I'm below book max.
I was taught a primer crater was a sign of pressure. I would load a couple of others - like Fed 215's if you can borrow a couple to try from a friend. The Fed 215 was specifically designed for the Weatherby cartridges.
