- Thread starter db2000
- Start date
Can you accurately measure the bolt face firing pin orifice? It would also help to have the firing pin tip diameter, measured at around 0.050" from the end, if you can remove it from the primer.
I can give it a shot with my Mitutoyo’s.
Additional info should include I don’t have any issues with the same BCG and same primers in my .308 upper with Varget and Bergers or in 8.6 Blk upper with 300gr SMK and A1680. All Seekins. The 25CM upper did not always crater primers. I didn’t change reloading formula just seemed like it started one trip to the range, prompting buying the new firing pin after reading that may be the issue.
You sure that's the pin and not the primer anvil blown through the cup?
I bet you’re correct. It doesn’t make sense that 4 cases all look the same (just like your picture) because there couldn’t be enough metal lost from the firing pin to leave that much metal in every primer. It would be too short to even make it through the bolt orifice. Is that from a pierced primer?
Check the gas port for buildup.
Notice that the case in my pic, the dreaded 22 Nolser, doesn't show signs of pressure other that the pierced primer. Gas port stripped some copper from 88 ELDs and little pressure spike from bullet hitting port blew primer. Did a few before I noticed brass.
Notice that the case in my pic, the dreaded 22 Nolser, doesn't show signs of pressure other that the pierced primer. Gas port stripped some copper from 88 ELDs and little pressure spike from bullet hitting port blew primer. Did a few before I noticed brass.
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I checked gas ports and they’re open. The firing pin does seem to take on a lot of fouling with 25CM making its movement sticky compared to 8.6 Blk and .308 uppers I use the BCG in also. Cleaning everything causes less cratering and it gets worse the longer I shoot. The only change I’ve made from initially shooting the upper when it was first built was adjusting the SA AGB from bleed off to open a few full rotations as the brass was ejecting at 1 o’clock initially. May I added to much gas coming back. I’ll play with that.
Any additional thoughts appreciated.
Any additional thoughts appreciated.
What was temps at the range today? Were these the first 4 fired?
These were shot a few months ago. About 50-60 rds in on a new McGowan barrel. Maybe 60F max but likely colder as it’s winter in VA. Similar to other rounds. Same load and Lapua brass. Also tried new Alpha srp 25CM specific brass. Similar result without the metal sticking out. Deep craters though
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