Carbon ring?

[Wedgy]

That is only 300 rounds ??
Very nice view with the Lyman scope ! I have a Hawkeye but can't take photos or video

 

[The Oregonian]

That is only 300 rounds ??
Very nice view with the Lyman scope ! I have a Hawkeye but can't take photos or video

Yeah, I'd have to count but maybe 350, 400 tops. I haven't seen another barrel except my 6.5 Cr with similar rounds that has much less wear. The 280AI had a fast load of 3000 fps w/ 168gr but no pressure. It seems like here is a node from 2920 to 2940 so maybe that will help.

 

[tankgijohn72]

Thanks. The only area I am concerned with is the black area right behind what shows up as really bright where the chamber ends. Is that firecracking or is that likely a carbon ring?

Here is a video which might show this better.



What makes me think it could be a carbon ring is the difference in velocities I was getting over the last few days...like a ~60fps increase. Dates, temps, etc are on each chart. Unless noted, all seating depths are .020 off the lands.

View attachment 136825View attachment 136827View attachment 136826

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Your MV will increase over the first few hundred rounds, especially with anything overbore. I think the MV increase is mainly due to increased friction in the throat due to the fire cracking. If it was due to a carbon ring and you cleaned it out then you should be right back down to your starting velocity when the barrel was new, but i doubt it.