M*CARBO Brotherhood

Bolt sketching pattern

Anyone have this marking? First time i pulled the bolt to clean, it was hard to get out. Cleaned it and the tube, even ran a 12g brush down through, but still getting this scoring. I can’t find any spurs or rough spots that would cause it.

Geez that looks crazy!

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My guess is the tube got pinched. I remember from band using a expander that took the dings out of my trombone slide but i don’t know if they make something big enough for this.

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@Gilligan369 I could understand a straight line scoring of the bolt but not a zig-zag pattern. I would try coating the bolt with some el-cheapo paint and inserting it carefully. Check the bolt for scratches and use a strong light to look inside the tube for any paint buildup on a sharp edge. Get a dowel stick and wrap it with fine sand paper and go to work.


@Don68, thank you. That’s a good idea

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