Funky superbolt wear?

[Load SM5]

Maybe this should be in tech but...

Up until today my superbolt was wearing pretty evenly. After random people put 7000+ shots through my gun at Mardi Gras it still looked pretty good. After today, though, I noticed that it had small deep furrows cut into it, all the way around running about half the length of the bolt. And a few small chunks were missing. Can anyone explain this? I honed the sharp edge off of my spring when I first got the gun so that can't be it.

Also I when I first got to the field I went to the chrono expecting to only have to make a small adjustment either way. Instead my mag was shooting around 185. A few turns of the adjuster and it shot fine all day but I was wondering if there was a way my velocity could have turned down without me doing it. Unless Tom messsed with it at Mardi Gras ;) it should have been shooting around 285 like it was the weekend before.

All that aside, I had a great day today and still madly love my SFL. My wife is so jealous.

[Russ]

Is there a small burr around the breech? When you say "half the length of bolt", it makes me think that there must be something, perhaps on the feed tube that is scratching the delrin? Maybe the ball detent?

BTW, does your superbolt have the foamie? Mine does and so far, so good.

Russ, just guessing :)

[Load SM5]

Well, I found the problem, at least with the velocity... There's a ring that is threaded into the breech that the bolt spring is braced against. Mine had unscrewed a few turns, causing the spring tension to go down along with my velocity.



It also looks as though the extra ball detent may have pushed a bit of the feed tube onto the the breech and caused the wear. I'll look into that.

[Drizit]

that shouldn't have caused the velosity drop, the spring only returns the bolt. it doen't affect the velosity like it does on a blowback.

[Load SM5]

Arg, your right. That's why I don't do this for a living.