Weird marks on a GP100 forcing cone -help!

[Al Thompson]

Went shooting with a good friend today and he pointed out some weird marks on the end of his GP100 barrel. The forcing cone end has some nicks in the barrel almost like "reeding" on a coin. The nicks are not spaced completely evenly. They run along the face of the barrel, oriented up and down with the majority at the 11-1 position and 5-7 position.

He got the Ruger new, had some work done by a "name" gunsmith.

It shoots fine and has no excessive blow-by.

I checked the nicks with a knife blade and they are indeed nicks, visually they don't appear to enter the barrel, nor do they protrude to the exterior of the barrel.

He and I have never seen anything like this. Is it possible that the smith used a forcing cone reamer ( like Brownells sells/sold) and nicked the barrel?

Any thoughts would be appreciated.

Giz

 

[Greg All Calibers]

I too developed the exact same marks on my GP-100 forcing cone..... only after Ruger tightened up the cylinder (reduced the end-play)..... so that the cylinder now rides very close to the forcing cone. It used to have a larger gap.

So I can assume the smaller gap allow less gas to escape and the forcing cone has quickly developed this 'wear'.

Not sure if it's harmful, though.

Is there much back and forth (end-play) movement in the cylinder on the gun that you have?

Any comments from the experts out there?

 

[Al Thompson]

Greg, I'm not at all sure it's wear. Most wear marks from cylinder gap problems manifests itself in a groove being worn in the top strap.

End shake is minimal on his GP-100.

Wonder if there is a common tool that GP smiths use that leaves those marks?

Giz

 

[1goodshot]

I would take it to a gun smith that I trust and have them look at it,It's better to be safe,it might just need to smoothed up.