[macv]

Hi Shooters
I now have about 2500 rounds through my GM brl. and have developed a gray mark at the 10 o'clock position on the brl.. I can't remove this mark with bore clnr.,sweets, or even jb paste. When I use bore clnr. on a Q tip and rub this spot, the q will turn black but the mark will not come off. I don't know if it is lead buildup or heat that has caused this mark. Is it possible that the bolt is not sitting squarely against the brl. and maybe gases are being expelled at this area to cause this mark? Has anyone ever experianced this problem? Thanks for looking. By the way, the buildup is not thick, it's just there.



Todays sighters are better than yesterdays zero's

 

[106]

Gray Mark

macv,

I am assuming that this is a 'blued' GM barrel, and that the "gray mark" is on the breech face....? ?

If so, it is a combination of the bolt / breech contact and powder fouling...! ! Not to worry...! !

When firing my S&W K-22 revolver, the forward face of the blued cylinder gets a ring around each chamber; this is a combination of powder fouling and leading...! !

Remember, the 10/22 is a "blow back" action: the recoil and hot gasses of firing a round push the bolt rearwards, and as soon as the mouth of the case clears the chamber, the powder gasses blow out into the action; the returning bolt slams these gasses, and the debris they carry, against the breech face of the barrel, grinding the debris into the pores of the steel...! !

It is not a problem...! !

 

[macv]

Big Mike
Thanks for the explanation. And yes, it is on the breech of the brl.. It is not affecting anything at all other than just leaving a mark. Thanks again. :t