while doing my year end clean up of my 50 cal M/L I noticed in the barrel about 2 inches above the breach plug there is some build up, looks like powder residue, I brushed it, still there, I soaked it with cleaner, still there, put two patches onand ran them thru, its still there.

Any suggestions on how to clean it without hurting the twist/grooves?

thanks,
John

Are you sure it is powder or is it possibly a stain. Perhaps some of the powders you use, or the breech plug grease made this happen. If you scrubbed it with a good solvent and it did not come out, and then oiled it, I really do not see anything more you can do.

could polish it with JB Bore Paste - just don't get too carried away.

I had the same problem above the breech plug in my old gun. It took lots of cleaning to get it out. I can't offer any suggestions other than clean it well and if it's still there you'll have to give up. I had mine for a while but it finally wore off.

bowhunterjohn

I really think Cayugad's explanation of BP grease staining is a real possibility. I used to use BP grease, a grease with aluminum in it and one with copper... I really had a hard time getting the copper out of the pores and I could see it just fine.... It did finally disappear after I quit using grease.

Same thing happened the first time i fired my Encore. Used Jim Shockey's Gold. About three inches at the breech had this awful hard crud. Nothing, including Windex with vinegar, would get it out. Finally got out the .50 caliber bore brush and gave it a couple of good scrubbings with Hoppe's barrel scrubber. This got it out.

If you are shooting Tripple Seven you may be getting the same crud ring that I get in my Omega. I had a h%%L of a time removing it from my rifle. Some claim it comes out with water; but not in my rifle. I had to use a bore brush and gun scrubber and finally JB bore paste to get all of it out. Needless to say I don't shoot Tripple Seven in the Omega any more.