Carbon ring vs tight spot in bore?

[mattri]

Have a Krieger barreled 7mm-08 hunting rifle. Have had it for about 2 years now, has always shot very well, sub MOA out to 600 yards.

When cleaning this rifle I have been noticing a "tight" spot just in front of the chamber on the return stroke with a brush. Meaning that I run a brush from breach out beyond the muzzle and then back through the barrel and out. Don't notice anything on the "forward" stroke but coming back I feel resistance just in front of where I would expect a chambered round to sit.

First reaction was "carbon ring". But I have cleaned this rifle innumerable times using any and everything under the sun from #9 to KG1, Butches, Kroil etc.

Have used nylon and bronze brushes.

Have always run from breach to bore. Being a hunting rifle I have not used a bore guide but have used a coated Dewey rod, careful to keep in line with the bore.

Have run a brush from breach to bore and then pulled it back through the barrel, have also run a brush from bore to breach, un-screwed it and pulled the "empty" rod back through the bore.

After 10-100-1000 rounds I have always felt a "tight" spot just in front of the chamber on the back stroke.

Again- I have no complaints as to the accuracy of the rifle, it is everything I hoped for and more. Also doesn't seem to foul much if at all.

Just seems odd to have this "spot".

Thoughts?

 

[BoydAllen]

None of the cleaning materials that you are using will remove a carbon ring. You will need an abrasive cleaner, and will have to concentrate in the tight area. Depending on the barrel and the powder, you may be well advised to use an abrasive on a regular basis, but you will probably not have to use one every time that you clean. What does it being a hunting rifle have to do with using a bore guide? Given the value of the barrel, and the cost of a bore guide, not using a good one seems to be false economy, but that is just one opinion.

 

[338 Mollett]

Get a bore scope or find someone that does and have a look. That will be a good start .

 

[fdshuster]

mattri: Double what Boyd said. To get stubborn carbon out you must use JB bore paste (the original blue label, not the red) or IOSSO. Both do an excellent, fast job and I combine it with a good fitting (not lose) bronze brush.

You need the mechanical, scrapping action of the very, very mild abrasive paste with the bronze brush. I know some will disagree, but I have never found a liquid anything that will remove carbon.

Just gave 10 push strokes (chamber to muzzle only) with JB & a bronze brush to my 1-10 308 Tikka barrel. It did have some stubborn layers of carbon. It is now clean down to bare metal as verified with my borescope. It will now require 5 or 10 rounds to settle into its' usual sub MOA patterns, but I was able to verify that the throat is still in excellent condition at a documented 1203 rounds fired. A lot of life left in this one.

 

[Scott Harris]

IOSSO really is a great cleaner.....leaves the barrel sparkling like new and removes all carbon (with enough strokes )

 

[artbosco]

Use 3 to 5 Tight Fitting Patches of J-B Non-embedding Bore Cleaner, especially in that area, each and every time you clean.

The carbon will disappear and stay that way IF you're religious in your use of J-B.

I use it in my $500 barrels all the time.

 

[ShootDots]

Mattri, every one of these fellows are correct. First you really need to "borescope" it to actually SEE if you have an imperfection in the metal or if you have a carbon build up. Scrubbing and scrubbing will not get rid of a metallic imperfection. Now let's assume you have some carbon build up. When I first clean my barrels, I use a Sinclair nylon brush to get the carbon cleaner into the bore and loosen up SOME of the carbon. Then I take a wet patch (I use either Carb-Out, TM Solution or Bore-Tech Eliminator) (they all seem to work well) and push that patch thru to get the "excessive" carbon out. Then with one of those solutions, I get a bronze brush and go back and forth (all the way thru and all the way back thru) 10 times, re-soak the bronze brush and repeat. then I get another wet patch and push it thru.. Then I get my IOSSO "blue brush / very stiff nylon" and short stroke the throat and then you can "feel" this next step>> pull the blue brush half way into the bore and half way out at the chamber entry and "spin the brush" with your hands for several turns>>>this will really help in getting a carbon "ring" out of that area. Then I wet another patch and push it thru. Then get some "JB" and those "pellets" from Brownells and oil them up and push them thru, then "JB" OR "IOSSO" bore paste those pellets up and go thru the bore several times. Then put some more JB on the pellets and short-stroke the throat several strokes and then back and forth thru the barrel again. Clean ALL of the gunk out of the barrel and action. IF you had ANY carbon in there, it is now gone! I "JB" about every 300 rounds. BUT the "other" steps, I do ALL the time. Also, when you are NOT "JB"ing" let the carbon cleaner soak for 15 minutes or so>>>it does wonders in getting that carbon loosened up!

I know it sounds like a lot of work, explaining it took me more time than actually doing it! LOL!!!

 

[lpreddick]

i noted the same rough/tight feel when pulling a brush back and have borescoped these areas and found what i'm feeling is simply rough bore secondary to a lot of shooting. the bore is clean but the lands show a lot of firecracking as do the grooves. made a mark on the barrel where these were seen and noted where the brush got tight and that was it. polishing with abrasives seem to lessen the roughness a little, but it returns. the term "carbon ring" usually refers to the carbon deposit in the chamber just in front of the case mouth before the freebore begins. this carbon is baked on and has been discussed a lot on this forum. the only thing i'v found to reduce this rough feel is a ceramic-like product called Snipex. you coat the bore and bullet bearing surface and "fire lap" the bore. not sure this improves accuracy but does seem to smooth the bore.