Below is a cut and paste of an thread I started on another forum in 2011 and how has passed 12,000 hits. Thought you guys might enjoy it and give you food for thought.
"I am now rethinking my rifle cleaning applications and this is what I found or other words this is the first in a series of The Carbon War Chronicles.
One of my target rifles I haven’t fired since 2005 was pulled out and given a once over to see how it is doing and in my gauging now I have added a muzzle gage (got it from CMP) and I inserted the gage in the muzzle and saw it went in a bit far so I put the borescope in and to my shock I saw a ridge of metal build up about 3/8” down inside barrel with a copper build up on it. I remembered last couple of times I shot it that the rifle was not up to par at 600 and this explained it so I decided to whack off 3/8” and get down below the damaged area.
Got it whacked off with cut off saw and started to insert in back of lathe and it there wasn’t enough room to get barrel in back of headstock with action still on so I looked at log book and it had 2800+ rounds on it and the borescope showed it was starting to get tired so I screwed the barrel off and cut off the barrel threads which is known as a “set back”. After rethreading and rechambering it was put back on.
Barrels get most of their wear in the throat about ¼” to ½” forward of the chamber so whacking off ¾” (length of the action threads) will get you into not new but nearly new rifling and remove the effects of high pressure flame erosion.
For years I have liked 26” barrel length to give me good sight separation for shooting long range. Target shooters well know the longer the barrel the further the iron sights are apart and the ability to aim is enhanced with a longer sight radius. This is why you don’t see many guys after age 40 shooting service rifle, especially the AR variety because the older shooter’s eyes won’t accommodate looking close and distant as well as younger shooters eyes will.
Bottom line here is service rifle is a young man’s game but the good news is the NRA Highpower Rules have been changed to allow one corrective lens to be used in rear aperture of a service rifle.
OK back to the set back barrel. To increase sight distance devices known as bloop tubes were developed by an innovative shooter named Scott Medesha which initially consisted of a machined block of aluminum and half of it clamped on the muzzle that was altered to remove taper and give cylinder dimensions about last 2” of barrel.
In the other end of the block a piece of aluminum tubing is inserted which in effect does not lengthen the barrel but the distance between the sights can be enhanced up to a foot. Cap Screws pull the block (slotted in bottom) together and it holds the sight radius extension as the front sight is then placed on front of the tube.
I did not need a foot so I turned the muzzle to .850 and got a piece of stainless steel pipe about 3” long and bored the inside of it to .850”. I drilled and tapped the pipe for the front sight base and then I carefully fitted them together so the front sight was vertical and when it was right tapped it home so now I have a .850” hole at front of barrel and a slightly longer sight radius.
I fired it 20 rounds and the interference fit remained snug and did not move and after confirming the front sight was in the right place I drilled a hole through pipe and into barrel and put a set screw in.
I rechambered the rifle with the same chamber reamer it was put on with in 1990 so all my cases previously fired in first chamber fit the new chamber perfectly so I did not have to pull down the ammo I had loaded for it several years back. On each target rifle I have 200 to 500 pieces of brass that are only fired in that rifle and the boxes are identified by the serial number of the rifle to keep them segregated.
It is a very tight chamber and brass barely moves. Thusly when run into FL die the brass is barely moved returning it to reloadable dimensions. I can reload and fire brass in this chamber using LC Match cases over a hundred times by stress relieving the necks every three shots and cleaning the brass well.
THEN IT HAPPENED ! ! ! ! ! In life you think you know all the answers when you get older but next thing you know all the questions are changed ! ! ! !
It appears I have sort of created a problem in that when the bullet exits the muzzle the gases do not freely go off to wherever but they deposit carbon (our worst enemy besides politicians) on the inside of the tube and the face of the barrel. I zeroed it at 200 yards with iron sights and made an interesting discovery.
I knew that carbon got hard when it cools and never could figure out how quickly this occurred until this past week when I finished the zero session and cleaned it within a few minutes I had ER in the muzzle and the carbon came out rather quickly and easily. I figured if the carbon remained in a heated condition it would remain soft but then again the internal temp of cases run around 3000F and cooling them off to about 120F was too much to hope for. I thought I was good to go until I went to a high power match over the weekend and fired 88 rounds.
We only had three relays so the barrel never cooled off and I ran ER on a bronze brush through it about 30 passes after 66 rounds when we left the 300 yard line and went to 600 yards and shot 22 more followed by another cleaning. I estimate the barrel got to about 130-140F during the rapid fire stages and never cooled down below 115F all day.
I noted a goodly amount of carbon build up on muzzle so I left the range with a patch soaked down with ER packed in against the muzzle in what I THOUGHT would be the thing to keep the carbon wet and soft.
I got home and did not get to look at the muzzle again till Sunday afternoon and to my shock when the soaked down patch plug was removed the carbon was STILL HARD and there was build up adjacent to every groove and I inserted a scraping tool and it was too hard to scrape off. So basically the ER soaked it for 24 hours had not kept it soft.
I next tried Mobil 1 Synthetic Motor oil as I know it keeps the internal parts of my engines very clean so I soaked another rag plug with Mobil 1 and left it 6 hours and the carbon came right out with a minimal of scraping.
Went out and ran some testing and fired another 35 rounds and laid the Mobil to it again and it cleaned right up.
Bottom line here now is I will be doing more work along this line in the Carbon Wars to see which tactic works best. I also have some other stuff that is advertised to be a carbon remover and will try that as well but it is extremely expensive for a quart of it and Mobil 1 is like 6.35 a quart. I will try some other things as well but the traditional stuff has never seemed to work in the past.
Bottom line here is if carbon is this hard to remove from the muzzle you can just imagine it loading up inside the barrel round after round and that is a much longer surface to deposit on and it if builds up and packs hard at the muzzle just imagine what is happening inbore as additional rounds go downrange."
"I am now rethinking my rifle cleaning applications and this is what I found or other words this is the first in a series of The Carbon War Chronicles.
One of my target rifles I haven’t fired since 2005 was pulled out and given a once over to see how it is doing and in my gauging now I have added a muzzle gage (got it from CMP) and I inserted the gage in the muzzle and saw it went in a bit far so I put the borescope in and to my shock I saw a ridge of metal build up about 3/8” down inside barrel with a copper build up on it. I remembered last couple of times I shot it that the rifle was not up to par at 600 and this explained it so I decided to whack off 3/8” and get down below the damaged area.
Got it whacked off with cut off saw and started to insert in back of lathe and it there wasn’t enough room to get barrel in back of headstock with action still on so I looked at log book and it had 2800+ rounds on it and the borescope showed it was starting to get tired so I screwed the barrel off and cut off the barrel threads which is known as a “set back”. After rethreading and rechambering it was put back on.
Barrels get most of their wear in the throat about ¼” to ½” forward of the chamber so whacking off ¾” (length of the action threads) will get you into not new but nearly new rifling and remove the effects of high pressure flame erosion.
For years I have liked 26” barrel length to give me good sight separation for shooting long range. Target shooters well know the longer the barrel the further the iron sights are apart and the ability to aim is enhanced with a longer sight radius. This is why you don’t see many guys after age 40 shooting service rifle, especially the AR variety because the older shooter’s eyes won’t accommodate looking close and distant as well as younger shooters eyes will.
Bottom line here is service rifle is a young man’s game but the good news is the NRA Highpower Rules have been changed to allow one corrective lens to be used in rear aperture of a service rifle.
OK back to the set back barrel. To increase sight distance devices known as bloop tubes were developed by an innovative shooter named Scott Medesha which initially consisted of a machined block of aluminum and half of it clamped on the muzzle that was altered to remove taper and give cylinder dimensions about last 2” of barrel.
In the other end of the block a piece of aluminum tubing is inserted which in effect does not lengthen the barrel but the distance between the sights can be enhanced up to a foot. Cap Screws pull the block (slotted in bottom) together and it holds the sight radius extension as the front sight is then placed on front of the tube.
I did not need a foot so I turned the muzzle to .850 and got a piece of stainless steel pipe about 3” long and bored the inside of it to .850”. I drilled and tapped the pipe for the front sight base and then I carefully fitted them together so the front sight was vertical and when it was right tapped it home so now I have a .850” hole at front of barrel and a slightly longer sight radius.
I fired it 20 rounds and the interference fit remained snug and did not move and after confirming the front sight was in the right place I drilled a hole through pipe and into barrel and put a set screw in.
I rechambered the rifle with the same chamber reamer it was put on with in 1990 so all my cases previously fired in first chamber fit the new chamber perfectly so I did not have to pull down the ammo I had loaded for it several years back. On each target rifle I have 200 to 500 pieces of brass that are only fired in that rifle and the boxes are identified by the serial number of the rifle to keep them segregated.
It is a very tight chamber and brass barely moves. Thusly when run into FL die the brass is barely moved returning it to reloadable dimensions. I can reload and fire brass in this chamber using LC Match cases over a hundred times by stress relieving the necks every three shots and cleaning the brass well.
THEN IT HAPPENED ! ! ! ! ! In life you think you know all the answers when you get older but next thing you know all the questions are changed ! ! ! !
It appears I have sort of created a problem in that when the bullet exits the muzzle the gases do not freely go off to wherever but they deposit carbon (our worst enemy besides politicians) on the inside of the tube and the face of the barrel. I zeroed it at 200 yards with iron sights and made an interesting discovery.
I knew that carbon got hard when it cools and never could figure out how quickly this occurred until this past week when I finished the zero session and cleaned it within a few minutes I had ER in the muzzle and the carbon came out rather quickly and easily. I figured if the carbon remained in a heated condition it would remain soft but then again the internal temp of cases run around 3000F and cooling them off to about 120F was too much to hope for. I thought I was good to go until I went to a high power match over the weekend and fired 88 rounds.
We only had three relays so the barrel never cooled off and I ran ER on a bronze brush through it about 30 passes after 66 rounds when we left the 300 yard line and went to 600 yards and shot 22 more followed by another cleaning. I estimate the barrel got to about 130-140F during the rapid fire stages and never cooled down below 115F all day.
I noted a goodly amount of carbon build up on muzzle so I left the range with a patch soaked down with ER packed in against the muzzle in what I THOUGHT would be the thing to keep the carbon wet and soft.
I got home and did not get to look at the muzzle again till Sunday afternoon and to my shock when the soaked down patch plug was removed the carbon was STILL HARD and there was build up adjacent to every groove and I inserted a scraping tool and it was too hard to scrape off. So basically the ER soaked it for 24 hours had not kept it soft.
I next tried Mobil 1 Synthetic Motor oil as I know it keeps the internal parts of my engines very clean so I soaked another rag plug with Mobil 1 and left it 6 hours and the carbon came right out with a minimal of scraping.
Went out and ran some testing and fired another 35 rounds and laid the Mobil to it again and it cleaned right up.
Bottom line here now is I will be doing more work along this line in the Carbon Wars to see which tactic works best. I also have some other stuff that is advertised to be a carbon remover and will try that as well but it is extremely expensive for a quart of it and Mobil 1 is like 6.35 a quart. I will try some other things as well but the traditional stuff has never seemed to work in the past.
Bottom line here is if carbon is this hard to remove from the muzzle you can just imagine it loading up inside the barrel round after round and that is a much longer surface to deposit on and it if builds up and packs hard at the muzzle just imagine what is happening inbore as additional rounds go downrange."
