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Copper fouling in a rifle


I have a 30/06 that will shoot 1" or less @100 yds but after the 10th shot my groups start to open up. I'm shooting Fed. Prem. 165 gr SBT out of it. I notice that everytime I take it out which sad to say is only twice a year. The barrel is fouling up with copper. While I know this is normal to some extent. Should it be doing it after 10 rds. to the point of affecting the groups? I have been cleaning it with Tipton's truly remarkable bore cleaning solvent and it will take me over an hour of swabing the barrel to get out the copper. Oh I found out the hard way that if your going to use this type of solvent you'd better use brass tools with a carbon fiber rod or it will eat the plating off whatever it comes in contact with over time. Anyone have any clues?

Might be something else besides copper...

I have heard of barrel temp though.

Check it out, more at link this is just the intro..

 Unless you're a guaranteed one-shot hunter, barrel heat will affect your accuracy. With the right data, however, barrel thermodynamics can actually work in your favor.

Generally, four classes of conditions exist within a rifle receiver when firing numerous shots. The first condition occurs when several shots are fired very quickly -- little heat can move from the barrel into the receiver.

The second occurs when several shots are fired very slowly, and a lot of heat moves from the barrel into the receiver, but overall cooling allows all parts of the gun to approach ambient temperature prior to each subsequent shot.

In the third condition, the first few rounds are fired in an ambient-temperature gun, which causes an intermediate rate of fire to exist in which the front-to-rear temperature gradient within the receiver becomes significant.

The fourth condition occurs during extended shot strings, at any particular (relatively constant) cadence, when the system eventually reaches equilibrium, so that, prior to each shot, both temperature and temperature gradient are essentially similar.


The only reason I post this, is my own account with my 7.65mm Mauser Bolt Action. After running through a couple of strings, 2 5rd stripper clips, the barrel is HOT when fired quickly.

My groups also "open" up not much but it is there. Wait for m25 , Ben will know more.

Just my .02 cents..

How fast are you shooting it?

As TW points out, barrel heat-up is a factor on sporter contour hunting barrels which causes shots to string out.
*Update: Got to thinking about your problem again, and since your rifle starts out shooting well and then opens up, I would lean heavily on the barrel heating or either tension from the stock being a major culprit. I'm scratching the noggin on it. I found some info (below) on cleaning and fouling from two different barrel makers.

If you let it cool completely between each shot, does it still open up after 10 shots?

Is the barrel floated off the stock?

As to the fouling, if you know someone with a bore scope, take a look in the barrel. Ten shots should not come anywhere near fouling a clean barrel. My good friend (long range competitor) regularly fires over a hundred rounds from his .308 between cleanings. His gunsmith on his competition rifles says that a little copper build-up can actually help smooth out some barrels and sometimes a barrel can be "too clean" (him not me saying this). It sounds like yours may have some tooling burrs or excessive roughness causing it to "load up" way too soon. You might try running some JB Bore-Bright through it a few times and see if that helps to polish it up a bit. I use it on all my rifles to clean and polish the first cleaning. Just don't use it every single time because it is abrasive.

As TW said, M25 can get way more technical on the subject (I don't type as good as I talk face-to-face  ;) ).

From Shilen:

How clean is clean?
We get this question many times and have a great deal of difficulty helping some customers understand that a rifle barrel does not have to be spotless to shoot great. Many times more harm than good is done in trying to get it that way. Picture a car's fender. If the fender has a small dent in it, then professional application of body putty fills the dent. When painted over, the dent becomes unnoticeable, and the surface of the fender is smooth and consistent. The same thing happens in a rifle barrel on a microscopic level. Removing this small trace of copper puts you right back to square one. The next bullet that crosses that area will, again, leave a small trace of copper. Similar to patching a pothole. All successful benchrest shooters shoot one or more "fouler" shots down the barrel before going to the record target. This is not to warm up the barrel. They are resurfacing it on the inside. Benchrest shooters clean between relays to get the powder fowling out, not the copper. However, since copper usually comes out with the powder, they know that it must be replaced to get "back in the groove". I've had shooters tell me they "cleaned their rifle for 3 hours to get all the copper out of it." Their next statement is almost invariably that they had to shoot 4-5 rounds through it just to get it back to "shooting" again. This tells me that in order for the rifle to shoot well again, they had to replace the copper they worked so diligently to remove. I have a 7x08 Improved that shoots the same 1/2" MOA after 15 minutes of cleaning or 3 hours of scrubbing and de-coppering. Personally, I prefer shooting to cleaning. The gist of this is to set a regular cleaning regimen and stay with it. If the accuracy of the rifle is acceptable with a 15 min. cleaning, why clean longer? I would much rather have people admiring the groups I shot than marveling at how clean my barrel looks on the inside.

From Lilja:
It is important to break-in a barrel though. The jacket material must be removed after every shot during the initial few rounds. If this isn't done the areas of the barrel that fouled will tend to pick up more fouling and it will build on itself. It is important to get a layer of powder fouling on top of the lands & grooves. This hard deposit will prevent the copper from stripping off the bullets. However, if the internal finish of the barrel is too rough the barrel will never be completely broken-in and fouling will always be a problem. Some barrels can't be broken-in.

A similar phenomonon can exist if the shooter uses an abrasive-type cleaner too often. The abrasives are very effective at removing all traces of both powder and jacket fouling. I mentioned that a barrel can be too smooth. The abrasives can get a barrel too clean as well and in effect the shooter is rebreaking-in the barrel again every time he cleans. This can end up in the dog-chasing-his-tail scenario. The shooter thinks the barrel is a fouler, as evidenced by the copper accumulations in the barrel. He works hard at removing the copper, resorting to using an abrasive cleaner. But when he does he removes the desirable layer of carbon fouling left by the powder and exposes fresh steel ready to grab some more copper off the bullet on the next shot. The cycle repeats itself. Like the dog the best way out is to go lay down and take a nap.

Also, as a side note....If cleaning with copper solvent that is ammonia-based, clean with water and oil it really well. The ammonia can become corrosive and pit the hell out of a barrel really fast.


--- Quote from: PegLeg45 on September 23, 2009, 12:16:20 am ---Also, as a side note....If cleaning with copper solvent that is ammonia-based, clean with water and oil it really well. The ammonia can become corrosive and pit the hell out of a barrel really fast.

--- End quote ---
Thanks. I do clean the barrel after using the copper solvent. The smell of the copper solvent is a whole lot worse than our 17 yr. old cats urine. That in itself is a wake up call to make sure the barrel is well oil after cleaning. As far as how fast my shots are. They are not rapid by any means in fact my 3 shot groups takes about 10 mins to do and after 6-10 rds I will put the rifle in the rack to cool, That will depend on how warm to the touch the barrel is. After 3 shots if the the barrel is too warm I wait till it cools. It just seems to me that my groups should not open up that quick Only shooting 3-3 rd groups for a total of nine rds in an hour or so. The barrel is free floating. I've had it since 1980 and have shot 500 rds through it so far.


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