Want that erratic gun to shoot right again? Then follow our rigorous—but ultimately effective—bore-swabbing regimen.


There is no single factor that affects accuracy more profoundly or is neglected by more shooters than proper bore cleaning. Bore fouling is the number-one reason that previously well-behaved rifles suddenly start to shoot poorly. I have a .338 Winchester Model 70 rifle that contributed a great deal to my increasingly gray hair. It was once a fair shooter, but it slowly went sour after a long summer of load development and testing. I rebedded the action and recrowned the muzzle. I tried every trick I knew, but nothing would help—including what I thought was proper cleaning. In the end I ran it through the Outers Foul Out electronic cleaner for 13 cycles (using the method detailed below) before it finally showed clean at the start of the cycle. I combined this with lots of work with a rod and good solvents until there was no doubt that all fouling was removed. It took a very long time and a lot of work, but in the end, it was worth it. That rifle went from shooting 4-inch groups at 100 yards to a 1.5-inch rifle with that cleaning.

What I eventually learned about the rifle was that its bore was not all that good to start with (it is rough), and it quickly fouls. When that happens, accuracy takes a nose dive. I had been cleaning it regularly during the load development process, but never completely. The fouling accumulated over time. This was, no doubt, compounded by shooting a lot of Barnes X-Bullets and early Winchester Fail Safe bullets. Both use relatively soft, ductile metal which has a tendency to cause more fouling. The point is that there wasn’t a thing wrong with the rifle. No rifle will shoot well with a badly fouled bore.

Though I am convinced that small amounts of fouling dramatically affect a rifle’s performance, I wondered if I could quantify just how accuracy went to hell when cleaning wasn’t conducted properly. So I recently tested the effect of fouling on accuracy with two Remington rifles wearing stainless-steel barrels. My results show how relatively few rounds can denigrate a rifle’s performance.

I realized, however, that even if I convince you that fouling is fouling up your rifle, you may not know how much effort and technique is involved in getting a bore truly clean. Below, then, are cleaning solutions I know work because I’ve seen the results they deliver. If you employ them, you’ll most likely see improved accuracy in your centerfire rifles.

Accuracy Testing
To see how fouling affects centerfire rifle performance, we shot a series of three-round groups at 100 yards with factory loads. We logged and recorded the results on a group-by-group basis in the accompanying table and graph.

The shocking truth is this: Some guns may begin shooting erratically after just a few rounds have fouled the bore. For example, in our tests, a Remington Model 700 7mm STW shot Remington 140-grain factory loads very well for only two groups (six rounds). The first group logged in at 0.85 inch, the second was also under MOA at 0.98 inch. The third group, in contrast, ballooned to 1.8 inches. After another six groups, the gun was shooting about 3 inches. Then, after cleaning, it dropped back down to 0.95 inches.

This experience parallels the results we recorded for a Remington Model 7 in the new .260 Remington. Also shooting factory loads in this gun, our first group measured 0.72 inch, followed by two more good clusters of 0.98 inch and 1.10 inches. Thereafter, accuracy took a nosedive, dropping to 1.68 inches. The next few groups were even worse, ranging between 2 and 3 inches. After cleaning, the gun dropped back down to the 1-inch range.

We realize that most shooters know their guns need to be clean to shoot at their best, but we doubt that most gun owners know how quickly accuracy can suffer and to what extent performance can degrade. Furthermore, we think most recreational shooters may not understand how to get a bore truly clean. It’s not enough to run a patch through the bore a couple of times. All the metal and powder fouling needs to be removed, and that takes a lot of effort. Below, we detail one regimen that will produce a clean bore and help you get the most accuracy from your rifle.

Detailed Cleaning
The key to cleaning the bore is to do it properly and often. It’s easy to come in tired from a long day of shooting or hunting and just run a patch or two through the bore, or often do nothing at all. That just won’t cut it.

Even if you think you have cleaned the barrel, chances are that you have not done it correctly or completely. Usually, at best, the end of a shooting session will find most of us simply passing a few solvent-soaked patches through the bore and thinking we have things under control. The truth is that a fouled bore is tough and time consuming to clean properly. Fouling is a cumulative problem, and each time we fail to clean properly, the fouling is compounded until the rifle finally rebels.

Any rifle will react to fouling, but the typically smaller bores of today’s popular rifles are particularly susceptible. In a smaller bore a given amount of fouling affects a larger percentage of the surface area of a bullet that passes through (as opposed to bigger bores), and accuracy can deteriorate quickly and drastically.

Guides, Rods, and Cradles
If it’s possible, always clean from the breech and use a rod guide. The best guides not only keep the rod aligned with the bore, but also protect the action from dripping solvent and crud from the bore. Bore guides also make it much easier to start a patch and to apply solvent to the patch. Stoney Point has three models, one of which will work with most bolt actions and single shots on the market. Dewey also offers some that are caliber specific.

Some rifles such as pump actions, lever actions, or semiautos must be cleaned from the muzzle. If you can’t clean from the bore, at least use a rod guide to protect the crown from cleaning-rod wear. Also, put a rag in the action to catch the crud you push out of the barrel. Rod guides for the muzzle look a little like a funnel. The tapered outside is designed to fit into the muzzle, while a hole through the center the same diameter as the rod will keep it centered and prevent contact with the crown.

The best cleaning rods are one piece, either hardened steel or plastic coated. Some shooters believe a hard-steel rod will not pick up grit and become a file as it runs down the bore. Other shooters prefer a coated rod because they believe that as a rod flexes inside the bore, a steel rod will continuously hit the barrel at the flex point and damage the rifling as it pushes the patch through. Most precision-oriented shooters we’ve encountered use coated rods. Dewey offers a selection of coated rods. Regardless of which you choose, be sure to wipe the rod often with a clean rag to keep grit from accumulating.

It is always best to hold the rifle in a cradle. For a work bench it is hard to beat the Decker Gun Vise. Midway also offers a range box that serves for a multitude of chores in addition to carrying gear for the range. The box comes with a complete set of cleaning tools as well as a built-in cradle to hold the rifle. The MTM Gunsmith’s Maintenance Center will hold the rifle for cleaning as well hold a lot of tools and chemicals. Those shooters who already have one of the ubiquitous MTM Shooter’s Boxes might consider the Portable Rifle Maintenance Center that will fit on top of the box for field cleaning.

Solvents and Their Application
It’s out of the scope of this article to compare solvents, because it is our opinion that even the best solvent poorly applied won’t do the job. That said, we like and use Outers Super Solvent or the Shooter’s Choice solvents. To apply them properly, make several passes through the bore with a fairly tight patch well soaked with solvent. Use each patch for only one pass through the barrel, replacing it with a new solvent-soaked patch after every pass. You may want to let the gun soak a few minutes between passes to allow the solvent to work. Outers has a new foaming solvent that stays in contact with the entire bore surface instead of running to the bottom.

Now use a properly-fitted bronze brush soaked with solvent and make several passes. Bronze is the best brush material, in our view. Nylon doesn’t have the scrubbing ability of bronze, and a stainless-steel brush can gall and ruin the barrel very quickly. Keep the brush wet with solvent, reapplying after every couple of passes. Follow with one wet and several dry patches to remove all traces of solvent. Always remove the solvent from your brush after use with a spray such as Outers Crud Cutter. This is to prevent abrasive debris from accumulating, and because some solvents will eat the bronze bristles away.

Now scrub the bore with a patch and a good copper solvent such as Barnes CR-10, Shooter’s Choice Copper Remover, Outers Super Solvent, or Hoppe’s Bench Rest Copper Solvent. Be sure to read the instructions on the label; these are harsh chemicals. Some should not be left in the barrel for more than a few minutes, others should not be mixed with other solvents. Let the bore soak for a few minutes and follow with another wet patch. When you have patches coming out white with no trace of green or blue (it may take a while if the fouling is extensive), dry the bore with several clean patches.

Next, scrub the bore with the general solvent again using patches and brushes. Then dry and repeat the copper solvent treatment. Sometimes metal fouling can be trapped under layers of baked-on powder fouling that you must remove to allow the copper solvent to get at the metal fouling. Keep repeating this process until you have no sign of blue or green on any patches used with the copper solvent.

If you wish to simplify this process, you can use the Foul Out Electronic Cleaner from Outers. This device uses an electric current to activate a reverse plating process that removes the bore fouling and deposits it on a metal rod, speeding up the process a great deal. Use the Electronic Cleaner like you would the copper solvent. After the patch and brush treatment with the bore solvent, wipe the bore clean with several dry patches and finish with a patch wet with Outers Crud Cutter or similar product to remove all traces of oil or solvent. Rubbing alcohol works fairly well in a pinch. Always sand the rod and clean it with Crud Cutter or alcohol before inserting it in the barrel. This creates a clean metal surface with no oxidation or oil to prevent the current from flowing properly.

Run the electronic cleaner until it indicates a clean barrel. Dry the barrel with a clean patch, then run a patch wet with bore solvent followed by a brush that is well saturated with bore solvent and repeat the processes. This is to get access to any layers of metal fouling that are trapped behind powder fouling. It is surprising how often you run through the Foul Out’s cycle until it indicates a clean barrel only to have it light up again (indicating fouling) after scrubbing the barrel and starting the Foul Out with fresh Cop Out liquid.

Remember, that .338 Winchester needed to cycle through the electronic cleaner 13 times before it came clean. Part of that was because there was so much fouling that the Cop Out liquid was exhausted long before the fouling was removed, but also because the metal fouling was layered with powder fouling.

The Foul Out cleaner does not always remove every minute speck of fouling, so once it indicates a clean barrel upon start up after the bore-scrubbing procedure, dry the barrel and follow with a good scrubbing with a copper remover on patches. If they come out without green or blue, great. If not, keep at it, alternating wet and dry patches with intervals of about 10 minutes of soaking time in between until there is absolutely no trace of color in a dry patch after it wipes a bore that has been soaking for at least 5 minutes in copper solvent. Finally, dry the bore with several clean patches and apply a rust protector such as Outers Metal Seal with a patch. Before shooting again, run a dry patch through the barrel to remove any residual rust preventative. Often, the first shot may be off from the expected point-of-impact, usually high, so a fouling shot is not a bad idea before hunting or shooting for score.

Take the stock off the gun and clean underneath. It’s surprising what collects between the metal and the stock. This can affect accuracy, particularly crud that contacts a floating barrel.

Trigger Cleaning
Clean the trigger by spraying the mechanism well with Crud Cutter. Do this chore outdoors because grease-cutting solvents can be nasty if you breathe too much of them. Work at the trigger from all angles and spray into every hole or access point you can find. Use lots of spray; the runoff is what takes the junk with it. Remember that after the solvent dries, the metal that remains is completely clean and will rust quickly if it is not protected. Spray the trigger with a good lubricant/protector such as Rem-Oil or Outers Tri-Lube. Make certain the lube is not temperature sensitive, there are few things in life more aggravating than a hunting rifle that fails to shoot because oil has gummed up in the cold.

Bolt Cleaning
You can give the bolt the same treatment by spraying into every available port with a good degreaser. However, the best way to clean a bolt is to disassemble it and then clean the parts with degreasing solvent. Check your owner’s manual for instructions on how to take the bolt apart on your particular rifle. Remember that the metal will need to be protected from rust and lubricated. Here again, make sure the product you choose is not temperature sensitive. One of the most common problems with cold weather hunting is when rifles fail to fire because goo in the bolt hardened in the cold.

Coat all metal surfaces with a good rust preventative before assembling the action back in the stock. These are areas that you don’t access with a normal rubdown, so be sure to use a long lasting protector such as Outer’s Metal Seal or Shooter’s Choice Rust Prevent.

Performance Shooter Recommends
If you properly clean the bore after shooting sessions, things will go a lot easier in the future. Because you are not allowing fouling to build up, each cleaning session should be relatively short. Also, by cleaning the barrel completely each time, you will allow the bullets to gradually smooth any minor imperfections in the bore, which in turn reduces fouling and enhances accuracy. Thus, the next time you miss, you will need another excuse, because it won’t be due to fouling. We usually blame the wind.


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