DIY: When a Good Gun Goes Bad

When you are the gun guy in the neighborhood it’s amazing how many "friends" you have. My shop is the first stop when somebody is having gun troubles. All too often it’s an accurate rifle that has suddenly started misbehaving and spraying the target with patterns instead of groups.

I have little tolerance for times when a good rifle goes bad. There is one course of action: Find the problem and fix it. Don’t let a bad rifle off the hook. Make it take responsibility and behave again. I’ve developed a checklist of steps, which you can use in your own shop, to help.

Clean the Bore—Correctly

I can’t tell you how many times a fouled bore has been the source of accuracy problems. I also can’t tell you how many times the owner has denied it. Almost without fail, the owner insists they "already cleaned it and it still won’t shoot!"

The key here is to clean the bore correctly, which is something few gun owners have the knowledge or temperament to do.

Running a few patches with some solvent through the barrel is not enough. The key is to clean the bore down to bare steel, and remove all powder and metal fouling.

Start with a bore solvent that will remove both powder fouling and copper fouling, such as Hoppe’s No. 9 Bench Rest. Glove up, and use eye protection and lots of ventilation. Clean from the rear when possible, and use a rod guide to keep the rod centered and to keep crud out of the action.

Make several passes with a new wet patch each time. Pause a few minutes between patches to allow the solvent to work.

Leaving the barrel wet with solvent, use a properly fitted bronze brush soaked with solvent to make several passes. Keep the brush wet with solvent, reapplying after every couple of passes. Don’t dip the brush in the solvent bottle, as this will contaminate the remaining solvent. Instead put some solvent in a small container, and dip in that.

Never reverse the brush in the bore; push it all the way out of the muzzle then pull it back. After use, clean the solvent from the brush with a spray of degreasing solvent, allowing it to run off the brush and flush away the gunk. This prevents abrasive debris from accumulating and extends the life of the brush.

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Let the gun sit for a few minutes, and then follow with a couple more wet patches. Wait a few more minutes, and then run dry patches through to remove all traces of the solvent. Follow with a few patches soaked in a degreaser like acetone and a final dry patch. Some bore solvents do not mix well, and we are about to get a lot more aggressive.

Switch to an aggressive copper-removing solvent like Sweet’s 7.62, Montana X-Treme Copper Killer or Barnes CR-10. Run a couple of wet patches through the bore, and let it sit for a few minutes. Follow with another wet patch, wait and repeat. Use snug-fitting patches so they get into the corners of the rifling. I often use the next smaller size jag and double up the patches so there is thicker cotton that will shape to the lands and grooves better.

The goal is to let the solvent sit for at least five minutes and have no blue stains on the next patch through, indicating there is no remaining metal fouling. Remember, though, a brass jag can leave a “false” stain on the patch. It’s usually on the inside of the patch. When in doubt use a plastic or stainless steel jag.

If it’s just not happening fast enough, use a brush. Many sources recommend nylon brushes, but I don’t think they are aggressive enough. I use a bronze brush with the understanding that strong solvents will eat the brush. Bronze brushes are only good for a few cleaning sessions, so treat them as a consumable product.

After scrubbing there will be a lot of blue gunk on the next patch through the bore. Some of that is from the dissolving brush, some of it is from the fouling. It can be a lot, so don’t be shocked.

Most aggressive copper solvents should not be left in the bore for more than 15 minutes. That doesn’t mean you’re done after 15 minutes, only that you need to remove the old solvent and replace it with fresh. Keep working with wet patches and brushes to refresh the solvent often.

Even when patches come out clean, it’s possible to have copper fouling trapped between layers of powder or carbon fouling. Clean all the solvent out of the gun and switch solvents with the idea that one might get the fouling that the other does not. Return to a general-use solvent like Hoppe's No. 9 Bench Rest.

If the bore is really fouled, Kroil and J-B Bore Cleaning Compound can help loosen things up. Kroil has excellent penetration qualities so it will work under the fouling. The J-B Bore Cleaning Compound is slightly abrasive so it cleans the crud and copper out, but it’s not abrasive enough to damage the bore.

Wet a few patches and saturate the bore with Kroil, and let it soak for a while. Wet a tight-fitting patch with Kroil, and then coat it with J-B Compound. Run it through the bore at least 20 passes; twice that is better. Check the patch often, and add more J-B and Kroil as needed. If the patch gets worn, replace it.

Switch to a clean patch wet with Kroil, and clean all the goop out of the bore. Then use a few dry patches. Follow with a couple of wet patches using an aggressive copper solvent. Let it stand five minutes then run a clean patch. If it comes out with no blue stains, you are almost done. If there are blue stains, keep repeating this process. Use both solvents and the J-B and Kroil in rotation until there is no sign of blue on any patches after letting the aggressive solvent work for five minutes.

Until you can soak the bore with an aggressive copper-removing solvent, wait a timed five minutes, and then run a clean patch through without blue staining, the gun is not clean.

Once it’s clean, you must remove all traces of any cleaning agent. Use patches soaked with acetone until the bore is clean, then follow with dry patches. Wet a few patches with a CLP oil like Clenzoil, and swab the bore. Follow with a clean patch to remove excess, but leave a film.

Give the chamber the same treatment with a couple of swabs. One wet with oil, the other to dry. Clean up any solvent that has dripped into the action or other gun parts. Then oil to prevent rust. Very often a thorough and proper cleaning will correct any accuracy problems. If it doesn’t, cleaning checks one big issue off the list.

Test the Scope

Make sure all the ring screws are tight, and that the base screws are holding the base tight to the receiver and not bottoming out. Shake the scope to see if it rattles. If it does, something inside is broken. This is more common than you might think.

Look through the optic to see if the field of view is clear edge to edge. Check the parallax to make sure it's correct. Fix the gun in something to hold it with the crosshairs on a 100-yard target. If the parallax is adjustable, set it for 100 yards. Look through the scope without touching the rifle, and move your eye back and forth and up and down. The crosshair should remain fixed on one small area of the target. A little movement is usually to be expected, but if the crosshair moves more than an inch or so on the target, parallax problems may be the source of the accuracy issues.

Use a boresighter—the kind with a grid, not a projected laser—to check windage and elevation adjustments. Fix it on the gun, and run the scope adjustments up/down and left/right to verify they are tracking correctly.

With any doubt, install another scope. Most of us have a scope lying around that we can use temporarily to eliminate the original scope as the potential problem.

Examine the Stock and Bedding

It's unusual for the bedding to be the problem, unless somebody has been messing with it. However, it's not uncommon for the action screws to be loose or the stock to be cracked.

Pull the stock off the gun, and check for cracks or splits. Check the bedding for flaws. I recently examined a rifle where the bedding material had flowed into the bedding pillars. That meant that the action screws were taking some of the recoil stress. Also, the recoil lug was in full contact with the bedding. It’s best if the recoil lug only makes contact on the rear, load-bearing surface.

Reinstall the stock, properly tightening the action screws, and check the bedding by holding your fingers on the line where the action and the stock meet. Alternately loosen and tighten each of the action screws. If you feel any movement of the action in the stock, the bedding is incorrect and is putting stress on the action. With your fingers on the junction you can feel movement that often you cannot see. If the bedding is the problem it can usually be repaired by glass-bedding the action into the stock. (There are detailed instructions in my first gunsmithing book, Gunsmithing Made Easy.)

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Check to see that the barrel is floated. A dollar bill is still the best way to check this. Wrap the dollar around the barrel and pull the ends up. If it can pass between the barrel and the stock for the full length without binding, the barrel is floated with enough clearance.

With wood stocks, barrel contact is often the source of problems when the wood warps. Any wood stock that has been subjected to a lot of moisture can cause issues. Remember, humidity is moisture. If a stock absorbs a lot of water and the wood swells, it can trash accuracy.

Be aware that some stocks are designed to have contact with the barrel. For example, many Remington Model 700 rifles use a pad at the tip of the stock to put pressure on the barrel. If the stock has warped this can really mess with the accuracy. If you suspect that has happened, remove the pad and float the barrel.

Check the Crown

A bad barrel crown is probably the No. 2 reason guns go bad, right behind a fouled bore. Check to be sure the crown—particularly the front edges of the lands and grooves—isn’t dinged or gouged. Rough spots in the crown can hurt accuracy by destabilizing the bullet as it exits the bore.

With the proper tools you can re-crown a barrel, but it takes experience to do it correctly. Re-crowning is best left to a knowledgeable gunsmith.

The cumulative effect of checking and correcting all of these things should bring a rifle back to shooting as well as, or even better than, before. If it’s still not shooting well, use a bore scope to make sure the barrel is not shot out. In that case, the barrel will need to be replaced. If that still doesn’t solve the problem, either trade the rifle or contact a priest for an exorcism.

Editor’s Note: This article is adapted from Bryce M. Towsley’s latest book, Gunsmithing Modern Firearms. Autographed copies are available at brycetowsley.com.