December 23, 2015
When a rifle suddenly goes “bad,” often it's a quick fix.
Your deer rifle sat in the closet for the last nine months. The season approaches, so you haul it out for a sight in session, and things don't go well. Three shot groups more resemble shotgun patterns, and no rounds wind up anywhere close to the point of aim.
Your rifle has just gone “wacky.” That's not uncommon. It happens more than many shooters think, but it is often a matter of one, or two, minor things that you can easily fix on your own. It's a matter of identifying and eliminating the possible problems. Here's how to get started.
Is it your ammunition? If you're shooting a load with proven past accuracy, that's not the problem. If you changed to a new load it could be. Some guns don't like some loads. Check the gun with a load you know works to eliminate that variable.
Check your scope mount system. Loose scope mount screws are one of the major culprits in a “wacky” rifle, and they can easily loosen. Tighten the screws holding the scope in the rings. With a mounting system that uses a separate base plate, remove the scope and check the base plate screws. They are often the problem. If your mount system has opposing adjustable windage screws on the rear mount and you're getting horizontal stringing, you can bet that's the problem. And, it's a common one. It's not a question of if they will loosen, merely a matter of when.
While you have the screwdriver out, apply it to the action mounting screws. If they have loosened, the action will be wobbling around in the stock and tossing bullets randomly. This is especially critical with pillar-bedded actions. Those two screws must be snugged tightly!
These steps will normally fix the problem. If they don't, your Gremlins lie in the barrel or in the stock bedding.
Most rifles have a sling swivel stud inserted into the forearm. Whether the stock is wood or synthetic that stud can, over time and recoil, work its way up enough to contact the barrel. If that happens it radically changes the barrel harmonics and groups will open up considerably. Remove the action from the stock and check the stud. If there is a mark on the barrel at the stud point, that's likely the problem and the stud screw needs to be shortened to not contact the barrel.
If your rifle uses a fully free-floated barrel, it is possible that the stock has warped and is contacting the barrel. This also puts unwanted pressure points that alter harmonics. This is not all that uncommon with wood stock in a humid climate like Florida. Check this by taking a crisp dollar bill, and starting at the tip of the forearm, slide it back between the barrel and stock to the chamber area. If it slides freely you are free-floated. If heavy resistance is felt along the way that could be unwanted pressure points.
You can identify those pressure points by removing the action from the stock, applying Durrie Sales' Prussian Blue to the underside of the barrel, and then carefully lowering the action back into the stock while keeping the barrel perfectly parallel with the stock until it is seated. Tighten the action bedding screws, let it sit for a few minutes, then remove the action. Any high points in the stock will be marked with the blue and can be sanded down. Put the blue only on the barrel and not the chamber area or the few inches of barrel ahead if it. That area is supposed to contact the stock.
That leaves the barrel. If you changed from copper jacketed bullets to moly-coated loads, your problem could lie there. Moly-coated bullets normally require the barrel be scrubbed clean of all copper fouling before they will shoot well. A good cleaning with a copper removing solvent will help.
If that doesn't work you might have a damaged crown or severe throat erosion. That requires the services of a good gunsmith, and possibly a new barrel.
Fortunately, most “wacky” rifles are more easily fixed. FS