Countless things go into achieving rifle accuracy, and just as many things can make a rifle shoot poorly and erode accuracy. So where do you look when your trusty rifle isn’t grouping like it used to, or when that new barrel burner isn’t shooting up to its price tag?
Many factory rifles now guarantee sub-MOA (minute of angle) accuracy at 100 yards. So, if you bought a rifle in the past five years and it can’t group five shots under an inch at 100 yards with premium ammunition, you should keep reading.
Here is a five-part diagnostic checklist that can solve many common accuracy problems.
Check for Rock Solid Scope Mounts and No Play in Sights
The first thing you need to check when your rifle is shooting poorly is the sighting system. Most of the rifles that come into my gunsmith shop for accuracy issues have loose sights. If your groups are all over the place with no rhyme or reason to the pattern, this is likely the problem.
Check iron sights by trying to move them with your hand. If there is any movement at all, they need to be fixed. Fortunately, there are many ways to tighten the fit of a dovetail sight. A metal shim, lightly peening the dovetail, and a drop of solder can solve this problem.
If a rifle is fitted with a scope, there are many more things that can go wrong. To start, make sure all the screws on the scope rings and bases are tight. If you find a loose one, you may have found the issue already, but beware, it’s important not to overtighten these screws since many rings and bases are made out of aluminum and the fine threads are prone to stripping. There are recommended torque settings for the screws in your rings and bases set by the manufacturer. Look them up, and use a torque wrench to lock everything down like it should be, and shoot again.
Listen to What Your Brass is Saying
An empty brass casing can tell you all you need to know about your chamber. During the firing process, your brass makes a reverse imprint of the chamber, revealing any flaws that might be hard to see otherwise. Saving the brass from your day at the range can save you valuable time later and answer lots of questions if rifle accuracy problems arise.
First, look at the casing itself. Are there any bulges or odd discoloration near the mouth of the case? Next, look at the primer. The primer is your ignition system and can have significant effects on accuracy. I have seen rifles that were wildly inaccurate because of a broken firing pin that still managed to set off cartridge primers.
Whole chapters of books have been written about how primers look when things aren’t right. If you notice that your dimpled primers look different than they usually do, it may be time to take the rifle to a gunsmith.
Inspect the Crown
The crown is found at the muzzle of your barrel and is critical for rifle accuracy. It should be uniform and not have any burrs, dings, or dents.
Most crowns are designed to avoid damage to the critical areas, but they still can get beat up through years of use in the field. Taking your rifle to a gunsmith to recut a crown is a very common and inexpensive job that can solve some accuracy issues.
Ensure Rifling Twist Rate and Bullet Weight Are Compatible
Occasionally, the combination of certain rifling twist rates and bullet weights can kill a rifle’s accuracy. Diagnose this by looking at the impact of your bullets on paper at 50-100 yards. If your impacts look oblong or sometimes even sideways (keyholing), your bullet isn’t stabilizing properly and is tumbling on the way to the target. This is becoming a more common issue with modern calibers that use longer, heavier bullets with higher ballistic coefficients.
Your twist rate can be easily measured using a clothespin and cleaning rod and cross-checked with this chart to see if you are using the correct weight bullet. The fix for this problem is simple: try different bullet weights.
Look To the Stock: Imperfect Bedding Can Kill Rifle Accuracy
The bedding on your rifle is critical for accurate shooting. The bedding is basically a reverse imprint of your action in the stock. A well-bedded action will have a consistent position from shot to shot. There have been countless articles written about glass bedding an action, (editor’s note: this is the best one), but how do you identify bedding as your rifle accuracy issue?
Start by shooting a group at 100 yards. A recoil lug that isn’t bedded properly can cause erratic groups without any consistency. On a wooden stock, a crack running from the recoil lug to the magazine box is a telltale sign of this problem.
If there is a pattern to your grouping, that can be used to troubleshoot bedding issues. A pattern that prints in a vertical string can usually be corrected by relieving the bottom of the barrel channel in the stock. Any horizontal trending groups are generally caused by uneven pressures on the sides of the barrel channel.
Some firearms, such as pre-’64 Winchester Model 70s, have a screw in the forearm used to adjust the tension and harmonics of your barrel.
Bedding issues can be fixed at home, but it is better to take it to someone who has done it before and is comfortable doing it.
Know When to Take a Rifle to a Gunsmith
Unless you have access to a machinist buddy with a lathe, some of these fixes and adjustments must be made by a professional gunsmith. If you’re lucky, you already have a gunsmith that you know and trust to do work like this. If not, you can go here to get a walkthrough of the best ways to locate and get in touch with a gunsmith in your area.
One of the first things your gunsmith will likely ask after you present a rifle with accuracy problems is if you reload your own ammo. This is not the time to get defensive about your reloads. Explain exactly how you do it, and if it ends up being the problem, learn from it.
Keep your brass and give it to your gunsmith along with some of your unfired reloads. This will help them identify any ammunition-related accuracy problems for you.