Achieving Practical Accuracy

by Bob Londrigan, published in Front Sight Magazine, January 2004

If you followed the advice presented in my last few articles, there’s a good chance you now have your gun running quite well.   That being the case, we are now going to look at an issue that can affect your scores as much as a reliable gun – accuracy.  We are going to look at “practical” or “applied” accuracy.  This is the ability to hit an exact spot on the target under match conditions.  It encompasses the actual mechanical accuracy of your gun, plus features that aid the shooter in achieving accuracy. 

 Before you start making changes, test fire your gun to see what type of groups it shoots.  I prefer to sight my gun in offhand because it more closely resembles what I will be doing in a match.  You may, however, choose to shoot from a rest for a more accurate assessment.  If you are not getting consistent groups, check the vertical stringing.  If your groups are a lot larger top to bottom than left to right there is a good chance that your barrel is not locking up consistently. Check for binding at the back of the hood or the sides.  If your groups are inconsistent, first make sure the problem is not your shooting technique.  If your technique is solid, you could be getting hits on the compensator or jackets may be peeling off the bullets.

Let’s begin by looking at mechanical accuracy issues in more detail.  For the game we play, a gun that shoots three to four inches at 25 yards is probably sufficient.  But since it’s always better to hit exactly where you are aiming, a gun that shoots under an inch will get you better scores.  For your gun to perform at this level of accuracy it must do the same thing every time it cycles.  The following factors affect how your gun cycles, and as an added side effect they will also improve reliability:

• Barrel fit – The barrel must lock up to the same place each time.  The hood should fit the slide flush in the back and there should be no vertical play when the barrel locks up.  The sides of the hood are not as critical but there should not be a sloppy fit.  Make sure that there is no side to side bind when going into lockup.  There also should be no play at the front of the barrel where it locks up with the slide or bushing when the gun is in lockup.  If you have a bushing there should be no play between the bushing and the slide.  Also check your barrel for springing: insert your barrel in the slide and push it up into lockup.  It should feel solid, not mushy or springy.
• Barrel quality – There are several after-market suppliers who make excellent barrels.  If you feel your factory barrel is not up to par or you are replacing your barrel, choose a quality barrel and have it properly fit.
• Slide-to-frame fit – Although this is over emphasized at times, it is good to have the slide fit the frame to within 0.001.  However, I have seen many loose guns shoot good groups if the barrel fit is tight.  The slide-to-frame fit is more important on an open gun where the scope is attached to the frame.  On a limited gun, the fact that the sights are attached to the slide negate most of the effect of a sloppy slide-to-frame fit.
• Ammunition – Test fire your ammunition and play with your loads to make sure you have a load that is accurate in your gun.  Test by shooting groups from a rest. Make sure you reloading techniques produce consistent ammunition.  You should have a tight consistent crimp on the bullet, and your overall length should not vary from cartridge to cartridge.
• Chamber headspace and cut - Your chamber should be cut long enough to accommodate the longest piece of brass that you might encounter, but not so long that you create excessive headspace.. The throat of the barrel should be cut long if you are going to load longer than factory loads (over 1.135 inch in 40 S&W.)
• Barrel crown and compensator clearance - Make sure your barrel is crowned properly and that there are no nicks in the crown.  If your gun has a compensator, inspect it for signs of bullet impact on the baffles (i.e., copper colored smears on the bore of the baffle.) If you see this align ream the compensator for clearance.  Because jacket material can build up in the comp and cause hits on the comp, you should perform this inspection on a regular basis. Lately I have been reaming at 0.385 to combat this buildup.
• Sights/Scope - Inspect your sights/scope checking for loose parts/screws, or misalignment and correct as necessary.

When your gun achieves mechanical accuracy, then you can start working your way up to where you are shooting to your gun’s potential.  Shooter aid issues include anything that you can do to your gun that will speed up shooting accurately.  Realize that shooter aid issues affect the deliverable accuracy of your gun as much or more than mechanical accuracy.  Therefore, it’s important to tune your gun with the following shooter aid issues in mind as well:  

• Trigger pull – The trigger does not have to be screamingly light but usually lighter is better.  The trigger should be crisp and break consistently at the same poundage. Use a scale to measure this. Adjust your pre-travel to what feels best to you. I like about 0.040 inch but some people like more or less.  You will need at least 0.025 inch for safe function of the half cock notch. Adjust the overtravel stop for minimum overtravel. For some people, a little additional overtravel will minimize trigger jerk.  Use what works best for you.
• Sights – A good set of sights will make all the difference in the world for accuracy.  If you don’t have a clear reference point on the gun, you won’t be able to hit what you are aiming at. Experiment with different sights to find out what works best for you.  Thin front sights, sights with a wider notch in the back, fiber optic sights, fixed rear sight, and different size dots are just some of the available options.
• Fit of gun to hand – How the gun fits in you hand is often overlooked, although it is an important factor for accuracy.  The gun should fit your hand especially through the web area (area between your thumb and forefinger).  This will spread out recoil and make the gun point more naturally. Experiment with arched mainspring housings and different magwells to get a better fit.
• Balance of gun – The gun should be balanced so that it points naturally for you. If it does not, try adjusting the balance by adding weight to the front or rear of the gun.  Experiment with a heavier guide rod, magwell, etc.
• Ammunition – Work up a load is best suited for your shooting style.  You may shoot better with a slow, soft load or maybe you are better suited to a quicker, snappy load.  Practice with enough different loads so that you know what works best for you.

Once you and your gun have achieved a high level of accuracy, you’ll begin seeing your scores go up.  But to maintain this performance level, you’ll need to continually monitor your accuracy.   Sight-in your gun at each range session.  If your zero starts to move from one session to another, make sure you find out why before it causes you problems.  If something is cracked or worn out it will sometimes show up first as a decrease in accuracy.  As I’ve stressed before, you want to locate any problems in practice and not at the match.