A while back a gentleman brought me a factory gun that was shooting poorly; groups were averaging 2.5″ for five shots. It made no difference what ammo was used. The client had tried factory ammo and reloads in different bullet weights. He tried changing loads and seating depth, even neck sizing was attempted just to see if cases fire-formed to the chamber were more accurate.
All to no avail… groups ranged from a little over 3” at worst to about 2” at best, but there was no telling when it would throw the good, bad, or the ugly group.
There are many things that can be done to improve accuracy on a factory rifle, and some of them are well suited to the hobbyist who wants to improve the accuracy of a favorite rifle. By making these changes one at a time it will be clear whether the change you made improves the accuracy or hinders it. If you change multiple items at the same time there is no way to be sure what made the difference, although some gunsmiths prefer to do all they can at once to save some time.
Let’s start with the things you might do at home:
Check the bedding. These days there are many methods of bedding that are popular and work. Some rifles are bedded in an aluminum bedding block which is molded right into the stock itself. This is a great system and provides for better stability than many other approaches. Aluminum is unaffected by humidity, and temperature has almost no effect either.
With such a bedding block you will remove the stock from the action and take careful note of how the action, barrel, and stock are contacting one another. It is pretty easy to see what the designer had in mind for actual contact points.
The insert works like a ‘V’ block, so just scrape away any contact points that would interfere with the ‘V’ block arrangement.
If you have a wood or synthetic stock without a bedding block that is a “drop in” fit, then bedding might be a good way to improve the stability of the stock. This article is not intended to teach you how to bed a rifle. But here are a few important points to remember when bedding:
- always use release agent on the metal parts or you will have a nightmare taking the stock off the action later.
- The action need only contact the stock for a solid shooting platform, normally this means the rear tang, front receiver ring behind the recoil lug, and on the rear surface only of the recoil lug.
- It’s best to clear all other areas to avoid binding the action unnecessarily.
- Use tape or modeling clay to block off any areas of the action into which you do not want the bedding compound to seep.
Reloading can have a huge influence on the accuracy of a rifle. The biggest mistake that reloaders make is selecting a load and assuming it will shoot well in their rifle. You probably already know that not all factory ammo shoots the same in your gun, why would reloads be any different?
When I want an accuracy load for a new rifle I start by looking through my collection of reloading manuals. The Lyman and Nosler manuals indicate the loads they had the best accuracy from during their tests, so starting with that powder might give you a jump on the process. No two rifles are alike, so some will prefer lighter loads and others will work better with hotter loads. Experimenting at the range with your rifle is the only way to know for sure.
Start the loading process with your bullet seated .050” off the lands. Try several powders you think might work, all with the bullet seated to the same depth. Once you find the powder your rifle likes best then play with the powder charge for accuracy, changing the charge by ½ grain at a time, be sure to watch for pressure and stay safe.
Finally, when you have the best powder charge for your gun, try varying the seating depth to fine-tune the load. Normally moving in or out .005” in seating depth will change group size. If your chosen bullet won’t group with any of the selected powders then that bullet may not like your barrel, so try another bullet. The surface area of the bullet in contact with the bore can have a great deal of influence on ballistics, look for bullets with a different configuration if your first choice does not work.
If, at this point, accuracy has not improved, there is one more thing you can do before the rifle has to go to a gunsmith to be improved.
Check to see if the locking lugs on the bolt are engaging equally with a good percentage of their contact area. Machinist’s blue is a good tool for checking this. If you don’t have any, a permanent marker will do the same thing. Paint the backside of the locking lugs on the bolt, and let them dry. Now, put the bolt in the action and work it in the open and closed position several times. Then take it out of the action and look at the back of the lug, ideally the material you painted on the lugs will be scratched off where the lugs contact the action.
Even contact on the lugs with about 80% or more touching is what you are looking for. If one side touches more than the other it will cause accuracy problems, likewise too little contact area allows the bolt to move when the gun is fired, also causing accuracy problems. If you decide you need to lap the lugs be sure you get all the lapping compound back out of the action when you’re done. Remember, lapping the lugs can, and usually does, increase the headspace of your rifle. Tried all that and still no improvement?
Most shooters will have a gunsmith handle the following steps . . .
The next thing to try is a trigger job or a replacement trigger that is adjustable. A trigger job will often improve accuracy simply because it gives the shooter better control over the moment of ignition. If you don’t understand the workings of your trigger it is best to take it to a competent gunsmith. Keep in mind that changing the trigger might void your factory warranty so check that out first.
A hunting rifle will deliver excellent accuracy with a pull weight of three to four pounds if the pull is crisp enough to allow you to count on it to go off the same way every time. Ultra light target triggers are for the bench. For your safety and the safety of your hunting partners, keep the pull weight reasonable. A simple test is to drop the cocked, unloaded rifle on its butt from six to eight inches off the floor. If the trigger holds reliably it is safe to hunt with. Don’t drop a steel butt plate or hard plastic butt plate on the floor if you like your stock.
Take a close look at the crown on your barrel. It should be concentric to the bore. Problems that are common on crowns are wear from improper cleaning and burrs from machining or damage. It is surprising how often simply re-crowning a barrel will improve accuracy. Visible damage should of course be cut away, if necessary shorten the barrel a little before crowning. Keep in mind the crown can look OK and still cause problems, a bore scope is really helpful here. There are several tools available from Brownells and others that make it possible to re-crown a barrel in the home shop, without a lathe.
When we got to this point with the client’s rifle mentioned at the beginning of this article, we determined that rechambering would be the best way to determine if the barrel could shoot better or not. As a rule we perform an action tune. For hunting grade rifles this entails removing the barrel, facing the receiver, lapping the lugs as mentioned above, and measuring to be sure the bolt face is square. If necessary, we true the bolt face. We call this an action tune, some shops might call it “blueprinting.” In many rifles this process will solve the accuracy problems.
One drawback to this process is that it does increase the headspace of the action so we will have to perform a set-back and rechamber to correct it. The advantage of the set-back is that we are able to square up the breech face and barrel shoulder so that they match the action. In most cases we are only talking about moving the barrel back about 1/16th of an inch, so don’t worry about it being noticeable. Done correctly, it will not be obvious that a change has been made.
Rechambering allows us to make sure the chamber is properly aligned with the bore axis so the bullet is not introduced into the bore at an angle to the bore axis. We often find that the factory chamber was oversized and out of alignment with the bore. Because we set the barrel back, most, if not all, of the original chamber is cut away. Everything mentioned to this point in the article was done to the client’s rifle. Group size was reduced from an average of 2.5” to 1.5” but this was still not appropriate accuracy for a varmint rifle.
One other option would be to simply rechamber the barrel for a larger cartridge, such as an Ackley Improved. The client in this case decided it was time to install a new barrel to overcome the accuracy issues. We ordered a new stainless barrel blank from McGowen Precision barrels in .22 caliber with a 1-14 twist. The new chambering would be .222 Remington.
Most of the work we have accomplished to this point was on the action and stock, so it will remain with the gun. The new barrel was installed and we headed for the range with some ammo for sighting in. The second group showed some promise with three shots touching and the total group of 5 shots coming in at just under one inch. We then loaded up a few rounds with the formed brass neck sized with a Hornady .22 caliber Neck Size die.
Bullets seated to various depths were loaded, and at the range four out of the six groups fired were .750” or less. The best group turned out to be with bullets .015” off the lands, four shots measured .407” with a flyer making the total .725” Once broken in this barrel will easily shoot under ½” MOA.
Our client’s gun was a Remington 700 with the new style striker assembly that has a “Child Lock” built into the gas shield. The problem is these assemblies seem to have a lighter strike than the old style assemblies. So, the final change that will be made to this rifle is the replacement of this assembly with an aftermarket product with a much stronger firing pin spring. This enhances uniform ignition of the primer.
We broke this process up so that if you have a similar problem child you can go through the process one step at a time. A gunsmith should probably quote a price for several of the jobs as a group, like bedding, trigger job, and recrown. This would be a totally legitimate approach. If this work is done and accuracy does not noticeably improve, then the odds are that you have a bad barrel.
For comparison, we had a .338 Winchester come in during this same time period that was producing poor groups as well. Bedding, a trigger job, and a recrown were all that were necessary to “make it shoot.”
Fred Zeglin is a Custom Rifle builder with more than twenty-five years experience and an AGI instructor. Tools for the work mentioned in this article can be rented from www.4-dproducts.com