I’ve seen the scenario over and over at the range where a shooter is having trouble with group consistency and discovers his action screws, or one action screw, is loose. He tightens them up and group consistency immediately returns.
The assumption is then sometimes made that “those action screws” can really control accuracy. From that point forward that shooter, and everyone else who witnessed the event thinks action screws can control rifle accuracy. To some extent they are right but action screws on a traditional bolt action rifle cannot be used to fine tune the weapons consistency as some believe.
Torque only affects accuracy if the action screws are loose enough to allow movement or shifting of the action in the stock. For maximum accuracy they should both be tight, 30 – 40 in lbs.
Their only job is to hold the action solidly in the stock. They were not designed for and cannot be used for any kind of tuning for accuracy.
What is stock creep?
Stock creep occurs when the fit between the action and the stock is so poor movement occurs during the shot, or when stress is applied to the stock that is not normal. An example of stress that is not normal would be when a bipod is installed and a firm grip on the stock causes flexing.
Some of the newer polymer stocks are so cheap this can occur on a rifle right out of the box. It is best to replace these with after market stocks that are more substantial although I have been successful using glass bedding compound to stiffen this things up.
By glass bedding the action, the recesses in the fore end, and making sure the barrel is completely free floated, I have seen marked improvement in accuracy using these cheapo stocks. Stock creep can happen on old wooden stocks or damaged stocks that prevent a tight fit between the action and the stock.
In these cases, it is always best to change stocks for one that is sound. This is not to say that stock creep can’t happen on a brand new stock that has not been fitted properly. If you have this situation, return it. If that is no longer an option, don’t fret. A good bedding job will correct this and make your rifle more capable than it ever was.
Can stock creep or bedding screws really effect rim fire performance?
It’s easy to see how a loose fitting action can effect accuracy in large bore center fire rifles with a ton of recoil. When shooting a 300 mag, even things that are tight and well designed are going to move at times. But why would a rimfire, with no recoil, really be effected by this?
Even though it is very slight, there is recoil produced when you shoot a rim fire. When shooting a rim fire pistol you get a better feel for what is really happening. Even the slightest recoil that can cause movement of a couple thousandths of an inch which translates to a big error at 100 and 200 yards.
With a loose fit, even transporting the rifle in you car or truck can make things change. If you are looking for your rifle to be a tack driver just go ahead a do the bedding job and free float the barrel. Even if this doesn’t solve the problem, you now have fewer variables to investigate.
I am certainly no scientist. I do not have the patience to use proper design of experiment protocol in order to organize and submit proof data to the scientific community in order to prove my hypothesis. I am an impatient rifle shooter who wants to know the facts as quickly as possible.
I have actually conducted some quick trials myself which consisted of changing action screw torque (yes I actually used a torque wrench) and compared group sizes. The results that I saw were completely inconclusive.
The only thing I learned was to minimize group size, action screws had to be as tight as possible without stripping the threads. This was true on two separate guns.
Here is another video posted on Youtube by the Long Range Shooters of Utah in share mode where the same tests are run for the same reason, to determine what effect actions screws had on accuracy. His results and mine both agree.
Inconclusive. It looks like we have found another of the many many variables involved in long range accuracy that is not the Holy Grail. I’ll keep looking. When you use common sense to think about it, if the action can move at all, groups are going to be larger.
The only thing that stops the action from moving is when the screws are tight and the action is bedded, settled, in a location where it can’t move. Check out this article on glass bedding a rimfire stock. Shooting is complicated enough.
Let’s not make it more so by trying to create something else to worry about when there is really nothing there. Here is an article on action bedding that really does have a postivie impact on rifle accuracy. Check it out !
Can action screws really be used to tune accuracy?
In this author’s opinion, no. As far as the action goes, only a loose action resulting in movement of the action between shots causes large groups. If there is some combination of tightness of action screws that yield improved accuracy,
I would have to say there is something else wrong with action fit that needs to be corrected. In this situation, make sure the action screws are as tight as you can get them. Tighten the action screws to 30 – 40 in lbs without stripping the threads (here is the torque wrench I use to ensure I don’t strip threads or leave them too loose) then investigate for looseness of the action and contact between the barrel and stock.