Magnetic light mounts on your barrel: accurate or not?

Rifle accuracy

If you attach a hunting light to your rifle’s barrel using a magnetic mount, will it affect accuracy? 

That’s a simple question and in one way the answer is equally simple to figure out.

On the other hand, there’s a depth to the question — and its answer — that’s worth a full thesis to explain.

But we’re not here for the thesis! This video by Eagleye Hunting Gear, which I was commissioned to do, gives you the short answer along with a few clues about barrel harmonics. 

Watch the video to see what sort of influence barrel pressure can have on accuracy, and read on below to improve your understanding of it all. 

Just as heat affects the way a barrel performs, so does any pressure applied to it. 

When you fire a shot, the barrel will vibrate (or whip or whatever term you wish to use) as the projectile travels up the bore. 

As a result, the muzzle will move, pointing in different directions as the barrel whips around. It’s a tiny movement but enough to shift your point of impact. 

You want the effect of the whip to be the same for every shot you take, so the muzzle is pointing the same way every time a bullet leaves it. That’s what makes a tight grouping. 

Attach a magnetic mount to the barrel and it will make the barrel vibrate differently, like a guitar string being held down by a finger to change the note. 

And as the two rifles used in the video demonstrate, you’ll get a different point of impact from the effect. 

True, shooting a couple of groups from just a couple of rifles is no conclusive test, but it serves to illustrate the point. 

The effect will be different from rifle to rifle, so the lesson is to fire a few groups with and without your light mounted to your rifle and see what happens. Either adjust your sights to suit or, if the results are way too inaccurate to tolerate, mount your light to the scope or the stock. 

Don’t go out and hunt without first working it out. You’ll have no idea where your shots are going. 

You could be lucky and find no change. After all, barrel pressure is applied by barrel bands on, say, lever-action rifles. And the SMLE rifles referred to in the video are an example of a rifle will contact points and uneven weights applied from one end of the barrel to the other, yet they can shoot pretty accurately. 

However, it’s no accident that manufacturers go out of their way to free-float the barrels in most of their rifle models. It is far easier to be consistent and accurate with a barrel that’s free of any contact.  


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