Are you underestimating the importance of your scope mount?
10:24 31 January 2017
If you think mounts are nothing more than a simple lump of metal and you can get away with a cheap one, then you are misunderstanding these vital parts of our sport
“Simple black lumps of metal that hold your scope, that’s all they are.” So said a fellow airgunner to me and, to be honest, I was a little shocked. ‘Simple’ is one thing well-made mounts are not. To do their important job properly, they must be made precisely and match perfectly the scope and rifle they’re intended to marry.
Sure, there are lots of lumps of black metal out there going cheap, which will plop your scope somewhere near the top your rifle, but is that what you want for your dream gun? I can’t understand people buying a £600 rifle, a £150 scope and then using £9.99 mounts. The old saying about a chain being as strong as the weakest link applies here.
So what do we want from a set of mounts? Firstly, they need to match the scope’s body tube, being either 1” or 30mm (in the firearm world, 34 and 36mm bodies are coming along).
Then we need to choose between single-bolt or double-bolt designs. For me, the choice is easy – double-bolt models don’t cost much more or weigh enough extra to be of concern and I like the extra support. Field rifles can take knocks and bangs as part of daily life, and having the reassurance that the double offers makes me more confident in the rifle’s zero.
One of the most important factors when choosing a mount is the type of rifle you shoot. Recoiling guns benefit from the huge, gripping force provided by one-piece mounts, so they are the ones I recommend.
When you slip the trigger on a springer, a steel piston weighing close to a pound hurtles down the cylinder at around 200mph and comes to a halt in fractions of a second. The rifle recoils backwards first and then, in a vicious snap, reverses direction and tries to slide the scope backwards down the rails.
It’s a brutal environment for a delicate optic and a huge challenge for the mounts. The better one-piece mounts have a recoil pin or stud that positively engages a drilling on the top of the cylinder to lock the two together mechanically.
I believe it’s wise to use soft Loctite on all the bolts of a springer, including the ones on the mounts, to prevent the complicated recoil cycle working them loose.
On pre-charged pneumatics and other recoilless guns, the concern is about correct alignment and solid support. Your scope must sit perfectly above the centreline of your barrel. If it’s placed to one side or the other then you suffer a problem known as crossover, which causes the pellet to land to one side or the other of your intended aiming point. Selecting a mount designed for the brand and model of rifle will eliminate this fault. For example, some, but not all BSA rifles have rails that are different for the industry standard 11mm, but you can get specific mounts to compensate.
Many PCPs have a magazine that protrudes upwards from a slot in the scope rails, and this must be allowed for in height. This often means choosing medium or high mounts regardless of how high the scope would need to be otherwise. The central part of the scope, the saddle, often coincides with the position of the magazine, making the problem worse. Please take the time to check these dimensions on your gun before you buy, or you may be frustrated.
Precision isn’t only important where the mounts contact the scope rails. It’s equally important where the two halves of the rings meet. Any misalignment here can mark or even crease the scope’s body tube, making it worthless if you ever try to sell it. The better made ones have a subtle radius on the edges to eliminate any marking issues and give a professional finish to the set-up.
I make no apology for my support of the British mount manufacturer, Sportsmatch. I’ve used their products for over 30 years without a single complaint and they have always had the right mount for any project gun I’ve built. Their catalogue is huge and ever-growing, so you’re likely to find what you need, and their mounts are so strong that they supply the elite military teams around the planet. You can’t get a better endorsement than that.
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