The editor is in a scope swapping frenzy on the test range
Phill Price weighs up the pros and cons of swapping scopes
Over the last decade, the Weaver standard scope-mounting system has slowly been creeping into the airgun scene. As much as I understand why you might use it on a .50 cal, heavy machine gun, I don’t see why you’d want it on a recoilless airgun. The 11mm dovetail has served us perfectly for many decades and is subtle and discreet along the back of our beloved rifles. This is how I feel sporting guns should look. Weaver rails look far too military for my eyes.
No scope shift
Having a steel bar that runs at 90° across the rail ensures that no amount of recoil can shift the scope, but that’s of no relevance to airgunners using recoilless precision airguns. What it could potentially do is offer an ‘ index position’, so that as you change from one scope to another you could position it fore and aft against a fixed, hardpoint, for the sake of consistency.
The only sensible explanation I’ve been offered for its usage, apart from looking ‘ tactical’, whatever that means, is that you can have a number of sights zeroed for your
rifle and can swap them over instantly. Of course, each one needs to go back to the precise zero or it’s a worthless exercise. If you have to shoot a paper target to be sure, and make a small amount of adjustments, you might just as well stick with the ubiquitous 11mm standard with a hard stoppoint on the rail.
To understand if this return to zero claim was fact or fiction, I sourced an 11mm to Weaver adaptor rail made by B-Square and got two scopes that I know and trust, setting each up in Weaver rings. I chose to use my BSA R10 MkII because it’s stunningly accurate and its magazine sits low in the action, so that there’s no cut- out in its rail. Next, I zeroed each scope carefully at 35 yards, on a relatively calm day so that the wind wouldn’t be too much of a factor, allowing for the fact it always is to some degree.
Because the scope rings are tightened with thumb wheels, I believed that the torque of the fitting bolts wouldn’t vary too much and affect the results. I’d just do them up as tightly as I could with my fingers, which shouldn’t give too much variation.
My plan was to shoot a group with scope A, remove it, and fit scope B, then shoot another group. I’d repeat this until I had enough groups to form an opinion of the repeatability of the zero. Would scope A go back to zero every time? Would scopes A and B be dead on, or miles off? What was needed was trigger time and a good deal of patience.
As the pictures show all too clearly, the scopes did go back close to zero every time. I find this kind of test really tricky to trust completely because we never shoot perfectly, and outdoor conditions are always a factor even in relatively light winds. I’d get all stressed when a shot went wide and then excited when I got a clover leaf group on the bull. The reality is that there are lots of variables beyond the mounting system in question.
The practical realities were that I found swapping scopes some 60 times no big deal, although it was clear that one set of mounts fitted the rail differently to the other and took many more turns of the thumbwheels to tighten fully. If I were to run this test again, I’d swap the thumbwheels for nuts and tighten them with a low-range torque wrench to eliminate that variable.
The bottom line is this. No shot landed more than ½” away from the bull during the removal and refitting of the two scopes. Is a 1” group good enough for you at 35 yards? Some will say yes, others will say no. The mounts were top- class units from Sportsmatch and the base from B-Square, both prestigious companies, so no corners were cut to save money.
Can I now say that two scopes in Weaver mounts can be removed and fitted with NO change of zero? That’s too hard to say, but I did prove that they come pretty close and for those who swap from day to night vision, they’re an honest option. However, being an accuracy nut, I like to settle a gun down by breaking it in slowly, getting the optimum zero, then locking the whole thing down and leaving it alone. I like to know that my rifles are dead on as they leave the gun cabinet, and anything I can do to assure that is what I’m going to do. I’ll be staying locked to 11mm rails for the foreseeable future, but then you knew that about me anyway.
Trigger- time is the only way to answer some questions Would the scope go back to the exact same place every time? I did the bolts up finger tight for this test No amount of removal and refitting seemed to affect the zero significantly