What scope should be mounted on a Big Bore? Or, is a scope out of place on a Big Bore? Those two questions, and hopefully some answers, will form the basis of our presentation for this week.
First off, let’s clear the deck of some misconceptions and non-starters: this is NOT about “what scope” as in what brand name or particular model, though that may come up as an example or illustration. Also, the issue of cost isn’t the main agenda either… only as an incidental fact of life.
One more time: Big Bores don’t start with an exact bore size, though consensus tends to set the boundary at .400 and up to what some would describe as ultra Big Bores. That would include less that a half-a-handful of ridiculous numbers to .700-cal. In my view, they are indeed ludicrous! They serve no practical purpose other than as a statement of hubris!
Then, some would want their .375-cal or 9.3mm recognized as being legal for DG, therefore that should be the standard of where to begin. Be that as it may, I’ll concede the .375 H&H as a Medium Big Bore, and any others of its ilk… but that’s it! So, we’ll start with the .375s and terminate with the .577. If it’s not in BARNES or HORNADY’s manuals… well, you’re not gonna find it mentioned here!
The reason for a RIFLE SCOPE is fairly obvious to everyone, I would imagine. So we don’t need to spend an inordinate amount of time on it. The scope’s primary function is to enable the shooter–in this case the hunter of large/dangerous game–to see things more clearly through magnification and illumination–to make the picture brighter and bigger. It does this through a series of lenses that magnify, give true colors, present a “flat field”, and collect more light in the process than the human eye is capable of. In general, the larger the front lens (objective lens) the brighter the “image” and the better it’s resolution. Of course, the amount of magnification is important as it makes possible the full resolution of the image while enhancing its brightness. These are general concepts well known by most users of rifle scopes. There are other matters, such as enhanced coatings on the lenses for the transmission of light rays. Again, in general, the fewer the lenses to absorb and/or reflect the light, the brighter and clearer the image will be IF the scope is properly constructed. The lenses are mounted in a steel or aircraft aluminum tube for rigidity and focusing. The eye lens (the part you look through) is a somewhat complex system of lenses designed to give that “flat field” of view, plus the color correction needed to eliminate the false color fringes to the image(s)–the “rainbow” effect seen in cheap scopes, etc.
The second purpose of a rifle scope is as an aiming device–it takes the place of iron sights mounted on the barrel. However, on MOST Big Bores, irons are still in place for two reasons: some folk prefer them over glass; and secondly, if the glass scope fails for any reason, there is a ready backup in the irons IF properly sighted prior to the hunt.
By that I mean: How BIG; how STRONG; what MAGNIFICATION range; external COLOR of the tube (the tube is painted matte black internally to control light from “bouncing around” within the scope); and MOUNTING system?
Usually… ahem, again “USUALLY” scopes for Big Bores are kept to a minimum size so as not to upset the balance of a finely tuned rifle. AND, to keep additional weight to a minimum as the rifle will already weigh in the range of 9.5 to 10.5 lbs ready to hunt. Then, a large observatory-size scope isn’t really needed in situations where the size of the beasts may have great difficulty fitting into your garage! We surely don’t need a 6 – 18X by 50mm to see and shoot a Cape buff at 50 yards! Do we? And, depending on the situation, that particular game in question will NOT be hunted on the edge of darkness. It doesn’t make a lot of sense to hunt DG when the lights may be turned off in 5 minutes!
That’s “USUALLY”… but there are exceptions, and when and where the hunt is less than “normal”, we must be prepared for the abnormal in removing the scope… or possibly changing it for another that is already sighted and in QD rings. Let’s say, for example, that that very lightweight 2.5x by 20mm is on your .416 Rigby for elephant. But you also have lion on your license. As your team sets out in search of an elephant, a majestic lion at 250 yards is spotted by one of your guides. He is in the open and so are you. If you continue in his direction, he will surely head for cover. IF you have the option of a second sighted rifle for King Leo, all to your good… if not? That’s where a second sighted scope could save your day! “Yes but”, you say, “It’s only a .416 Rigby!” “Those 400s are only making 2400 fps!” “Besides they’re too tough for lion!” True enough… but didn’t you ever hear of 350gr SPs leaving the muzzle of your cherished Rigby at 2600 to 2700 fps? Yes, it’ll take three minutes to change ammo and scope, and you can have your lion and eat your cake too! QD rings (Quick detach rings) firmly clamped into the ready-made grooves of your rifle’s receiver will allow for a relatively fast change of scopes. For a Big Bore rifle, with its awesome recoil, I prefer the mounts for the rings be machined into the receiver as an integral part.
I have a 2 – 7 X 35mm Burris on my 1895 Marlin Classic. That power range is ideal for my purposes, and the 35mm gives plenty of light on the edge of darkness. In dividing the objective lens diameter by the magnification being used, we have the diameter of the beam of light that enters the eye. During daylight hours, the human eye (the pupil) will normally dilate to 3-4mm. A beam of light larger than that is inefficient as some of it is “lost” in it’s inability to enter the eye. Nonetheless, at close ranges a wider field of view is preferable, especially when hunting DG. On the very edge of darkness, when black bear hunters anticipate connecting on a trophy, a larger front lens is preferred as higher magnification may be used, and the human eye will dilate from 5 to 7mm.
I think it’s also fairly clear than any scope for a Big Bore needs to be plenty strong. That is, it needs to handle the pounding it will take when the trigger is squeezed. Every time. That’s one sound reason why I use, and recommend, a fixed power, lightweight scope as there are fewer parts to shake loose, and less inertia. On both of my real heavy-hitters, the CZ550 in .458 Winchester, that has the ballistics of a .458 Lott, and the Ruger No.1 in .45-70 IMP,with the ballistic potential of a .458 Win Mag, I have fixed 4x by 20mm Burris scopes. They’ve proven to be tough and have eye reliefs of 5″. There’s little danger of getting “magnum eyebrow”. In addition, they only weigh a scant 8 oz each!
We need to keep in mind too that the removal or addition of a scope in the field will alter the balance of a rifle. That’s another reason why, in general, I like lightweight-compact scopes. There’s little to break, and they put less strain on screws and mounts when the rifle goes “kaboooommm!” due to minimal inertia.
A scope for a Big Bore should have a minimum of 4″ eye relief, and 5″ provides a comfort zone. Variable scopes will alter the eye relief as the zoom is turned for higher power. The higher the power setting, the less the eye relief! For game the size of Cape buffalo, bison, eland or moose, 4 to 6 power is surely the maximum that’s needed in a variable. At the low end, 1.5X to 2.5X would be excellent in my experience. 3 – 9 X 40mm’s are not essential for ANYTHING in the big game category inside 300 yards!
The COLOR of the scope, and its texture, is a personal matter. Personally, I prefer matte to shiny, whatever the color. High gloss black or silver high gloss, reflect way too much sunlight! The little scope on my CZ550 was only available in high gloss black at the time of purchase, so I took it, but would have preferred matte black.
Cost is also a personal matter. However, a very costly scope isn’t essential to insure that it meets all good criteria. On the other mitt, a cheap scope ($100, or less) on a Big Bore, with its powerful back-thrust, will give cheap results. For my money, I’d go at least $250 for a solid, fixed low-end power, that’s relatively light and compact with excellent eye relief. And that’s exactly what I’ve done.
Some hunters, PH’s and guides prefer NOT to scope their Big Bores. IF that decision is based on sound reasons, I’d have no issues with it. For myself, however, and I think for the majority of large game/DG hunters, a scope that fits the parameters outlined above is non-debatable.
Next time: BARRELS–length and contour.