Accurizing Your Firearm: Part I - Optics
When it comes to accuracy in big game rifles, there are two extremes. On the one hand are the hunters who go to a neighborhood sandpit the day before their hunting trip, set up a cardboard box at 25 paces and blast off a half a dozen shots. If the majority of the bullets hit the box, then the rifle is deemed satisfactory for yet another season.
At the other extreme are the marksmen who tote bull-barreled guns topped with enough optics to supply a glass factory for a week of full production. They practice controlled breathing, nestle their guns into sand bags and spend half an hour squeezing off a shot at a target so far away that you have to rely on imagination and blind faith to know it's really there.
Somewhere between the two extremes are the majority of centerfire shooters. I figure I fall about halfway between; I'm a big game hunter and I take pride in my ability to pull off a tough shot at game. And I've learned that shooting ability is dependent partly on acquired skills, partly well tuned equipment and, in large part, on confidence.
Just about any gun, straight out of the box, shoots fairly well, but it can't be depended on to deliver a particularly difficult shot when called upon for that once-in-a-lifetime trophy. That doesn't mean that most guns are shoddily made. Rather, it means that most guns require a few modifications to fine-tune them; the manufacturer could provide these same modifications, but the cost of the additional labor would drive the price up to the level of a custom-made gun and it would no longer be competitively priced on the mass market.
To demonstrate how an off-the-rack rifle can be upgraded to the level of a gun that shoots every bit as accurately as a custom-made firearm, I took a standard grade pre-2006 Winchester Model 70 Lightweight in 270 Win. caliber and turned it into a big game rifle that shoots as well as any custom gun worth two and even three times the price. Starting with this issue, I'll deal with sights and scopes and, in subsequent issues I'll discuss bedding, triggers, recoil reducers and the ammunition.
It's important to match the bases to the size of the front objective and still
maintain solid contact between the cheek and the stock.
The Case for Glass
First step was to select and mount a sighting system on the gun. First off, I maintain that it makes no sense whatsoever to stubbornly cling to iron sights. Modern telescopic sights are faster to use and infinitely more accurate than open sights on any gun which throws a single projectile, shotgun included. It's true that some marksmen can pull off great shots with iron sights, but almost anybody can shoot as well or even better with a scope.
Consider this, to aim with open sights the shooter must line up three points of reference perfectly--the back sight, the front sight and the intended point of impact. For the eastern whitetail hunter who often hunts heavy brush and encounters his game at ranges of 30 to 75 yards, that's relatively easy, given adequate lighting conditions. But move that deer out to 125 yards under heavily overcast skies in late afternoon and the shot becomes a matter of guesswork.
It's cold and damp and the light isn't so good. This is when good optics makes a huge difference.
With a scope, the shooter simply places the crosshair on the target and squeezes off the shot. Depending on the ballistics of the particular gun and the distance, an adjustment for bullet drop might be necessary, but a 30-yard shot is as easy to take as a 125-yard shot, minus the guesswork. For close range eastern deer hunting and black bear hunting, a low-power variable with a bottom end magnification of 1.5 is perfect for fast, close shots while the upper end magnification of 4.5 comes in handy for the longer shots. For long range, the same concept holds true, except that you'll want to use a 3x9 variable. Telescopes with even higher magnification are available, but there comes a point where the weight of all that glass becomes a consideration.
In selecting a scope as well as the mounts, buy the best you can possibly afford. There is no such thing as a bargain scope. It costs a given amount of money to produce an acceptable scope and so it stands to reason that, in order to produce bargain-priced scopes, the manufacturer must cut corners. Most often this is accomplished either in the construction and assembly of the tube components or in the quality of the optics, frequently both. One problem is that the low end scopes cannot withstand the recoil of today's firearms on an ongoing basis and, after a year or two, the hardware fatigues, seriously compromising accuracy.
Lens quality is another consideration. All lenses start out as a solid block of glass which is first cut, then polished to remove the fine scratches left by the cutting process. The further this polishing process is taken, the better the glass can transmit light. Multi-coating, in which the surface of the glass is coated with multiple layers of magnesium fluoride, enhances light transmission to some extent and effectively improves the quality of the optics, but the fact remains that a scope with well polished, multi-coated lenses will transmit light better than a scope with only moderately polished, multi-coated lenses.
Next time you're in a gun shop, compare the optics of a low end scope to that of an expensive model by holding them up side by side and looking through first one, then the other. Don't look towards the window or at a light, rather, point them towards a dimly lit corner of the shop; the difference in clarity and contrast should almost jump out at you.
Front objective size also determines the amount of light gathered by the telescope, but there tradeoffs to be made. A big front bell provides a huge advantage if you're shooting mostly in the last few legal minutes before dusk, otherwise you're carrying extra weight and probably have to go to higher mounts for the objective to clear the barrel. More on that later.
Besides providing better visibility, the higher end scopes tend to have better crosshairs, an important consideration if you hunt in situations where long-range shots are occasionally called for. This aspect--known as reticle subtension in the trade--becomes readily apparent on the shooting when you peer through the scope at the shooting range; at 100 yards, the cross hairs of low end scopes cover slightly more than an inch of the target, making it difficult to punch an acceptable grouping.
The counter argument is that a heavy cross hair is desirable in dense cover and I concur completely, provided the optics are clear to begin with. An alternative is to use the duplex design which features heavy posts (covering 0.9 inches at 100 yards, 9X power) and fine crosshairs (covering 0.3 inches at 100 yards, 9X power). The crosshairs are easy to locate for fast shooting and yet fine enough for long range shots.
But no matter how good your scope, it won't shoot worth a plugged nickel if you don't mount it right. Invest in a set of good bases and rings that are made specifically for your gun. Steel bases cost about twice as much as aluminum, but they will stand up to recoil better. Also, make sure that the rings are high enough so that the bell at the front of the scope clears the barrel; usually compact scopes will take the low rings while scopes with large objective (front) lenses will require high rings. The firearms dealer should be able to suggest the proper bases and rings for your particular rifle/scope combination.
At all costs, avoid both the tip-off style mounts and the see-through mounts; neither serves any valid purpose if you've matched the scope to the gun, game and terrain. My experience with tip-off mounts has been that I traded accuracy for the option of using the gun's iron sights, which I never did. And the problem with see-through mounts is that they force the shooter to lift his or her cheek off the stock when peering through the optics, thereby sacrificing accuracy and the ability to quickly acquire a sight picture on all shots taken with the scope.
The first step in mounting a scope properly on a new gun is to remove the screw plugs which usually fill the pre-drilled holes in the gun's receiver. Next, lay out the bases on the gun to make sure that you have, indeed, been sold the right ones for your gun and that no mix-up occurred along the line. If everything matches, start cleaning all areas of metal to metal contact--the areas where the bases touch the gun's receiver and where the rings attach to the scope--as well as the screws and screw holes with a commercial degreasing agent.
Start by attaching the bases to the gun; apply a thread adhesive like Loctite to the screw holes, then tighten down the screws snugly. Be careful not to apply so much torque that you strip the threads or head. Tap the screw driver lightly with a small mallet before the screws are given the final tightening to ensure that the threads are in full contact.
Use a Dowel
Next step in the procedure for most mounts and rings is to attach the bottom half of the rings on the mounts. If you've properly chosen the scope and mounts, the front (objective) bell should clear the barrel; if it doesn't, you'll have to get higher mounts. Assuming that everything fits, apply the bottom of the rings to the mounts. At this point it is essential to verify that the front and rear rings line up to prevent damage to the scope. This is not a matter to be trusted to eyeballing the alignment. A 12 inch length of hardwood dowel of the same size as the scope tube diameter-most scopes are one inch diameter, some are 30mm or about 1.2 inch-works just great. Lay it across the two mounts with the bottom half of the rings attached. If the rings are lined up, they'll cradle the dowel perfectly; if not, it's a simple matter to adjust the position of the rings until they do.
A 12-inch length of dowel can be used to check the proper alignment of the rings,
but I had this set of pointed stainless steel rods made for that purpose.
Once you're happy with the alignment, set the scope in place of the dowel and apply the top part of the rings.
Now, snug the screws down just enough to hold the scope in place.
At this point, adjust your eye relief--the distance between the lens and your eye--to a comfortable position. The eye relief on most good scopes these days is between three and four inches and, if you've positioned the scope properly, you should get an instant view through the tube without having to creep back and forth on the stock. At the same time, also make sure that the horizontal reticle is truly horizontal. With everything properly in place, begin tightening down the rings, turning each of the screws a half turn at a time. Again be careful not to strip the treads of the screw heads.
Final step is to sight in the gun. I use a bore-sighter to get the shots on target and then do the final sighting in at the 100 yard range. Don't expect the gun to punch a clover-leaf group on the first outing; my Model 70 Lightweight test gun produced two- to three-inch groups which I suspect can be tightened simply by making sure that the stock-to-barrel fit and the bedding of the action. More on that in the next issue.
George Gruenefeld has been hunting big game for over four decades and his travels have taken him to several continents. Most of the time, though, he concentrates his efforts on the Prairies and mountains of Western Canada.