Back to the basics — Scope tips: Part 3
by Tom Gaylord
Writing as B.B. Pelletier
This report covers:
- Droop — or downward slant
- My point is…
- I must care about this
- Scope placement
This series examines the task of mounting a scope on an air rifle and sighting it in. Part 2 addressed mounting a scope, but it didn’t cover all of the problem areas, so today I’ll continue the discussion.
Droop — or downward slant
I will say that 80 percent of all the firearms and airguns I have examined have some degree of downward slant of their bores in relation to the line of sight of a scope that’s mounted on them. And I will go on to say that half of those are so serious as to cause problems. The airgun term for this is droop. The firearm world has no term for it and is generally ignorant of the problem. The single firearm that doesn’t seem to have this problem to the extent mentioned here is the AR platform. Perhaps the designers recognized the problem and solved it through engineering. I don’t know, but ARs seem to be relatively droop-free.
I used to think droop was an airgun problem; and like most airgunners, I thought it mostly affected breakbarrels. It’s easy to think that way. But all powerplants, including those with fixed barrels, will droop. And most of them do. The barrel isn’t actually drooping like a limp noodle — it’s simply pointed down and away from the scope’s line of sight.
About a year ago, while helping another shooter at my rifle range resolve a scope problem with his Remington 700 rifle, I realized firearms were also infected with droop. This guy had his vertical elevation cranked up as far as it would go, and he was still shooting low. Obviously, the fix was to shim the scope on top of the rear ring saddle and under the rear of the scope. That makes the scope slant down. We did and it worked, but not completely. We got him up to the point of aim at 100 yards with 2 shims made from soda can aluminum pieces, but his scope was still cranked up too high.
The real solution was to swap the rings front and rear. And if this had been an airgun, we could have done that. But his rings only fit the rifle one way, so that fix wasn’t possible. What he had to do was install a universal scope base (actually 2 small bases) onto which a Weaver scope ring would clamp.
After this encounter, I started paying attention to firearms with scope issues and my eyes were opened! Barrel droop is a universal problem!
Do you remember the Schuetzen rifle I mention acquiring a few weeks ago? I had it out to the range and had to dial the scope’s external adjustments as high as they would go to hit the target 10 inches below the point of aim at 50 yards. The bases on my rifles were the wrong ones, and one of them had to be exchanged to give the scope the correct downward slant. The scope is also way off to the right, so a lot of adjustment has to be dialed-in to get the group centered. In this case, whoever mounted the scope on this rifle was not a careful worker. The holes have to be redrilled for the correct bases and to align the scope properly left and right.
My point is…
When you mount a scope, believe that you’re mounting it on a drooper. That’s what I do when I mount scopes, and I’m seldom disappointed. This tip, alone, is worth the entire price of today’s report!
Here’s why my tip almost always works. If the gun is, indeed, a drooper, you solve the problem during the mounting process. No need to take the scope off and start over. If the gun isn’t a drooper, you just gained a lot of additional useful elevation adjustment. The bottom portion of the elevation adjustment range (i.e., adjusting the reticle down below the midpoint) does not put the scope in peril like the top portion (adjusting up above the midpoint) does. You can always adjust down, but going up is where the problems lie.
There are a couple rare instances where my tip won’t work. One is when the gun slants up instead of down. The other is when the gun is such a severe drooper that extreme measures have to be taken. You’ll encounter these situations with only a small fraction of the guns that are scoped. And both can be fixed the same way — if you have the courage.
I wrote a blog about Bending airgun barrels that addresses what must be done to correct a severe drooping or upward-slanting barrel. This will also work when a barrel points to the right or left, though I believe the scope mount should be fully explored before you try bending a barrel this way.
I must care about this
I have spent a long time today discussing one point of scope mounting, so I must think it’s important. You would do well to consider what I’ve said.
The next thing I’ll address is where the scope is positioned on the rifle. It has to be close enough to your eye so the full image can be seen when the rifle’s mounted on your shoulder in the usual fashion. Some scopes, like compacts and Bug Busters, are so short they can only be mounted close enough to the eye on a few air rifles. On most rifles, the scope stop location forces you to mount the compact scope too far forward, and the image is reduced to less than optimum.
The height of the eyepiece is another consideration. Some airguns, such as the TX200 Mark III, have ultra-high cheekpieces for high-mounted scopes. All the AirForce precharged sporting rifles use high-mounted scopes.
Other guns, like the Hatsan BT65 QE I’m now testing, have adjustable cheekpieces. This makes the rifle adapt to the high scope mount it needs to clear the magazine.
Too many shooters obsess over mounting a scope as low as possible. A low-mounted scope on the right rifle is very convenient; but on the wrong gun, it is a disaster! And a large percentage of rifles are not suited to low scopes.
There’s no accuracy advantage to mounting a scope low. Shooters will tell you that the lower the scope is mounted, the less trajectory you have to deal with — and that can be demonstrated in software ballistic programs; but if you know your rifle, it makes no difference downrange. The only advantage I see to mounting a scope low is the lessening of cant as an aiming problem.
That’s my discussion for today.