Part 1
Part 2

This report covers:

  • Accuracy
  • Workaround?
  • Ring height versus zero?
  • What to do
  • Rant over
  • Scope ring height
  • Clearance
  • What does scope height affect?
  • Summary

Today we’re going to get into scope rings pretty deep. And right off the bat I have the subject for you. The report on scoping the Gamo Arrow brought up some interesting things that we need to consider before we begin. The first is accuracy.

Accuracy

Putting the pellets in one hole is the definition of accuracy. Where those pellets land is a different issue that we are considering in this report.

The Gamo Arrow that I scoped was shooting too low. It was putting them all into the same hole but the hole was in the wrong place. What needs to be done now is to adjust that scope to hit the target at which I aim — to hit the aim point (or close to it, so the aim point isn’t destroyed, making me guess where it was). The Gamo Arrow rifle is already accurate, because it shoots all its pellets to the same place. 

Workaround?

When I said “workaround” in that report I wasn’t talking what you do about scopes that can’t be zeroed. I was referring to the things I do so I can complete a test. Rain or shine, everyone expects a new report on this blog every working day of the week. So I often don’t waste my time trying to do all things right. I WORK AROUND the problem, if I encounter one, knowing that the next time I test that rifle there is an issue to be resolved. 

Ring height versus zero?

Does the height of the scope rings determine the zero of the scope? NO! NO! NO! Ring height has very little to do with the scope’s zero. Low rings are not what are needed when a scope shoots too low. A downward angle on the scope is what we need. And we can get that regardless of the ring height.

And here is a comment to that report that I have to address.

“I sincerely think, and I hope Gamo read BBs great posts and our comments. If they can get these [barrel droop] issues solved, they truly have a great beginner rifle at hand which will probably also be bought by more seasoned shooters.”

Resolve the barrel droop issue? If Gamo ever could do that they would be the first company to do so. Winchester, Mauser, Weihrauch, BSA, Remington and all the AR-15 makers haven’t resolved it. Perhaps Whiscombe made air rifles without droop and I may have seen a couple TX200s that didn’t droop, but darn few other makers of firearms or airguns make rifles that don’t droop.

What to do

The thing for you to do, instead of looking for that unicorn air rifle that doesn’t droop, is to plan what you will do when you discover how much droop your air rifle has. Or, you can just show up at the range and let BB Pelletier fix it for you, as I already have done many times. Guys — THIS is why I always shim the lower ring saddle under the rear scope tube. 

I have been trying to get this point across in this series. Please reread the following text from Part 2:

… nearly all firearm rifles shoot low! Yes, they do. And, because of that, they need scope mounts (rings) that have some rear elevation to get them up on target. When gunsmiths were mounting scope rings by hand they were taking care of this in the job they did. They lapped the rings after mounting them so they put the scope on target at a specified distance that was usually 100 yards.

The worst firearms with a down angle are the AR-15 platforms that actually have scope rings that produce X number of minutes of down angle. They sell them for long-range shooting, but most ARs need them to keep the scope in adjustment at 100 yards. Without them the scope either has to be shimmed in the rear or it gets adjusted so high that the erector tube return spring relaxes too much and the scope won’t hold zero. Shooters blame the scope when it’s the rings that are at fault. I will say that premium scopes can be adjusted higher than cheaper scopes, so the cheap scopes get the rap for not doing the job when all along it’s the rings.

Shop PCP Rifles

Rant over

BB doesn’t get on his soapbox very often, but this subject is one that puts him there. When I worked at AirForce I took all the technical calls, and the two questions that were the most common were, 1. Why can’t I pressurize my AirForce Condor air rifle tank to 3,000 psi and get decent velocity? and 2. I have tried three scopes on your rifle (at this point the rifle was always OUR rifle) and it still won’t shoot a group.

For question number one after a half hour conversation they either understood that their power curve happened between two numbers that did not start at 3,000 psi or else they sent the rifle back. The funny thing is, if their power curve came on at 2,700 psi on their Condor and gave them the 20 powerful shots that we advertised (.22 caliber Crosman Premier pellets going out at over 1,200 f.p.s.) some people were still not satisfied. In essence they said, “I paid a lot of money for a powerful air rifle that gets pressurized to 3,000 psi and this one doesn’t! I want my money back!” That’s like getting angry because your speedometer says you are going 100 kilometers per hour when you know darn good and well you aren’t going any faster than 62 miles per hour. Look it up.

By the way, Americans, when you travel to Germany next year be sure to visit the city of Ausfahrt. It’s huge! You’ll find exits to it off the Autobahns all around the country.

For question number two, if the customers followed my instructions and dialed their scope’s elevation down 60-80 clicks, their rifles suddenly became “accurate.” The problem then was how to get those tight groups back up to their aim point. That problem took two half-hour conversations at different times, because they first had to do the scope adjustment thing that I told them (and you) about just now. Then they had to call me back after discovering that their rifle was accurate so I could tell them how to adjust their impact point up to hit the aim point. Either that or I was as dumb as a bag of hammers and they returned the rifle.

Scope ring height

What, then, does the height of the scope rings height affect? Why are there scope rings of different heights? Let’s start with the big one — clearance

Clearance

Before airguns were scoped there was a clearance problem with firearm rifles. The most common problem was the bolt handle came up so far that the scope prevented it from opening all the way. Anyone who has ever scoped a Russian Mosin Nagant rifle knows what I’m talking about. Their bolts open with a 90 degree turn to the left. That puts the bolt handle straight up.

Mosin scoped
When the Mosin Nagant bolt is opened (it’s closed in this picture) the handle comes straight up. If you don’t modify the handle , the scope has to be mounted ahead of the bolt for clearance. This is a UTG scout scope with an extra-long eye relief for exactly this problem.

The problem with mounting a scope high is your head then has to get high enough to see through it.

Tom shoots Mosin
See how high my head has to be to see through that scope?

The Russians did not design the Mosin to be scoped. They designed it to accommodate the many different ethnic groups found in the Russian Army. One consequence of that is the buttstock drops more than any western military rifle. That exacerbates the high scope problem.

The Soviets solved the bolt issue for their sniper rifles by lowering the bolt handle. That allowed the scope to be mounted farther back and closer to the shooter’s eye.

sniper Mosin
This Hungarian Mosin sniper rifle has the lowered bolt handle so the 3.5-power sniper scope can be set back above the receiver.

Air rifles can have clearance issues as well. Many rifles that use a rotary magazine have the magazine sticking up above the top of the receiver. It has to be cleared by the scope and that often means using high rings.

S510 scoped
This Air Arms S510 illustrates the problem of scoping a repeater very well. The scope has to clear the rotary magazine that can be seen sticking up above the flat receiver. The dimensions of this scope put its turret exactly over the magazine. This forces two things — high scope rings and two-piece scope rings.

So clearance is one big reason for high rings. Another reason is also a clearance issue, but it’s clearance for the shooter rather than for the scope. AirForce airguns illustrate this very well.

The straight line of the air tank on an AirForce air rifle that is also the rifle’s butt pushes the shooter’s face up high. Also, your sighting eye has to get around the round air tank in order to align with a scope that is centered on the rifle’s frame. A flat buttstock makes this easier.

I used to demonstrate to dealers at the SHOT Show how to hold AirForce rifles to handle the scope height issue. It takes a modified hold with the bottom tip of the buttplate in the top pocket of the shoulder, and once you have it, the rifle is as stable as any rifle ever is. Since there is little to no recoil, this isn’t a problem.

Tom shoots TexanSS
BB fatface sights an AirForce TexanSS. There is no scope mounted but look how high my sighting eye has gone. The scope has to be up there to meet me, and that means high mounts.
And by the way, this picture illustrates why I bought a Labradar chronograph — so I don’t shoot it!

What does scope height affect?

A high-mounted scope is just as precise at all distances as one that’s mounted low. However, if you cant (tilt) the rifle at all, the high-mounted scope will be affected more than one that’s mounted lower. That is the major advantage of a low-mounted scope. You can read about this in my blog report called What cant does.

You can also fit a scoped rifle that has a low mount into a rifle carrying case easier. That’s a minor concern, but a very real one.

Summary

I hadn’t initially planned on going into so much detail about ring height today, but as I wrote the subject just kept expanding. I decided to just run with it to the end instead of condensing things. I hope I have written it in a way that’s easy to understand.