How to mount a scope: Part 5

by Tom Gaylord
Writing as B.B. Pelletier

Part 1
Part 2
Part 3
Part 4

This report covers:

  • More scope stuff
  • Swap the rings
  • Spiraling pellets
  • What to do about spiraling pellets
  • Misaligned scope
  • How to correct the misaligned scope
  • Setting up a rifle
  • BB did NOT say all bundled scopes are bad!
  • Scope stiction
  • Sighting-in for one distance
  • Summary

More scope stuff

While we are finished with mounting a scope, there is more to tell. A lot of it does come to the forefront when you mount a scope, so it is germane to this discussion. We have touched on some of it before, but today I hope to tell you how to deal with it.

Swap the rings

This is a trick that can help resolve many of the problems we will see today. It’s also one of the big reasons that I prefer 2-piece rings to 1-piece. Someone asked last time what can be done when the scope’s axis is out of alignment with the barrel. Well, that is often the case. The way you find it out is — after you sight the rifle in you try to shoot at different distances and discover that your pellet is off to one side or the other. What can be done? read more


Scope dope — I hope! Part 4

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1
Part 2
Part 3

This is an ongoing series about scope questions and issues. Blog reader David Enoch asked for it originally, but many other readers have jumped in since it began. Today, I’ll talk about adjustable scope mounts.

First things first read more


Can a fixed-barrel airgun have barrel droop?

by B.B. Pelletier

This report is in response to a comment Pyramyd Air got from a customer who doubts that fixed-barrel airguns can ever droop. His position is that they can only have droop if the barrel is heated in some way (as on a firearm that fires very fast) or if the gun is assembled in a shoddy fashion.

He said he believed barrel droop is only commonly found on breakbarrel airguns, which is why he said he would never own one. He thought that droop was mostly caused by the metallurgy of the barrel.

Today, I’d like to address the subject of barrel droop in detail. It can be caused by many things, but poor metallurgy isn’t one of them. Barrels do not bend from cocking, despite what some people may think. It is true that a barrel can be bent by human force, but the force required to do so is much greater than the heaviest cocking effort on the most powerful magnum airgun. So, poor metallurgy is not a contributor to barrel droop.

What is barrel droop?
I will explain what barrel droop is in detail later in this report. For now, I’ll just say that barrel droop is a condition in which an air rifle shoots so low that the scope cannot be adjusted to hit the target.

You must understand that most scopes cannot be adjusted all the way to their highest elevation settings and still operate correctly. This will differ from scope to scope, but generally most scopes do not work well when adjusted above three-fourths of their maximum elevation. It’s imperative that they get on target before reaching that height, and a drooping barrel can prevent that.

History
Throughout the first five decades of spring-piston air rifles, no one ever heard of barrel droop. It was a non-issue. That was because nobody bothered scoping their air rifles.

The sights on most breakbarrel guns are attached to the barrel, both at the front and rear, so they’re in line with the bore — as long as the bore is drilled straight through the barrel, which it seldom is. The amount of misalignment is usually measured in the thousandths of an inch — an amount the sights can easily account for.


With both the front and rear sight attached to the barrel, there’s less chance for misalignment.

In the 1960s, retailers began attaching scopes to airguns to sell more of them. Firearms had been using scopes for some time, and the general belief among shooters was that scopes extracted the maximum accuracy from any gun.

But scopes had a problem, as well. They were attached to the spring tube of the gun, which isn’t integral with the barrel on a breakbarrel airgun. For the first time, the alignment of the spring tube and barrel came into question.

It soon became known that most breakbarrel guns have a barrel that slants downward from the axis of the spring tube. In the 1960s and ’70s, breakbarrels were hand-selected for scope use when they exhibited less slant than other guns of the same model. You can read about this selection program in both the Air Rifle Headquarters and Beeman catalogs of the period.

What those catalogs didn’t address was the fact that fixed-barrel airguns can and do sometimes have the same barrel slanting problems. They didn’t address it because, at the time, scoping airguns was brand new and not that much was known about it. The people scoping the guns often installed simple fixes, such as shimming the rear ring, and didn’t even think about why they were doing it.

Why the barrel droops
The comment that prompted this blog went on to say that barrel droop was caused by poor metallurgy. Evidently, the writer thought that “droop” referred to a barrel that was curved (or bent) downward — which is not the case. The term “droop” doesn’t refer to a barrel that is somehow curved. It means a barrel that points in a direction away from the sight line, so the axis of the bore and the sight line are diverging. To correct for this droop, the scope has to be repositioned to align with the axis of the bore.

We all understand that a pellet starts falling the moment it leaves the muzzle. The farther from the muzzle it goes, the faster it falls; so the line of flight is actually an arc, rather than a straight line. To align the sight line of the scope with the axis of the bore, we have to align the scope to look downward through the line of flight. To be effective — that is to get any distance over which the pellet is on target — the sight line is made to pass through the arc of the pellet twice — once when the pellet is close to the gun and again when it’s farther away.


The scope is angled down through the pellet’s trajectory. This illustration is greatly enhanced for clarity. This alignment is done the same for firearms and airguns, alike.

But the question is, “Why does the barrel point downward?” With a breakbarrel, it’s usually because of how the breech locks up at a slight angle that causes the downward slant. Some guns, most notably target breakbarrels, overcome this with barrel locks that cam the breech tightly against the spring tube in a straight line. Most guns rely on the spring-loaded detent to both align and hold the barrel during firing. If there’s a weakness, it’s at this point. When a breakbarrel with an unlocked breech fires, the barrel tends to flex in the direction the barrel is hinged. If the barrel broke upward to cock, the problem would be reversed and we would have a barrel “climb” problem.


A breech lock like the one on this HW 55 ensures that the barrel always aligns with the sights — provided the rifle is designed that way.

Do you now understand that the barrels are perfectly straight, and it’s just the angle of the bore’s axis relative to the line of sight that creates the drooping problem? Good, because that’ll make the following easier to understand.

What about underlevers and sidelevers with fixed barrels?
How can a fixed-barrel rifle have droop? Easy — the barrel isn’t attached to the gun with the bore parallel to the line of sight. Presto! Automatic sighting problem. Or the scope base that’s attached to the spring tube may not be aligned with the axis of the bore. Or the bore may be drilled off-center; and although the outside of the barrel is parallel to the sight line, the bore’s axis isn’t. Any of these three things can happen.

Bore not drilled straight
This is very common. It’s extremely difficult to drill a deep (long) hole straight through a steel bar. The drill bit can wander off-axis as it bites its way through the steel, or it can be off-axis all the way through the bore if it isn’t correctly set into the holding fixture before the drilling begins. I’ve had barrels with bores as much as a quarter-inch off-axis with the outside. Granted that’s extreme and uncommon, but it demonstrates the possibility.

The only way a barrel-maker can ensure concentricity of the bore to the outside of the barrel is to machine the outside of the barrel after the gun is rifled.

Barrel isn’t aligned with the spring tube read more


2012 SHOT Show: Part 2

by B.B. Pelletier

Photos by Earl “Mac” McDonald

Part 1

This is the second of my reports on the 2012 SHOT Show. There will certainly be at least one more after this, and perhaps even more, as there’s simply too much new information to pack into a single report.

The state of the airgun industry in 2012
Before I get to some specifics, I want to make a general observation. This year’s SHOT Show was different for me in a major way, because I saw for the first time that firearms shooters are beginning to understand airguns as never before. In the past, I always had to start my explanations with the cooling of the earth’s crust and then progress through the age of the dinosaurs because each firearms person I talked to thought of airguns as either toys or BB guns. This year, a lot of them were clued-in on what’s happening. They weren’t surprised by the accuracy we get, and they knew about big bores. A lot of them had some airgun experience and more than a few asked me the same kind of questions that I get from long-time readers of this blog.

That tells me the day of the airgun has finally dawned in the U.S. Instead of 25,000 to 50,000 active shooters (at best!), we will now see an influx from over 5 million active firearm shooters who are ready to augment their shooting experience with airguns. I’m already getting calls and emails from state departments of wildlife resources, asking about the issues of incorporating airguns into their hunting seasons.

It has been a long haul to get to this point, but we’re now seeing the start of the harvest of all the work that’s been done over the past 40 years — starting with Robert Beeman in the early 1970s. The job is now to manage this growth and provide useful information to the tens of thousands of new airgunners who are flooding in the doors.

Let me reflect on how the industry seems to be reacting to this trend. Some companies have been on board for many years and are poised to ride the new tidal wave of business as far as they can. Other companies are aware that airguns are very hot, but they’re foundering, trying to understand them. Let me say right now that it’s not as easy as you think!

The readers of this blog are among the most clued-in airgunners in the world. But they’re unique, and they do not represent the true market. The demographic of a new airgunner is a man (usually) in his late 20s to late 40s who is most likely a fan of AR-type rifles and Glock-type pistols. He wants repeaters, semiautos and he thinks that a five-shot group is the gold standard of any gun. Velocity impresses him, and he isn’t comfortable with the term kinetic energy.

Things like good triggers and good sights are not an issue with this customer until he experiences bad ones. His ARs have decent triggers off the rack, and he can choose from many drop-in triggers that are much better. When he encounters a spring-piston gun with a horrible trigger that cannot be easily modified, he’s surprised.

He does not use the artillery hold, and he equates all airguns to be alike in terms of performance. When he learns about precharged guns, he’s put off by the additional equipment he must buy. Spring-piston guns seem the best to him for their simple operation, and he doesn’t appreciate the fact that they’re also the most difficult airguns to shoot well.

That’s the customer who’s coming to airguns today, so that’s the person airgun manufacturers have to deal with. If you have wondered why many of the new airguns are what they are — this new-customer profile is the reason.

Okay, I’ve talked about those companies that get it and those that are struggling to understand. There’s one more type of company out there. I like to call them the “gloom and doom company” or the “zero sum company.” They’re firmly entrenched in the 1970s and cannot take advantage of this new windfall of business. They either fired their engineers years ago or they let them all retire, and now they couldn’t build a new airgun to save their lives. As far as they’re concerned, there are only 25,000 airgunners in the United States and it’s the NRA’s responsibility to identify and train them so these companies can sell them some guns.

They think of marketing in 1950’s terms, when a simple paint job and some sheet metal was enough to create a new product. Their “secret” business plan is to buy guns made by other manufacturers and have their name put on. If you’re a collector, better buy up the guns these guys sell because in 10 years their name will be a memory.

That’s enough of the big picture. Let’s see some more products.

More from Crosman
Many of you saw the list of new Crosman products Kevin posted last week, so the few that I show here are by no means all there is, but they’re the highlights. Crosman had about half the new airgun products at the entire SHOT Show.

New tan M4-177 and carry handle
The M4-177 multi-pump that I recently tested for you is going to be very popular this year. Crosman is also offering it as an M4-177 Tactical air rifle with a new carry handle that replaces the rear sight for improved sighting options. I think this gun will be in their lineup for many years to come.


The M4-177 now comes as this tactical model in tan with a carry handle.

I mentioned to Crosman’s Ed Schultz that this rifle looks like the A.I.R.-17 of the 1990s, but done better. He said he always wanted to update that design, and that is exactly what this is. So, what he said next came as no great surprise.

I shared my thoughts on a 2260 made as a multi-pump in .25 caliber, and Ed told me that was how the rifle was originally created (not in .25, however). The CO2 version was an afterthought that got put into production, while the multi-pump version languished in the Crosman morgue. I told him that I thought the time was ripe to bring it back as an upscale hunting rifle, and he seemed to agree. We can only hope.

Carbon fiber tank
As Crosman extends their capability into PCP guns, they know shooters are always looking for better options for their air supply. Besides the new butterfly hand pump I showed you last time, they’ll also be adding a long summer-sausage black carbon fiber tank with increased capacity over their current tanks. This is a 300-bar tank that has 342 cubic-inch capacity. It comes in a black nylon carrying case with sling for field transport.


More air for you! New Benjamin carbon fiber tank will help you take your PCPs further afield.

Benjamin Nitro Piston breakbarrel pistol
The Benjamin NP breakbarrel pistol certainly has people talking on the internet. This is the first commercial gas spring application in a pistol, I believe. The most distinctive feature is a cocking aid that can either be detached or left in place while shooting. That reminds us that this pistol is going to be hard to cock, but I’ll test one for you so we’ll all know just how hard.


New Benjamin Trail NP pistol is a breakbarrel with a gas spring. The cocking aid can be detached or left in place while shooting.

Crosman 1720T PCP pistol
Everybody was ready to jump down Crosman’s throat for creating the 1720T PCP pistol. They wondered with the .22-caliber Marauder pistol and the .177-caliber Silhouette PCP pistol already selling, why was this one needed? As Ed Schultz explained it to me — this one is for field target. It’s a .177 (naturally) that produces just under 12 foot-pounds through a shrouded Lother Walther barrel. It can be used for hunting, but field target was its primary purpose. They worried about the shot count with the Silhouette; but with this one, power was the criterion. Look for about 800 f.p.s. with a 7.9-grain Premier. And the trigger is the same as the Marauder, so excellent operation there.


The new Crosman 1720T PCP pistol is meant for field target competition. It will also work well for hunting.

Crosman MAR 177 PCP conversion
The Crosman MAR-177 PCP conversion is another new product that has a lot of people talking. This AR-15 upper converts your .223 semiauto into a .177 PCP repeating target rifle. Because it’s on an AR platform, almost everybody expects it to be semiautomatic — including those who should know better. This rifle is a bolt action that cocks and loads via a short pull on the charging handle.

This conversion is an Olympic-grade target rifle for a new official sport that Scott Pilkington and others have been promoting for several years. It will take the U.S. battle rifle back into the ranks of target shooting. However, the look of the gun has many shooters totally confused. I was even asked at the show if I thought Crosman should have come out with an “everyman’s” version of the gun first. That would be like asking whether Feinwerkbau missed the boat by not first making their 700 target rifle in a $300 version for casual plinkers.


The MAR-177 PCP conversion is an upper for your target-grade lower. Plan on investing about another $1,000 in a good lower if you hope to compete.

Crosman TT BB pistol
It’s all-metal and a good copy of the Tokarev pistol. The weight is good and the gun feels just right. This will be one to test as soon as possible.


Crosman’s TT Tokarev BB pistol is realistic and looks like fun. read more


A shrine built for a Feinwerkbau 124 – Part 11

by B.B. Pelletier

Part 10
Part 9
Part 8
Part 7
Part 6
Part 5
Part 4
Part 3
Part 2
Part 1

Well, here is our old friend, the San Anselmo Beeman 124, again. Today, I’ll address the scope problems I was having the last time I tested the rifle for accuracy.

You may recall that I suggested that the front and rear rings be swapped to see if that would alter the amount of down angle the rifle appears to have. One reader was appalled that anything manufactured could be that far off from true, but believe me, it doesn’t take much. I’ve seen this trick work many times in the past. However, I failed to mention that three inches is a bit excessive to try to correct this way. This trick is more for those who optically center their scope and have a half-inch problem at the first point of intersection.

However, I did remove the rings and swap the front for the rear. Because these are two-piece rings I could also turn one ring at a time, giving me six different permutations of the setup, I believe. But three inches of change is so major that if it doesn’t come by swapping positions, you might as well look elsewhere.

Well, I was right. Swapping the rings did make a big difference. Only the difference went the wrong way. Now the pellet was striking the target four inches below the aim point, using the exact same scope with no adjustments. So, this set of rings was history. No amount of shimming would ever be able to make up an angular difference that large.

However, I had an ace up my sleeve. I’d visited the AirForce factory and asked to borrow a BKL drooper scope mount, and they happily complied. So, now I had the BKL 260 with .007 drop compensation to try out. This is a one-piece mount and it comes with simple instructions for which way to mount it. However, I did encounter a problem. This BKL mount is too low to allow the 50mm scope I had been using to clear the 124 spring tube. And you’ll recall that I have to use a BKL mount because of the 124’s non-standard scope stop system. I have mounts that will work with it, but you can’t buy them, so I’m not testing them here.

The solution was to use another scope, and all I was trying to do was ascertain that there was a scope mount and ring set in the world for this rifle — a vintage 124 with a large barrel droop. So, I picked a BSA 3-9×32 scope that didn’t have parallax adjustment. As a result, I had to run it at five power or the target was too blurry to see well.


The BSA scope fits well in the BKL drooper mount. I could have gotten away with a 40mm objective, if I’d wanted.

Even with all that disadvantage against me, I proved the concept. The 124 and this new scope adjusted on target perfectly with no problem of adjusting the elevation knob too high.

So, I shot one group of 10 Crosman Premier 7.9-grain pellets and then another. Sure enough, the problem has been solved.


Good group, properly centered and 10 tight shots at 25 yards with Crosman Premier lites.

I’m removing the scope from the gun, because the only reason I scoped it in the first place was to conduct the Silver Jets accuracy test. That’s over now, so the 124 can go back into its sarcophagus, except for one more tuneup that will employ the newest Pyramyd Air 124 piston seal.