Pneumatic Pnews

Monday, August 28, 2006

How best to sight-in an air rifle

by Tex Force

In our last blog, we saw what the trajectory of a pellet looks like and how scopes are adjusted to compensate for it. Today, we'll learn the best way to use this information.

One zero point or two?
It's your choice when you sight in a scope whether you get just one zero point or two. If you look at the pellet's trajectory again, you'll see that to get one zero point, you must angle (sight-in) the scope so it just grazes the top of the falling pellet at the one distance you desire. Let's say you want to zero your scope for ten yards. All you do is adjust the scope so that the position of the pellet coincides with the intersection of the crosshairs at 10 yards. At all other distances, the shot will be below the intersection of the crosshairs.

New shooters often think this is exactly what they want, because it seems so simple and straightforward. But this is not how to sight-in a scope. They either haven't thought it through, or they don't know what's going on with the pellet in flight. But, you do, because you read last week's blog (Pellet trajectory - what you need to know). You know there is a much better way to sight-in a scope.


The pellet doesn't rise, but angling the scope down makes it appear that way.


Two zero points
If you look at the pellet's curving trajectory and the scope's straight line of sight, you soon realize that, if the scope is adjusted correctly, it will cross the pellet's path at a near point. Then, the pellet will seem to rise above the intersection of the crosshairs for several yards before it falls back to the intersection again. The pellet is falling all the time, of course, but the way the scope is adjusted in this second version, it looks down through the trajectory and makes this illusion of a rising pellet.

What you also learned in last week's blog is that pellets slow down rapidly. So, the curve of a pellet's trajectory becomes rapidly more pronounced the farther it gets from the muzzle. Initial velocity and the pellet's own ballistic characteristics determine what the curve looks like, but there is a common distance at which it makes good sense to sight in your rifle.

The magic!
The magic first sight-in point for adult pellet guns with velocities in the 800 to 900 f.p.s. range is 20 yards. Let's look at one specific case. A pellet rifle with a muzzle velocity of 850 f.p.s. is sighted to strike the intersection of the crosshairs at 20 yards. The pellet will then "rise" about one pellet's width above the aim point. Where exactly that will be I'm not sure, but it's about 28-29 yards. The pellet then starts sinking again and crosses the intersection of the crosshairs at 33 to 35 yards. By 40 yards it will be one pellet's width below the intersection of the crosshairs.

What this gives you is a rifle that is essentially zeroed from 20 to 40 yards. How much better is that than a gun that can hit the aimpoint at only 10 yards? There is a drawback. The way scope mounts and scopes work, you can't adjust these numbers very much at all. You can't, for example, have a rifle that's sighted in between 10 and 30 yards. The trajectory simply won't tolerate it. It's got to be 20 yards for the near point and anywhere from 30 to 40 yards, depending on the muzzle velocity, for the far point. Throw a tantrum if you must, but the numbers I've given you are THE numbers.

Where this came from
Don't blame me. I'm just telling you the facts. This phenomenon was discovered in the 1990s by American field target shooters who set up their scopes for adjustment for every shot. They noticed there was a band of distances at which they didn't have to raise or lower their sights. When I shot a Daystate Harrier in competition, my rifle liked 20 to 30 yards. The pellet was virtually on target at any distance between those numbers. Because I adjusted the reticle whenever it was needed, it didn't matter one iota where the flat spot occurred. Everyone else had the same sight-in data as I had.

Notice, I did not mention caliber in all of this? That's because caliber doesn't matter. My .177 Harrier, shooting 10.5-grain Crosman Premiers at 860 f.p.s., had virtually the same trajectory as someone else's .20 caliber Career 707 shooting the same speed.

Monday, August 21, 2006

Pellet trajectory - what you need to know

by Tex Force

Some people think a pellet shoots straight for a while and then starts to drop slowly from the bore line. Others believe that a pellet actually rises after it leaves the muzzle, then peaks at some distance from the gun before starting to drop. Neither of these impressions is correct. A pellet begins to drop the instant it leaves the muzzle. Let's see what actually happens.

The rise is an optical illusion
Sometimes, when the sun is at my back, I have actually seen a pellet seem to rise above the aim point of my crosshairs, then sink again at some point far away from the gun. This is an optical illusion caused by pointing the telescopic sight downward through the trajectory of the pellet. You do that when sighting in to compensate for the drop of the pellet. But, when the scope is looking straight ahead, the bore is actually tilted upward and the pellet seems to rise.


The pellet doesn't rise, but angling the scope down makes it appear that way.


Pellets and bullets do not generate lift
Actually, they do generate a tiny bit of lift, but it's so small that it doesn't make them rise. What it does is retard their fall by an infinitesimal amount. The amount is too small to measure. For all practical purposes, pellets and bullets generate no lift. They fall the instant they are not supported by the barrel. If you were to shoot a pellet from a barrel that's level with the ground and were also to drop a pellet at the same instant, both would stroke the ground at the same time. The pellet you dropped would land beside you and the pellet you shot would land far away. How far, you ask? Maybe 100 yards or so.

Diabolo pellets have extreme drag
Every watch a badminton birdie (shuttlecock)? It leaves the racket at high velocity, but slows to almost nothing by the time it has gone 30 feet. That's because its skirt creates a huge amount of drag. This air-braking slows the birdie faster than anyone can imagine. Well, a wasp-waisted, hollow-tailed pellet (called a diabolo) does much the same thing. It doesn't create as much drag as a badminton birdie, plus it is both smaller and denser, being made of lead, so a pellet may go as far as 500 yards when the muzzle is elevated to shoot as far as possible. But, a solid bullet (or pellet) of the same weight leaving the muzzle at the same velocity would go about three times farther.

The drop is not uniform
Over time, the fired pellet drops to earth at a uniform rate. Over distance, however, it doesn't. In the beginning the drop is small, but as the pellet slows (and we have just learned that it slows rapidly), the amount of drop seems to become more pronounced. What is happening is that the pellet is moving less far forward with every yard it advances, so the drop starts looking more pronounced. If you see it through a scope, it's very striking.

Each pellet type is different
Heavier pellets have less drag, and as will pellets with less of a wasp waist or a shallower skirt. However, the tradeoff is that such pellets are less accurate, as well. Always put accuracy at the top of your list and velocity at the bottom, because velocity means nothing until it connects with a target.

What can this knowledge of pellet performance do for you? We'll find out next time when we see how to best sight in a pellet rifle.

Monday, August 14, 2006

Marksman 2004 Deluxe Air Pistol

by Tex Force

Looking for a nice target pistol that won't break the bank? How about the Marksman 2004 target pistol? Back in February 2006, I gushed all over Daisy's 717 pistol. I told you it was a great informal target pistol, very accurate, quiet and the power was low enough for anyone's house. Well, the Marksman 2004 is another great target pistol that has Daisy's same great accuracy but at less than half the price!

Single-stroke pneumatic
Like the Daisy 717, the Marksman 2004 is a single-stroke pneumatic. That means the pumping lever, in this case the top of the gun, is pumped just one time and the pellet is fired with that stored air. A second pump stroke is impossible; the instant the pump lever swings open, all the air from the first stroke is lost. Single-strokes are not the guns to charge for long periods of time. So pump and cock it (the same effort does both) when you are ready to shoot.


The top of the pistol swings forward and back to pump the gun once.


Mostly synthetic
The pistol is chiefly synthetic but very well made. The use of synthetic allows the gun to be almost a pound lighter, at 1.7 lbs., than equivalent metal guns.

No recoil
This pistol sits dead-still in your hand when it's fired. Think of it as a CO2 pistol that never needs CO2! Only, most CO2 pistols have heavy triggers, and the Marksman 2004 has a nice light one with some creep in the second stage. An automatic safety pops on every time the gun is cocked, so it has to be released before you shoot.

Adjustable sights
The sights are adjustable, so you can set the gun up for either a target-type 6 o'clock hold or a sporting center hold - whichever you prefer. They are a target type square post and notch, so your sighting precision can be maximized in the 6 o'clock hold.

Hard to pump
The single drawback on this air pistol is that it's hard to pump. Where the Daisy 717 is extremely easy. This more powerful pistol is smaller, so there's less leverage, which means a much harder pump effort. It's an adult gun, make no mistake.

Pellets to use
You can easily shoot half-inch groups at 33 feet (10 meters) if you're a good enough shot. And, that's what a pistol like this is all about. It trains you to shoot better. Try Gamo Match pellets, Beeman H&N Match, Daisy Quicksilver wadcutters and RWS R10 Match pellets. These are all wadcutters, so they will cut perfect round holes in the target for easy scoring.

11mm dovetail for mounting optics
The pistol has a long 11 dovetail rail for mounting optics, but you have to think of how you will pump it, since the top of the gun is also the pump handle. Your optics have to be small to give you room to pump without pressing down on them. A Daisy Point Sight mounted as far forward as possible might be the best bet.

The Marksman 2004 is a lot of air pistol for the money. It's good-looking, accurate, and has a nice trigger for this price range. If you have wanted an adult target pistol with a great price, this is it!

Monday, August 07, 2006

Should you clean your airguns?

by Tex Force

Cleaning is a question that comes up a lot. Do airguns need to be cleaned and, if they do, how to go about it. The short answer is, some airguns need to be cleaned.

Barrel
Of course airguns do not suffer from the heat and burning powder residue of firearms. They also shoot slow enough that they USUALLY do not get lead deposits, but there are a few exceptions to this. Crosman pellets are made from lead that has antimony to make it harder. They function better in repeating mechanisms that way. But, if you shoot them at speeds much faster than about 850 f.p.s., they will deposit lead in the bore, just as firearms lead up when harder non-jacketed bullets are used. Contrary to popular "wisdom," pure lead does not lead the bore until velocities exceed about 1,200 f.p.s. Then they start leading, too.

Cleaning the barrel
If you have been shooting hard lead pellets at high velocities, there is a good chance your barrel needs to be cleaned. I covered how to clean airgun barrels in the posting titled Clean your barrels for extra accuracy, so I won't repeat it here.

Cleaning the action
Many airguns are protected from the elements enough that they really don't need their actions disassembled and cleaned the way firearms do. I have a Beeman R1 with 15K shots through it, and the action is still running fine. My 1978 Sheridan Blue Streak, which probably has the same number of shots, is still going strong after 28 years. In fact, in all my shooting experience, I have seen only a few airguns that really did need to have their actions cleaned. They were CO2 and multi-pump pneumatics that had lain in the Crosman repair center for 40 years (some of them). They were dusty and really did need to be disassembled and cleaned. I haven't seen a gun that was used that ever did. Perhaps, if someone stored a gun in a barn next to the hayloft, it might get that dirty, but I haven't seen it.

I take that back. There is another class of airgun I have seen that needed immediate stripping and cleaning. That was the gun that someone had tried to "slick up" by greasing the action. I have seen some pretty gross guns that were "tuned" in this way. They look great on the outside, but the insides are swimming in grease. They needed to be stripped and cleaned, then lubricated properly to have their power restored.

Cleaning the trigger
Triggers are a whole different story. If someone has lubricated them, they probably do need to be cleaned. And, some new triggers come over-greased from the factory. I clean them with rubbing alcohol and cotton swabs. For the really tight areas, a swab won't reach; a paperclip can be bent into a scraper to scrape out the grease.

Cleaning the finish
Many airguns have synthetic parts and finishes that never need cleaning. These are best wiped down and that's all. The Daisy Red Ryder is one such gun. On the other hand, the Gamo Hunter Elite has a blued finish and needs to be wiped with a silicone cloth to give it protection.

Long-term storage
I know I've said this before, but DO NOT store any airgun in a foam-lined case for a long time. A week is about where a long time begins. The foam in those cases absorbs moisture from the air, and your guns will have all sorts of moisture problems if you forget this rule.

So, do you need to clean your airguns? The answer depends on what you have been doing with them, and YOU must be the judge!