Air Rifle Vs Scope

[W.R.Buchanan]

I have had some interesting results with Airgun Scopes and I have several. My first air gun scope was mounted to my HW 35 (predecessor of the R1) and it was a Bushnell 4X .22 Rimfire scope. I put thousands of rounds thru that gun with that scope mounted and it lays in a box in my shop as we speak. I took it off to put a Peep Sight on the gun for practice shooting or else it would still be on that gun.

I have a Leapers 1-4 Airgun scope that survived 1500 rounds on my mini145 only to cack in less than 100 after being mounted to my R1.

I have a Burris 4X mini which is labeled Airgun Scope and it has never shifted Zero once in 20+ years.

I replaced the Leapers Scope on my R1 with a 1-4X Leupold VX1 but I called Leupold first to make sure it could take the recoil. They stated it would and if I ever had a problem they'd fix it free. It was $199 from Midway with free shipping.

The one thing about heavy recoiling Airguns is you must have a Scope Mount that is Keyed or pinned to the receiver.

The $60 mount I got from Pyramyd for my Leupold had four pinch screws which I had torqued to 40 IP and it moved a measureable .005 with every shot. the $14.95 cheapo mount from Pyramyd that replaced it works perfect simply because it has a stop screw that engages one of the vertical holes in the receiver that are put there for this reason.

I don't consider $200 for an optic for a $600 rifle to be out of line. I would have preferred the Leapers 1-4 had lived up to it's expectations as I liked that scope.

My .02

Randy

[nicholst55]

The one thing about heavy recoiling Airguns is you must have a Scope Mount that is Keyed or pinned to the receiver.

Randy

I bought a recoil stop for an inexpensive air rifle scope (Bushnell), and it has stopped the scope from creeping forward. I can't recall where I bought it, but it was only a few bucks at the time.

[jcwit]

If your rifle doesn't come with a stop this is what you need.

~http://www.opticsplanet.com/sun-optics-11mm-recoil-stop-block.html

[W.R.Buchanan]

Interestingly though the Williams Peep sight I put on my HW35 has only two small pinch crews and it has never mover 1 iota. It has virtually no mass and as such there is nothing to transfer the inertia to.

So everybody is clear on this Two Stage Recoil thing.

The Initial Recoil impulse is caused by the spring pushing the piston forward when the trigger is pulled. It is to the rear.

The Secondary Impulse is from the piston hitting the front of the air cylinder, which jerks the gun forward.

Fairly good article in the Aug Shotgun News about the HW35 which is still in production today and considered one of the best spring powered airguns ever made. I got mine in 1976 and it cost me $189.Money well spent and the enjoyment I have derived from this gun is incalculable.

My Previous house in East Ventura was INFESTED with Mocking Birds. They were in every tree and bush and as soon as you shot one another would fly across the Freeway from the County Govt Center and take their place. I shot 6 the day we moved in and in the 15 years we lived there that gun accounted for easily 500 of these insidious creatures. Shots were either 10 or 40 yards. Ventura County actually still has a .05 cent Bounty on them as they are without a doubt the most annoying creatures ever invented. I was going to take a shopping bag full of them over to the Sheriff's office and collect but thought better.

We have nice Blue Jays at our home now and Mocking Birds seldom show up.

Randy

[jcwit]

If your piston is slamming into the front of the air chamber you have a problem bigger than reverse recoil.

Yes there is reverse recoil, but it is caused by the sudden stop of the piston and the piston should never slam into the front of the air chamber. Course who knows with todays ultra light zinc pellets.

[W.R.Buchanan]

The Piston is stopped by the front of the Air Cylinder That's the only way all of the compressed air would reach it's highest pressure,,, IE; highest compression= least amount of space left in combustion chamber.

If there was an unused portion of the cylinder in front of the piston the gun wouldn't achieve it's complete potential. All the air in front of the piston has to go out the hole in the end. Germans are very efficient, believe me virtually every bit of displacement is accounted for.

What do you think is stopping the piston at the end of it's travel? Obviously the piston seal is what is ultimately stopping it, but it is hooked directly to the front of the piston so it acts as a cushion.

If it was metal to metal, I'm afraid it wouldn't last long.

My HW35 has a Leather Seal, The R1 has a Synthetic one.

Randy

[jcwit]

The piston is at the end of it's travel before the pellet leaves the barrel. Otherwise the gun will self destruct from the piston slamming into the end of the compression chamber.

This is one of the problems with using to light of a pellet. Don't believe me, call any of the manufactures.

[jcwit]

Why do you think it is wrong to dry fire a springer?

by B.B. Pelletier
Okay, Grasshopper, enough Wax on! Wax off! It’s time to use your skills.
If you’ve been following the discussions over the past month about accuracy, you should now have the tools to be a pretty good judge of the potential accuracy of an air rifle and the relative ease with which that accuracy comes — even before taking the first shot. We’ll confine today’s discussion to just spring-piston guns, since they’re the most difficult to shoot.
How a spring-piston airgun works
This is a review for many of you, but we have enough new readers that perhaps it’s good to go over the points of how the spring-piston gun works. What I’m about to say holds true for guns with gas springs as well as guns with coiled steel mainsprings. They all work the same when it comes to their operation.
When the sear releases the piston, the piston starts moving forward rapidly at 50-60 miles per hour or 73-88 f.p.s. Unless there’s something like an anti-recoil mechanism to prevent it, the gun starts moving in the opposite direction. Since the piston weighs but a fraction of the weight of the whole gun, the gun’s movement is very slight.
Within a few hundredths of an inch of the end of its travel, the piston has compressed the air in front of it as high as it will ever go…given the piston diameter and length of the piston stroke. Due to this compression, the temperature of the air has also increased to a very high point. The piston wants to slam into the end of the compression chamber, but the thin cushion of highly compressed air actually slows it down and can even stop it. The pellet in the breech is sealing the air in front of the piston, and it hasn’t started moving yet.
However, at some point — and that point changes with each pellet used, the pellet can no longer remain stationary. There’s too much force pushing on its tail and it begins to move down the bore. The piston can now go all the way forward and rest against the end of the compression chamber, or it may have done so already and rebounded off the air cushion and now needs to go forward again. Each different type of pellet will determine exactly how this relationship of movement plays out, which is why some pellets feel good when you shoot them and other pellets seem to make the gun buzz and vibrate and even make noises that you may never have heard before.
When the piston reaches the end of its travel, it stops suddenly. When that happens, it imparts a hammer blow to the airgun, sending it in the same direction the piston was traveling. This is the second recoil, and it’s much more noticeable. At this point in time, the pellet is probably between three and six inches down the barrel and the entire gun’s moving.
The movement is in several forms. First, there’s high-speed vibration running through all the parts of the gun. You can’t see this vibration, even on a high-speed camera, but you can feel it. This is the buzz that you feel from some guns, and it can be so sharp that it actually hurts to hold the stock against your cheek.
Next, there’s a lower-speed vibration that’s both larger and much slower. If you had a high-speed camera, you could actually see the various parts of the rifle moving. The pellet is still inside the barrel when this happens.
Finally, there’s the recoil in both directions. Both are visible on a high-speed camera; and the forward movement, assuming we’re talking about a conventional spring-piston setup, is by far the largest. The gun starts moving forward before the pellet leaves the muzzle, but completes the movement after the pellet has gone.
Which spring-piston guns will be accurate?
Simply stated, breakbarrel spring guns are the most difficult to control. They may be just as accurate as underlevers and sidelevers, but they’re almost always more sensitive to the movement of the gun when it fires. That’s not to say that sidelevers and underlevers are not sensitive; but in comparison to breakbarrels, they’re less sensitive.
Let’s stay with breakbarrels for now. The ones with the longest piston stroke have the longest period of time for movement. That includes the high-speed vibration, the low-speed vibration and the recoil in both directions. As a rule, long-stroke spring-piston guns are the most sensitive to hold, and long-stroke breakbarrels are the most sensitive of all.
Then there’s the weight of the piston to consider. A heavy piston causes more rearward recoil when it begins moving and more forward recoil when it comes to a stop. You tend to find heavier pistons in guns with more power.
Put this all together, and you know that a breakbarrel spring-piston rifle that has a long piston stroke and high power will probably be the most sensitive airgun, as far as hold goes. It may be potentially very accurate; yet also be so sensitive that unless the hold technique is perfect, it’ll spray pellets everywhere.
Listen to this!
When I was doing the testing that lead to my R1 book, I tested my .22-caliber Beeman R1 with the factory tune and then with four different custom tunes. One of the tunes — from Venom — increased the power of the 18 foot-pound rifle to 23 foot-pounds, but it also removed nearly all vibration. It was by far the smoothest tune for that rifle. As a result, the rifle became easier to hold and shoot.
I then destroyed all of the mainsprings used in the testing by leaving the rifle cocked for a month with each of them, so the Venomac Mag-80 LazaGlide tune went away. While I had it and used it, I learned that it’s the vibration and not the power of a gun that determines how difficult it is to hold.
That tells us that if the gun is powerful without vibrating, it can be easier to shoot. You might think that a gas spring would give you exactly that, but they don’t always do so. The more powerful gas springs, while smoother than most steel springs of equal power, still vibrate a lot and require compensation with the hold.
What do we know?
If you believe what I’ve said to this point, then you know what it takes for a breakbarrel spring-piston air rifle to be the least sensitive to hold. It must have the following:

• Low vibration
• Short stroke
• Low recoil

Put all of that together and you’ll have a lower-powered, spring-piston rifle. Time for a short story.
Several years ago, I tested a Mendoza breakbarrel called the Bronco, oddly enough, that was very low powered. It had a strange-looking Euro-styled stock with a too-short pull (about 10 inches) and a hideous kidney-shaped cutout in the center of the butt. The stock was firewood, but the action was good. No, it was better than good. It was great!
The gun cocked easily, had a very short piston stroke, a wonderful crisp trigger and an accurate barrel. I proposed to Pyramyd Air that we have this rifle restocked with a western-style stock, like the old Beeman C1 carbine. They agreed, so I found the stockmaker and had the job done.
We then sent the newly-stocked rifle to Mendoza and asked them to create a model that had a similar stock, though with a pull suited to older youth as well as adults and a couple other important changes. Voila! The Air Venturi Bronco that you all know was born. You can call me an airgun designer if you like, but what I really am is someone who knows what it takes to make the right kind of airgun. Mendoza was already making most of it, but they needed prompting to change those few important details that turned their oddball Bronco, which wasn’t selling, into our Bronco, which is now a best-buy. It’s the same gun, with just a few important things changed. Think of it as the Jeep with the V6 engine that everybody loves, as opposed to the same Jeep with the underpowered 4-cylinder powerplant that someone buys because, on paper, it gets two miles per gallon better mileage. In real life, the details matter.
The Bronco is very insensitive to hold for a breakbarrel and as a result, deadly accurate in the hands of almost everybody. Contrast that with the guy who has to have the absolute last foot-second of velocity, so he buys the air rifle that’s guaranteed to make his life miserable — hard to cock, violent when shot and requiring the skill of a concert airgunner to shoot well. He may have some bragging rights; but at the end of the day, the Bronco owner will shoot a lot more and have more fun doing it.
There are many more stories, but I think my point has been made. You now know how to select a spring-piston breakbarrel that will be the least hold sensitive when shot. Now you know why I went bonkers over the Crosman TitanGP (Lower Velocity) that’s a really fine shooter.
On to other springers
Let’s talk about the underlevers and sidelevers. Within these, there are the underlevers that use a sliding compression chamber, like theBeeman HW97K, and those that have a loading tap, such as theHakim (made by Anschutz). There are sidelevers with loading taps, as well, but they’re not common. Sidelevers usually have sliding compression chambers, like the RWS Diana 48.
For whatever reason, both underlevers and sidelevers are less sensitive to hold than breakbarrels. Of these, the taploaders seem to be the least sensitive of all, though the TX200 Mark III from Air Arms has a sliding compression cylinder and is also very insensitive to hold.
The hold sensitivity for both underlevers and sidelevers does increase as the stroke length and vibration increase. Notice that I didn’t say anything about the power. The TX200 Mark III is very powerful, yet still very smooth and insensitive to hold. I would describe it as having a shorter piston stroke.
The RWS Diana 460 Magnum, in contrast, has a very long piston stroke and does need a lot of hold technique to shoot its best. The RWS Diana model 48 sidelever has a shorter stroke than the 460 Magnum and is also less sensitive to hold.
It seems that the same things that drive the hold sensitivity for breakbarrels also affect underlevers and sidelever guns. It’s just that these types of airguns start out with an advantage over breakbarrels in the sensitivity to hold.
What does that leave?
I have not discussed any of the other types of spring guns, such as the overlevers (they act just like underlevers) or those that cock via a lever that works in a different way, like the Haenel 310 and the VZ 35. All of these airguns are low-powered enough that they have good characteristics to begin with; as a result, they don’t cause any of the hold problems we’ve discussed.
Other issues
To this point, I’ve said nothing about the quality of the barrel, the breech lockup, or the overall fit and finish of the working parts of the powerplant. These items do affect the performance of an airgun and will break your heart if they’re not taken into account. Some air rifle barrels, for instance, look like 40 miles of rough road and will never deliver pinpoint accuracy no matter what’s done to the rest of the gun. Some barrels are crooked from the factory and can never be fully straightened. You can put lipstick on the pig, but that won’t change its manners!
The bottom line
What all of this means is that no one has to go into the airgun selection process blind. If you can determine the three important characteristics I’ve discussed here — vibration, piston stroke and recoil — you can generally know how difficult it will be to shoot each airgun well.
If you want to hunt with your new rifle, then by all means pick one that has plenty of power. But choose it to use it! Now that you’ve been informed, don’t buy a mega-magnum spring rifle, then whine that it’s too difficult to cock or too hard to shoot accurately.
Many of the veteran readers on this blog seem to keep harping on the low-powered springers for a reason. Guys like Kevin and others keep going back to rifles like the Beeman R7 and the HW50S because they know what wonderful shooters they are. Don’t kid yourself that these guys are not experienced with the powerful springers, too. Most of them have tried the big guns and found they didn’t enjoy all that it took to make them do their jobs.
There’s a place for the RWS Diana 350 Magnum and the Walther Talon Magnum, but some thought has to be given before purchasing either of them or any other spring-piston air rifle of equivalent power. Both rifles are built for a specific purpose, which is hunting. They’re hard to cock and take a lot of technique to shoot to their potential. Neither rifle is the best choice for a first airgun for someone who is either new to airguns or new to shooting altogether.
I hope this report helps some of our newer readers narrow their selections of possible air rifles to purchase next. As always, there will be exceptions to what I have said, but they only serve to prove the general rule.

[jcwit]

Note the 3rd paragraph under the 1st red heading in the above post.

[W.R.Buchanan]

This was a very informative article. And I indeed did neglect to include the small volume of air at the end that acts as a cushion to stop the piston from actually hitting the end of the cylinder,,,and that is why we don't dry fire the guns.

However if you dry fire the gun, the piston does in fact hit the end of the cylinder,,, right?

Randy

[jcwit]

Correct, and that is another reason not to use those real light pellets in the high power springers and air ram guns.

[too many things]

I bought a Gamo hunter. and a good set of steel weaver mounts. about 5 firings and the scope would move 1/2 in
Prymide sent me a set that has a set screw in the middle of each base. there was a drill bit that came with the set.
you got the scope where you wanted it. for eye relief . Then removed the scope from the gun and drilled in the base hole.
the bit was made with a stop so it just put a dimple in the top of the receiver. then you used the set screw to go in the base hole.

I never had the scope to move again. The bases were about $50 but it worked.
I did find out one thing very fast, you cant use the old flat Crossman pellets. Just blew a hole and had to take a cleaning rod>{I didn't have at the time} to get the base of the pellet out

[Southerngunner]

Years ago before I knew better I installed an old weaver 1.5x4 that I had on a Marlin 444 levergun . I put it on a Beeman R-9 spring piston rifle and within a dozen shots the scope had destroyed itself. The dealer that sold me the Beeman said that normal big game scopes were usually not rated for the negative recoil from a spring piston rifle. Since then any Air rifle that I purchased had a scope specifically made for Air guns only.

[LtFrankDrebbin]

jcwit,
Thanks for that article. Very good! It should be a sticky on it's own in the airgun section.

Smoother is better? Oh yeah, My T01 34 was good as a polished and de-burred standard. Now it's brilliant with the Vortek sub 12ftlb kit in there. 11ftlbs with 8gr pellets=one sweet shooter. We have a lot to learn from the UK guys. Pellet placement with sub 12ftlbs will get results!

[LAKEMASTER]

i have a bushnell banner 3x9x40 on my cheapo crossman storm.doesnt loose 0 until i change pellets

[LAKEMASTER]

i will be honest though, i didnt know there were actual air gun scopes... so i may not know if ive been doing wrong all this timelol

[Black Beard]

Extract from a currrently unpublished work. Designed to be read with a graph but I don't know how to do pictures on the forum:


A Typical Modelled Air Gun
The following is based on a modelled HW80 (12ftlb R1) and gives a millisecond by millisecond explanation on what is going on. This same model will be used later in the book to illustrate the effects of changing different internals so it is probably worth going through this.
Starting at the point the trigger is pulled, the piston is released and the spring exerts a step force on the piston, accelerating it. The piston moves forward and by T=7ms the force from the spring and the air inside the cylinder have equalised. The piston starts to decelerate until t=9.4 seconds where it changes direction and starts going backwards.
Meanwhile, at T=8.3 seconds the pellet starts to move. The pellet accelerates with acceleration roughly proportional to the barrel pressure (less friction, pressure head losses because of the velocity of the pellet and losses from the air pressure in front of the pellet).
The cylinder pressure continues to increase until T= 9.3 ms. There is a reasonable pressure loss across the transfer port as large amounts of air flow from the cylinder to the barrel. In this case the flow does not choke. Peak barrel pressure happens slightly before peak cylinder pressure as the pellet is moving down the barrel- increasing the volume of the space behind the pellet and dropping barrel pressure. If the transfer port was larger then the pressure loss would be less and more air would be pushed through in to the barrel.
The piston stops moving at about T=9,4 seconds and then starts going backwards. The closest it comes to the cylinder face is (data not checked yet, about 1.5mm though). In air guns it is normal that the peak pressure happens a little before the piston stops moving and starts going backwards.
At T=9.8 seconds the barrel and cylinder pressures more or less equalise. At this point the quantities of air moving across the transfer port are small. This continues until the pellet exits the barrel at 11ms. The pressure will drop as the piston and pellet move in opposite directions and the overall volume of the system increases. Small quantities of air will flow across the transfer port. In this case, the pellet is heavy enough compared to the piston that the piston the % rate of increase in volume in front of the piston is larger than the % rate of increase in volume behind the pellet. The pressure in the cylinder drops faster so it sucks a small amount of air back between T=10.2 and the pellet exit.
As the pellet goes down the barrel the pressure on it drops and its acceleration reduces. Its velocity starts to level off. At the same time the piston is being accelerated backwards. The pressure is dropping on the piston to and the spring is slowing it down. The piston reaches a peak velocity of almost half the peak velocity in the forward direction when the pellet exits at T=11ms.
At T=11ms the pellet exits. The air in the barrel is blasted out behind the pellet and the barrel pressure drops. At this point, the pellet is outside the model and should be ignored- use a ballistics programme like Chairgun to see what happens to it. Air flows rapidly across the transfer port from the cylinder and in to the barrel. This flow rate peaks at about a tenth of the highest rate that was seen on the forward stroke. This flow continues to T=15.2 seconds.
The piston continues to move backwards against the spring but it is decelerating against the spring and the pressure in the cylinder is decreasing. At T=15.2 seconds the combination of the air being lost across the transfer port (and down the barrel and to the outside air) and the increasing volume in the cylinder mean that the pressure in the cylinder is less than the external pressure. At this point the air flow reverses and the cylinder sucks in air from the barrel.
At T=18.2 seconds the piston has stopped and has reached its peak displacement backwards, of about 40% 0f the original stroke length. It then starts moving forwards again. It continues to suck in air through the transfer port until T=19.8 seconds.
The piston continues to accelerate forwards just as it did for the initial forward stroke (of T=0 to T=9.3 seconds) but there is no pellet in the system to stop air from being pushed out of the barrel. The air pressure in the cylinder increases as the piston compresses the air in front of it and the flow goes forwards. The drag in the transfer port resists the air flow across it (which will choke) and the pressure in the cylinder builds up. This pressure resists the movement of the piston and slows it down between T=24 and T=27 seconds. Unfortunately, it doesn’t slow it down enough and the piston strikes the end of the cylinder and stops.
The drag in the cylinder-barrel system increases significantly as the piston comes close to the cylinder face which is why there is a drop in the flow rate. After T=27 seconds the remaining gas in the cylinder gives the piston another push backwards and it does another small cycle between T=27 and T=34 seconds.
There are several things worth noting about this cycle:
· The pellet starts moving forwards when the piston is moving forwards on the initial stroke.
· The piston moves back a long way on the backward stroke
· The transfer port has a big impact on how closely the cylinder and barrel peak pressures match.
· Air flows in both directions, depending upon the weight of the piston and pellet and whether there is still a pellet in the barrel
· Between T=11 and T=24 seconds the piston velocity appears wavy. This is because the HW80 has a heavy spring with a low preload. The spring is bouncing about inside the air gun when the piston is forwards.
· The transfer port has a big impact on how effective the cushion of air slows down the piston at the second forward stroke.

So what does this all mean?

The bit that smashes your scope is the final impact of the piston. This is mostly controlled by the relationship between the cylinder capacity, the transfer port diameter and the energy that the piston gets on the push backwards. Small capacity, large transfer port, excessive spring and heavy pellet will give big impacts and break your scope. Far too much spring and preload will make the piston crash in to the end of the cylinder on the first forward stroke. This is pretty much the same thing (and it will do it another push back and crash to, so the scope gets 2 large shocks).

BB

[Ithaca Gunner]

Well, in an earlier post I said I would probably get a Hawke scope for my Hatsan 95 Vortex, and I meant to. Did some comparing on Pyramid Air and went with another UTG, 3X9. Same price as the Hawke 3X9 I was looking at, but with a bit more eye relief. Springer rated, fully adjustable objective lens, sighted it in today and it did very well on the Hatsan. Now I see I should adjust the trigger to take full advantage of this scope. $79.95, not bad at all.

[bottomline]

I have an RWS Night Pro 3-9x44 (about $90 i think) on my RWS Diana Panther.

[Doggonekid]

I must be the only Leupold nut out here. My two scopes are both Leupold EFR scopes rated for air rifles. I have always said spend as much on your scope as you do on your gun. With air rifles cost blasted past $700 for a good PCP now days I go with Leupold. Never had any trouble with springers (Beeman R1) to PCP (Air Arms S410).