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Air Rifle Scope Mounting Basics

Scope Mounting Basics

Your brand-new airgun just arrived, and you are eager to try it out. You also purchased a air rifle scope (make sure it's airgun rated if you plan to install on a springer) and the recommended mounts and rings that fit, and all you need to do now to enjoy your new acquisition is to install the scope on the gun. So go ahead…..install the scope and get shooting!

What do you mean you’ve never put a scope on a gun before? Really? Oh….okay. Well, it isn’t hard, so let’s just walk through it together.

Airguns come in many shapes and sizes, and different manufacturers use different mounting systems. As a general rule, you will most likely find 3/8" (11 mm) dovetail grooves machined into the top of the receiver on the majority of airguns. However, some manufacturers use a different system that installs a rail on top of the receiver. Be sure to check the width of the rail so you can order the proper-sized mounts. If you come from the firearm world, and are used to Weaver-style mounts, there are adaptors that convert from dovetail to Weaver, allowing you to use mounts you already possess.

Now consider the air rifle you have purchased. Is it a heavy-recoiling springer? If so, you will want to take advantage of the scope stop that hopefully came with the gun. Often, you will find scope stop holes already provided by the manufacturer on top of the receiver between the dovetails. If the scope mounts you purchased have a scope stop pin, the pin goes in the hole to prevent the entire mount and scope from creeping back on you when shooting. If there are no holes provided, then you can install a scope stop near the rear of the dovetail that will provide that function for you. A one-piece mount is often a good investment if you have a heavy-recoiling airgun, in that it provides a longer gripping surface than a two-piece mount. They aren’t quite as flexible as a two-piece mount, but they are very stable, and lessen the need for a scope stop. If your airgun is a lower-recoiling type, either a low-powered springer or a PCP/CO2-powered gun, a scope stop is rarely called for as the recoil isn’t enough to cause your scope to creep.

Taking the top of the rings off the scope mount, place the mount or mounts on the gun and fasten them to the gun. Don’t bear down on the fastening screws yet, as you may need to make some adjustments.

Place your scope in the rings, making adjustments for a good fit, and place the top half of the rings on the mount.

Fasten the top of the rings just enough to hold the air rifle scope in place, yet allowing you to still be able to turn and slide the scope forward and back. Now position the scope so that the eye-relief is to your liking, perhaps 2” to 4”. (Eye-relief is the distance from your eye to the rear of the scope, the part that you are looking through). Once the correct distance is obtained, rotate the scope in the rings so that the scope is level in the rings. The vertical reticle in the scope needs to divide the gun in half when you look through it. Now that you have the correct eye-relief adjusted, and your scope is mounted evenly in the rings, fasten the rings down on the scope by alternately tightening the screws. On a four-screw ring mount, I normally do two on the front (diagonally positioned from each other), then two in the back. I then fasten down the others, alternating from front to back. It’s sort of like changing a flat-tire….you tighten the lug nuts alternately, not the ones next to each other.

Be careful that you don’t bear down too hard on the ring screws….you can damage the tube of your scope, which certainly isn’t your intention. After the rings are tightened down, go back and tighten the entire mount to the gun.

There is an issue that affects your scope-mounting procedures. It is called barrel droop, seen mostly in break-barrel designs. Since the open sights on an air rifle are on the barrel, shooting with open iron sights will not affect your point of aim. However, when you place a scope on the gun, the scope is mounted on the receiver, not the barrel. To compensate for the barrel droop found in some airguns, you must sometimes shim the scope in the rear mount to more closely align the scope with the barrel. There are different materials you can use, from tape to strips of aluminum cut from a drink can. However, to avoid having to shim the scope, an adjustable mount can be purchased that will allow you to make adjustments to the mount itself in order to compensate for barrel droop. The RWS C-Mount is a terrific mount. It is fully adjustable for windage and elevation and makes sighting in a scoped air rifle a breeze. You might think that you can just sight your scope in with the adjustments on the scope itself but sometimes the barrel droop is too severe for this and the scope will not have enough adjustments to get you on target. RWS air rifles are know for this and, therefore, the RWS C Mount is recommended for them.

Another option is to buy pre-compensated mounts that have a built in droop allowance already machined into the mount itself. It isn’t an adjustable mount, but the mount was purposefully machined with a slightly higher rear scope ring to allow the scopes normal adjustment knobs to be able to adjust enough within their normal working range to get you on target.

The following link will give you another visible demonstration of how to mount a scope, closely following the steps I outlined above.

http://www.arld1.com/images/swfs/scopemountingsetting.swf

Once you’ve mounted your scope, grab a piece of paper or cardboard, some pellets, and let’s go sight in your scope-mounted air rifle. Place the target about 10 yards away. Since we are so close to our target, protective eye wear would be a good thing to have in the event of a ricochet. Take a few shots at the center of the paper, seeking to just get on the page. Using the scope's horizontal adjustment knob, get the point of impact horizontally centered on the target. Once you’ve accomplished this, work on the vertical adjustment to bring the point of impact to about 1” or so below the point of aim.

Now move the target out to 30 yards away and shoot a group of 4 or 5 shots. Don’t worry about flyers that differ from the group at this point, concentrate on the group itself. At 30 yards, you should be close to dead on for most airguns. This will vary from gun to gun depending on the power of each gun. Don’t forget that if you shoot a different pellet than the one you used to sight in with, you will have a different point of impact due to the weight of the pellet and the fit of the pellet in the barrel. So sight in your gun with the pellet you intend to use. Mounting a scope isn’t hard, and the method described above will suit the vast majority of airgunners. There are more advanced methods for FT shooters and accuracy devotees that involve using a level, working up a chart to plot the impact point of each type of pellet, and adjustments to the scope for each shot that occurs at a different range. I’ve never used that method myself, finding the above method of scope mounting more than adequate for hunting and plinking.So now you’re ready to go shooting. Enjoy!

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Comments

Where do you find the rating of scopes. Because I want the Gamo Shadow which comes with the BSA 4x23mm air rifle scope with fixed objective and I was wondering if that is a good enough scope for a springer?

Garrett,
If the spring-piston gun you are buying from Gamo comes with the scope, then the scope should hold up on a springer. Gamo is the largest airgun company represented in the US, and the scopes they match up to their guns are rated for the guns they package them with.

just read the article on sighting in scopes very interesting mr curran [glasgow]

I tried to install the RWS C-Mount[one piece] without success. The dovetail would not anchor securly to my Diana 460 .22cal.[new]. I would like some advice on a good one piece scope mount for my Diana.

Stan,
Accushot makes a one-piece mount with a pin that should fit into the scope-stop holes found on the RWS 460. Airgun Depot carries the Accushot line, and that was the rail recommended to me by an owner of the 460.

I bought a cheap china red dot viewfinder and the mount is too wide for my airgun. Is there a conversion kit readily available?

William,
Both B-Square and RWS make an adapter that goes from the rail-type to the Weaver-style based mount. But I can't think of a conversion kit that might suit your needs off the top of my head.

You might take the reddot to a gun shop and have them determine the size of rail that particular reddot is made to fit. Then a search of several sites might yield you some results.

Randy

i have a .22 rifle i want to mount a scope it has no groves or screws to attach rings can you help

Jon,
What kind of rifle is it? Make and model would help.

My rws 350 with scope is shooting 6" to the right. Which way do I turn the scope screw CW or CCW?

The scope adjusting knobs should have an arrow with an L or an R on it. If you are shooting 6" to the right, then you need to turn the reticle in the left direction.

Sometimes scopes are backwards from how they are marked, so if that doesn't work, go the other direction. Either way, you've got a 50/50 chance of being right!

I bought a scope for a break barrel air rifle. My gun is a chinese that you you pull down a leaver to prime for firing. I mounted the scope and it shots low. I turned the height knob as for as I could to bring it up and it is still not enough. Do I shim the front ring or the back ring to bring it up.

thanks Tim

Tim,
You will need to shim the rear ring to bring the scope in better alignment with the barrel.

The vertical reticle in the scope needs to divide the gun in half when you look through it. ??
When I look through the mounted scope, (the scope was not mounted when I bought the gun) I do not see the Gun (Gamo Big Cat 1200).
The instructions that came with the Gun and scope show some graphics on how to basically adjust the scope, i.e : correct shoot, incorrect shot, but I can not see the barrel (barrel open or closed). Where am I going wrong?

Franz,

I suppose that comment is a bit misleading. What I meant was that you should be able to look through the scope from a further eye-relief than you would actually use when shooting, and see if the verticle reticle seems to bisect the gun's barrel/stock. Back your eye up from the reticle enough to see both the crosshairs and the gun underneath.

Randy

i have Diana 350 Magnum which has a very powerful recoil

every time i fix my scope and after 20 or 30 shots i have to fix the whole thing

I have some questions now
1- i need a mount base but i do not know what to buy

2- i found the RWS C Mount and i found UTG Mount base with 2P mounts and it was written on it "stops shifting forever!"
which one is better?

3- what is the difference between Leapers and UTG?

please help me!

Mohammad,
A good 1-piece mount like those featured here:

http://www.airgundepot.com/onepi11mdomo.html

These will help resolve the problem of your moving scope and mounts. The more screws you have on the mount to tighten, the better the grip it will have.

Hi,
I am from India. Normally I sit and drool whenever I visit your site and see all the beauties displayed there. Air Rifles are not allowed to be imported into India by Government law.

I have,therefore finally purchased an Indian made air rifle, with imported German mechanism. It is reasonably powerful.

Unfortunately this gun is devoid of rails etc at the rear end, where a scope mount could be fixed. Its just a round cylinder there. Can you please advise as to how may I fix a scope, which I am dying to do.

Thanks,

Atanu

Atanu,
If your gun has no scope rails at all, then your choices are very limited.

You can TRY to have the receiver drilled and tapped, but you may run into issues like interfering with the spring operation if the tap screws go too deep.

You can always solder an aftermarket rail onto the receiver. The trick here is to get the rail lined up correctly before fixing it into place.

Another option would be to mount a long eye-relief scope on the barrel itself, similar to how "scout" rifles are configured.

Last but not least, if you have access to a good gunsmith, you might have them see if they can cut you some dovetails into the receiver without doing any damage.

I have a Diana Mod 34 and recently purchased a Leapers 5-16x50mm scope. Problem is, the gun shot beautifully without a scope. After installing the scope with a single piece 3-set screw mount, I can't sight in the gun. I get it sighted close then all of a sudden everything is off. I've spent a few hours and this occurs over and over again. Right now, gun is far more accurate without a scope.

Devin,
Here are some things to check.....is the one-piece mount moving along the rail? You should be able to see some marks where it is slipping slightly with each shot if it is moving on you.

Second, are your rings secured snugly, keeping the scope from moving within the rings?

Third, check out the scope itself....there is a possibility that the reticle has broken loose inside the scope.

Check each of those areas first, and you may go so far as to mount the scope on a different gun and see if you can repeat the problem.

Randy

tengo un rifle diana 35 5.5 balines y se rompio la mira de referencia que trae de fabrica, quisiera comprarla ¿ que debo hacer? aqui en maracaibo no se consigue

I just read the instructions for mounting a scope on an air rifle. I have the new Crosman NPSS Nitro break barrel. Do I need to put a shim under the scope to compensate for barrel droop? I'm totally new to airguns/scopes, thanks a lot!

Ricardo, El traductor en línea para su pregunta no me dio una traducción muy buena. Pienso que usted quiso comprar una vista para su .22 airgun del calibre, pero I' m no sure cuál usted está pidiendo alrededor.

Syd,
I did not need a shim for my NPSS. I would try mounting the scope and doing some adjusting before resorting to shimming your scope. There appears to be a minimum of barrel droop on the NPSS that I have.

Give it a try first, and if it doesn't suit your needs, consider slight shimming or changing your mounts.

Randy

Hi William,
If this is your first spring-piston airgun, be aware that they are different animals than any other type of rifle.

You need to hold the rifle as gently as possible, just enough to keep it from falling out of your arms.

Rest the forearm on a soft surface such as your outstretched palm, but avoid hard surfaces. The recoil of a spring piston gun makes it move oddly compared to other rifles.

Next, try moving your point of rest (on the forearm) to different locations until you find the best location for accuracy.

Also, try several different kinds of pellets. Like people, the air rifle will have its favorite ammo, and others just don't shoot as well as the preferred ammo.

Last, make sure the scope is undamaged, and that the scope mounts are creeping on you with each shot. Spring piston air guns are notorious for breaking scopes, and moving the scope mounts around, as well.

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