by B.B. Pelletier

Part 1
Part 2

Today, I’ll tell you how the new Leapers scope base for RWS Diana rifles installs, and give you some insight into what it was like to test this thing. The first thing you need to remember is that every RWS Diana air rifle has a different amount of droop. In general, the break barrels have more than the fixed barrels. I was fortunate to have on loan from Pyramyd Air an RWS Diana 34 Panther with a huge amount of droop. So much, in fact, that it was impossible to get on target at 20 yards by using just the scope’s internal adjustments. That was exactly the kind of rifle I needed to test this new base, because that was the worst problem of all…not a gun with a few inches of droop, but one with almost 21 inches at the most useful airgun range of 20 yards. If a base could compensate for a rifle like this one, it would work for most of the others that have less droop!

To put this into perspective, let’s look at a target I shot with the scope adjusted as high as it would go.


A 20-yard target shot with an RWS Diana 34 Panther and five 7.9-grain Crosman Premiers. The Leapers scope is adjusted as high as it will go. The aimpoint is the center of the top bullseye (this target was hung upside-down in the pellet trap). The pellets impacted over 7-1/2″ below. If you tried to shim the scope to compensate for this amount of droop, you’d have to use so much shim material in back that the scope tube would be at real risk of bending when the ring caps were tightened. Until now, the only solutions for this were either adjustable rings or a special droop scope mount.

Don’t think that just because the target shows a 7-1/2″ drop that the rifle droops only that much. The scope was adjusted AS HIGH AS IT WOULD GO! If I centered the reticle, the pellet would be almost 21″ below the aimpoint.

The amount of droop was so great that the engineer at Leapers could hardly believe me. Anyone who has not actually experienced this before would find it hard to believe, but this is one of the reasons I wanted this new base so much. Over the years, I’ve had to talk many shooters through the workaround of scope shimming or convince them that adjustable mounts were what they needed. They always asked me how an airgun company could make a product with this much droop and not have something to correct it. To answer them I will point to the Hubble Space Telescope, which had vision problems for many years until corrected in orbit by NASA. If a telescope costing two billion dollars can have vision problems, I guess an air rifle can have barrel angle issues. Besides, Diana isn’t alone in this situation. Many other breakbarrels and some fixed barrels have a droop problem. It’s just that many more RWS Diana rifles are in use around the world and they all seem to droop in varying amounts but similar in that they all have it.

Speaking of fixed barrels, I did test a second RWS Diana rifle during the base development. I tested a .22-caliber RWS Diana 460 Magnum, which is a powerful underlever rifle. That rifle didn’t droop as much as the breakbarrel 34, but it still drooped more than some scopes can compensate. Other scopes would just be able to get on target with all their vertical adjustment used up. Although the one new mount would have worked for this rifle, Leapers decided to make a second base with less droop built in. They call it their 460 base. That gives you a choice of slope angles to fit any rifle out there.

We finally got it right
In part 2, I told you about all the prototyping Leapers did. I’ve left out the valuable lessons we learned in this testing because Leapers spent a great deal of their own money to get this product right. Others who try to copy them will probably run into the same problems we did and have to figure how to solve them.

By the fourth prototype, Leapers got the design and the slope right. All I had to do was mount the base, attach two rings and slap in a scope. The new base ended up with the vertical adjustment of the scope between the midpoint and the three-quarters point when the pellets were landing on target at 20 yards. That means the gun can be shot out to a great distance by using the internal scope adjustments because the base preserves most of their adjustment range.


The recoil shock shoulder hangs down in front of the new base to contact the front of the rifle’s base. After that, no movement is possible.


At the back of the new base, a relief cut prevents the base from touching the big-headed screw on the back of the rifle’s scope base. See that deep hole in front of the relief cut? That is a vertical scope stop screw for those who want to use it. It isn’t necessary, but Leapers put it there because they know some people will want to use it.

Watch the video, if you can
The RWS Diana rifles have gone from being the most difficult rifles to scope to the easiest because of this new base. Paul Capello made a short video that shows how easy it is to now mount a scope. That video is on both the video page and on the product page with the new bases. Since some of you can’t watch videos, I’ll show you how to mount a scope using this new base. I will use the 34 Panther for my description and photos, but the procedure is exactly the same on all RWS Diana rifles and for either new base.

Installation
Loosen the screws on the sideplate of the Leapers base and slip it into the dovetails of the base on the rifle. Slide it back until the recoil shock shoulder contacts the front of the rifle’s base. It won’t move any farther. Snug it down. The base is installed. Time: about a minute, working slowly.


The RWS rifle’s base has 11mm dovetails to accept the Leapers base.


Leapers’ new base simply clamps on the rifle’s base. The recoil shock shoulder rests against the front of the rifle base. Now, the airgunner is presented with numerous slots to which Weaver rings will attach.


All Weaver rings have a 3.7mm-wide key across their bottom. It fits into one of the slots in the Leapers base. The Leapers base is cut with 5mm Picatinny slots, but don’t despair – hundreds of thousands of centerfire rifles also use a Picatinny base with Weaver rings. Just slide the ring to the rear of the slot before fastening.

Next, install two Weaver rings in the slots of the Leapers base. Position them far enough apart for the scope you’re using and back far enough for good eye-relief when holding the rifle. Time: about two minutes, working slowly.

It’s best to use scope rings with four cap screws on all RWS Diana guns, so the caps are wide enough to provide maximum clamping pressure on the scope. Medium-height rings will be high enough for all scopes, because the Leapers base also raises the scope. Low rings will work with many scopes.


Attach two Weaver rings to the base. Separate them as far as the scope tube requires, and don’t forget to check the scope’s eye relief.

Last, install the scope in the normal fashion, using the instructions I provide in the scope-mounting article. Time: about 10 minutes, working slowly.


Lay the scope on the rings and fasten the top straps.

You’re done!
The new base takes care of two things:

  1. The barrel droop is corrected by the slope built into the base. Your scope will be on paper during sight-in and not too far from where it needs to be.
  2. The new base puts an end to scope base and ring movement. The recoil shock shoulder cannot be budged and the base slots and Weaver keys form a positive locking system for the rings.

If you’d like to print out directions, Leapers has a step-by-step sheet that is linked to both scope mount bases in the left column on the product page (under “Manual”).

The last report
This new base puts an end to barrel droop and all the problems associated with scope creep (broken big screw heads and narrow scope stop pins gouging scope bases on the rifle). It cuts the scope mounting time by two-thirds, and takes the operation from trial-and-error to plug-and-play. Now we can put our time to more profitable enterprises.