RWS Diana model 45 – Part 2
by B.B. Pelletier
Photos and testing by Earl “Mac” McDonald
Mac’s RWS Diana 45 is a real classic from the days of the great horsepower races. It was at one time one of four different models that could sometimes deliver velocities in excess of 800 f.p.s. in .177 caliber.
This vintage breakbarrel is well-known to many of you readers. Apparently, the most common find is a 45 that’s lost most of its finish but still shoots great. And, the loss of finish comes from handling most of the time, so it would appear that the RWS Diana 45 is a gun that people like to shoot.
The 45 was one of the very first Dianas with a modern scope rail attached to the top of the spring tube. Earlier guns, such as the model 27, had a ramp in the same place, but it was designed to accept only aperture sights. There would still be some more slight design changes to come, but the 45 scope rail was essentially the final product.
The RWS Diana scope rail looks a lot like the rail found on later Diana spring guns. Only the big-headed screw is missing from this early attempt.
The importance of the scope rail is that today’s UTG scope base for RWS Diana airguns will fit. I would suggest getting the model designed for the sidelever rifles instead of the breakbarrels.
The cocking link is a single link rather than a two-piece, articulated assembly. For that reason, the cocking slot in the forearm has to be longer to allow clearance for the link to do its job. And, a lengthy cocking slot often allows excess powerplant vibrations to be generated.
The one-piece cocking link demands a longer cocking slot in the forearm for the action to cock.
The one-piece cocking link has one additional aspect. It doesn’t allow the barrel to go backwards as far as a two-piece, articulated cocking link does. Consequently, the rifle with a one-piece link will have less swept volume than a similar rifle with a two-piece link. Call it what you will, that is the hallmark of the modern magnum springer.
Two rifles’ cocking linkages in direct comparison. The RWS Diana 34 (the bottom rifle) with the synthetic stock allows the barrel to come back much further during cocking, because the cocking slot in the stock is twice the length of the one in the 45. That means the piston stroke is longer, which means that the smaller, lighter rifle is also the most powerful. An articulated, two-piece cocking link is the only other way to increase the cocking length.
And now for the velocity
The first pellet Mac tested was the RWS Superdome, which weighs 14.5 grains in .22 caliber. In the test rifle, they averaged 648 f.p.s., with a 10 foot-second spread that ranged from 643 to 653 f.p.s. The average muzzle energy was 13.52 foot-pounds.
Next, he tested JSB Exact Jumbos. At 18.1 grains, these heavy domes averaged 603 f.p.s. with a 14 foot-second spread that ranged from 597 to 611 f.p.s. The average muzzle energy was 14.62 foot-pounds.
This next result is going to drive some of you crazy. Mac tested 14.3-grain JSB Exact Express pellets and obtained an average velocity of 609 f.p.s. That’s right, they shot only 6 f.p.s. faster than the heavy Jumbos. This unexpected result has to do with the fit of the pellet to the bore. These pellets had an extreme velocity spread of 16 f.p.s., ranging from 598 to 614 f.p.s. And, they produced only 11.78 foot-pounds of muzzle energy.
Then, Mac tested the rifle with H&N Diabolo Sport wadcutters. This is a 13.73-grain pellet, so it’s leaning to the light side of the spectrum. They averaged 680 f.p.s. with a 23 foot-second spread that went from 671 to 694 f.p.s. The average muzzle energy was 14.07 foot-pounds.
Not wanting to exclude the Crosman Premier line, Mac next sampled 10 of those 14.3-grain pellets. They averaged 637 f.p.s. with a 29 foot-second spread. The low was 630 and the high was 659 f.p.s. The average muzzle energy was 12.89 foot-pounds.
The last pellet Mac tested was the new RWS HyperMAX lead-free pellet, which in .22 caliber weighs 9.9 grains. You would expect them to scream at that weight, and they did. They averaged 789 f.p.s. with a 14 foot-second spread that ranged from 780 to 794 f.p.s. The average muzzle energy was 13.69 foot-pounds.
Mac noted that all the pellets in this test were too small for the rifle’s bore. The HyperMAX pellets were small enough to enter the muzzle, even though the barrel is choked! That would explain the disparate numbers we’re seeing here.
Next, we’ll test the accuracy of this vintage rifle.