Diana 45
A late Diana 45 from RWS.

Part 1

History of airguns

This report covers:

  • Removed the stock
  • Trigger 1
  • RWS Hobbys
  • RWS Superdome
  • Trigger 2
  • Cocking effort
  • Discussion
  • Front sight
  • Summary

Today we look at the power and velocity of the new/old .177-caliber Diana 45 that I got last year at the Malvern, Arkansas airgun show. And I think the absolute first question we have to answer is — has this rifle ever been tuned? I believe that it has.

Removed the stock

So I took off the stock to get a better look at the mainspring, because if it has been tuned that’s where it will show. And to my eyes, it has. The mainspring is coated evenly with a light grease that doesn’t look like moly and it also doesn’t look like Diana put it there.

Diana 45 mainspring
The Diana 45 mainspring looks like it has been out of the gun and greased.

I wiped off some of the grease to examine it closer and it didn’t appear to be moly. It seems to be regular light machine grease.

Diana 45 mainspring
I wiped some grease off the mainspring and it did not look like moly.

Trigger 1

As long as the action was out of the stock I took the time to examine the trigger and to adjust it lighter. There is just one adjustment screw that can be turned, but a second screw is heavily lacquered to prevent adjustment.

Diana 45 trigger
The trigger has one adjustment screw (left arrow) and another that is lacquered in place so it can’t be adjusted (right arrow).

I have more to say about the trigger in a bit, but for now, let’s move on.

The rifle went back together and I started testing it. I had oiled the leather piston seal with 8 drops of Crosman Pellgunoil the day before. I dropped it down the barrel with the rifle standing on its butt. This was 16 hours later, so I figured the oil had run down the barrel, through the transfer port and soaked into the leather piston seal.

RWS Hobbys

I discounted the first several shots to let the oil settle down. After that 10 RWS Hobby pellets gave an average velocity of  681 f.p.s. That’s a bit low for a 45. The last 45 I tuned gave an average of 858 f.p.s. with Hobbys with a 24 f.p.s. spread. The spread for this rifle went from a low of 669 to a high of 699 f.p.s. — a difference of 30 f.p.s. At the average velocity this pellet generated 7.21 foot-pounds of energy at the muzzle.

A Hobby should go out at over 800 f.p.s from a 45 in good condition. I may have to open her up after all. I will say this though. The rifle does not buzz like 45s are prone to do. So I may shoot the rest of the test with things the way they are.

RWS Superdome

The 45 put 10 RWS Superdomes out at an average 604 f.p.s. The low was 597 and the high was 608, so the spread was 11 f.p.s. — a lot tighter than the Hobbys. At the average velocity the 8.3-grain Superdome generates 6.73 foot-pounds of energy.

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H&N Baracudas

The last pellet I tested was the 10.65-grain H&N Baracuda. Ten of them averaged 521 f.p.s. with a low of 512 and a high of 531 f.p.s. That’s a difference of 19 f.p.s. At the average velocity the Baracuda generates 6.39 foot-pounds of energy.

Trigger 2

On shot number 25 — the fifth in this final string I felt stage two of the trigger for the first time. I was set to tell you this trigger is a single stage until that happened. But it is two-stage and the letoff is crisp and delightful. Stage one is 1 pound 10 ounces and stage two is exactly 2 pounds. I like it.

Cocking effort

This rifle takes 39 pounds to cock. That’s way too much for the power output. Something has to be done.


The rifle is smooth, but not performing at its best. The trigger is about as nice as a sporting trigger gets. Im hoping the accuracy will be also.

Front sight

Reader Mike Melick from Flying Dragon Air Rifles was kind enough to gift me a Chinese copy of a front sight, so my 45 now has open sights front and rear. Naturally I have to test it that way. Yes, it accepts inserts.

Diana 45 front sight l;ef
The front sight has two screws to tighten it to the dovetails on the barrel.

Diana 45 front sight right
Each sight base screw has a nut on the opposite side.


What we have discovered is this Diana 45 is underperforming and cocks with too much effort. It fires relatively smooth and the trigger is now delightful. If the rifle is accurate as well, this should be a good test.