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Education / Training Diana 45: Part 2

Diana 45: Part 2

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.

Hunting Guide

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.

author avatar
Tom Gaylord (B.B. Pelletier)
Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

37 thoughts on “Diana 45: Part 2”

  1. BB,

    I’m suspecting this rifle is oversprung and you will have to decrease the amount of preload. Seems like the weeks required to understand the trigger was cut down by the fact that the manufacturer prominently secured the second screw from being adjusted.


  2. BB,

    Since the trigger is so nice, I don’t expect that you’ll be monkeying with it, but could you address what you suspect the two screws WOULD adjust, if you had a mind to fiddle with them. My Model 45 hasn’t been fired for many years and I thought I might do some testing along with you just for comparison. Mine is a 1984 (I think) and I bought it new and know that it is still factory original. When you reminded us in Part 1 that the seal is leather I was thinking that petroleum based Pellgunoil would not be the best oil to use to recondition it. I thought that because of the high compression that it could damage the seal. Obviously I was wrong, but would silicone oil work as well? I think I may also use that LPS brand Red & Redi aerosol grease that we discussed in another report to see how it does on the spring. I’m not sure that I’m as attuned to the spring chamber buzzing as veteran spring piston gunners are, but I’ll do my best to give a before and after assessment, if that would be of interest to anyone.


    • half,

      Yes, silicone oil would work just as well. I just chose to use Pellgunoil because that’s my default choice for leather piston seals.


      • B.B. RidgeRunner inspired this question. You have said many times that all spring guns diesel to some extent, so I’m surprised at the low power. Now my question is if you use silicon oil that does not diesel, would you get less power all else being equal because you have less dieseling?

        • Roamin,

          First of all — I didn’t say that silicone doesn’t diesel. It does. What it doesn’t do AS OFTEN is detonate.

          The first shot out of this rifle went out at 1,100 f.p.s. Shot 2 was over 1,000 f.p.s. It took four shots at least to get it down to where it is now.


    • Half,

      BB is a “half” step ahead of me. I was going to tell you I use silicone oil all the time on my leather seals. Works great and does not diesel.

      P.S. Any excess will “blow out” and lubricate the inside of the barrel and the transfer port seal. It is also great at helping to seal tap loaders.

    • Half

      Would be fun to see how your Diana 45 wakes up after being idle for years. But do you plan to shoot it with the leather seal dry as a “before” starting point?


      • Decksniper,

        I may risk a shot or two in the “dry” state, just for comparison, but I don’t think I want to do more than that just because I’m worried about abrading the leather or doing some other damage. I worked in Industrial Maintenance for over 40 years and saw lots of leather seals just totally chewed up due to lack of lubrication. It can take mileage off the seal like “burning out” shortens tire life.


      • Half

        While we would be interested in knowing the full before and after, you may decide to lube it before shooting even once. However you go about it I for one look forward to your findings.


  3. BB,
    I think I am becoming more like Yogi. I know it is scary, but I seem to prefer messing with sproingers more than PCP. I really need to tear into that Tomahawk.

    The PCPs at RRHFWA will not be going away though. 😉

    Trigger 1
    I have more to say about the trigger in a but (moment), but for now, let’s move on.

  4. For some reason, I have been seeing a few of these 45s offered on ebay lately. I ended up with a Diana 35 (Actually a Winchester 435) with two adjustment screws in front of the trigger. How are the 35 and the 45 different, and how are they similar? As I commented before, I fear mine has a broken spring.

    • Roamin,

      They are as un-alike as two airgun triggers can be. This one is modular. Yours is pieces held together by an outer assembly shell — the spring tube.

      The only similarity is both of them release the piston.


        • Thank you, again, B.B. my question was a bit more general. Are there other differences like tube diameter or piston stroke, advertised fps or fpe, in addition to the trigger adjustments that would really allow a buyer to compare and contrast the two guns? They both seem to be full sized rifles. I was a bit surprised when I got my Winchester 435. It was bigger than I imagined, even after reading your previous reports on the 35. But I really like it and I look forward to replacing the spring (or at least removing any broken pieces) and giving it an all over lube tune. It may crunch a bit when cocking, but it is a really easy cocking gun right now and a pleasure to shoot offhand. It came to me with a nicely adjusted trigger. I don’t have a trigger pull gauge (yet ;o) ), but it has a a light yet not insubstantial first-stage pull to a definite second stage, and with a few additional ounces of pressure, to a crisp release. If you decide not to take a shot, you can back off the first stage and start over from the beginning without worrying that the sear is partially pulled. And best of all, it turns out to be not pellet picky at all! I have an R7 which is admittedly nicer, but the 35 is finding a soft spot in my old-fashioned heart. Especially with the vintage Diana peep sight I bought that has the grooved foot.

          Sorry for all of that. Just interested in all the differences and similarities between the 35 and the 45.

  5. Hello all! Hope you are all looking after yourselves and things are ticking along nicely. : – )

    It’s been a while ( I got sick, then better, then sidetracked, then bought an eReader and hunkered down with quite a few good stories…)
    So I have made yet another thumb hole stock out of one plank of 30+ years old pine, this time with a swept back grip. and much less frills ( no quick adustable LoP etc ) . I bought some rotary rasp tools and they work well in my battery drill ( used to be 12v DC now it’s 22v DC, now it motors! ) so I had to make a new thumb hole, right?
    and a hard wood version will come next when I get over to the wood place!

    And then, I was sitting at the PC doodling my ideas down in MS Paint ( free Crayon Aided Design engineering CAD program…) and I thought: what about a skeletal stock made out of steel flat bar ??? and after a few designs I decided I liked this one. Two socket cap screws hold it on and it’s easy “on easy off”, packable SemiBullPup. Will probably Silicone Sealant the grip and the stock butt and /or some kind of wrap. Cheek rest needs to be designed. as well as a bending bar or press brake to bend up the steel work. Should be interesting to see how easy it is to bend the steel. Local steel place does 20mm x 3mm by 6m, I reckon that will do the ticket. ( Can make the LoP quite long with little hassle…)
    The rifle base chassis design is now mature and will stay like that until I decide to build a whole new one…. so the wooden stock and the steel stock all bolt up the same.
    OK I will stop talking now. : – )
    PS This is what got me inspired again: https://www.youtube.com/watch?v=X_O1-chxAdk

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