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Education / Training Diana model 5V pellet pistol: Part 2

Diana model 5V pellet pistol: Part 2

by Tom Gaylord
Writing as B.B. Pelletier

Diana 5V pistol
Diana model 5V pellet pistol.

Part 1

A history of airguns

This report covers:

  • RWS Hobbys
  • JSB Exact RS
  • What is dieseling?
  • Sig Match Ballistic Alloy
  • Cocking effort
  • Trigger pull
  • Next
  • Observations

Today we look at the power of my old Diana model 5V air pistol. I expected to see results in the same class as the BSF S20 and Webley Hurricane, but perhaps a little slower because of the age of this airgun. I reckoned somewhere in the high 300s, at least.

RWS Hobbys

The first pellet I tested was the RWS Hobby, which is often the standard for velocity in an airgun. In the 5V Hobbys averaged 397 f.p.s., which I think is a pretty healthy result. The low was 387 and the high was 408 f.p.s., so the spread was 21 f.p.s. At the average velocity, this pellet produced 2.45 foot pounds of energy. I will add the Hobby fit the bore pretty tight.

JSB Exact RS

Next up were JSB Exact RS pellets. This domed pellet fit the bore better and went in deeper. They averaged 420 f.p.s., despite being 0.33 grains heavier. The spread was from 396 to 431 f.p.s., which is 35 f.p.s.. At the average velocity this pellet produced 2.87 foot pounds of energy.

I want to note that of the three pellets I tested, this was the only one that caused the pistol to diesel. There was no noice, but the barrel filled with smoke with every shot. Whether that is important will have to wait for the accuracy test, I guess.

What is dieseling?

Dieseling is normal in spring-piston airguns. Thgose that shoot over 400 f.p.s. all do it to some extent. Dieseling is the rapid combustion of tiny oil droplets from the heat of compression. According to the Cardew team of father and son who wrote the book, The Airgun From Trigger to Target, dieseling is a normal function of spring-piston airguns, once they reach a certain power level. It adds a certain percentage to the muzzle velocity.

Don’t confuse dieseling with detonation, which is a loud explosion of rapidly burning oil. Dieseling produces smoke without any flash or loud explosions.

Sig Match Ballistic Alloy

The last pellet I tried was the lightweight lead-free Sig Match Ballistic Alloy pellet. They turned the 5V pistol into a screamer, with an average velocity of 485 f.p.s. The spread went from a low of 469 to a high of 489 f.p.s., which is 20 f.p.s. At the average velocity this pellet generated 2.74 foot pounds of muzzle energy.

Oddly enough, even though this pellet was much faster than the JSB Exact RS pellets, there was no indication of dieseling. The pistol must be right on the cusp of what it takes to diesel and the RS pellet must be right for the job.

Cocking effort

The 5V cocks easily for me. I measured the effort at 23 lbs. Those other powerful spring-piston air pistols I mentioned earlier all cock with over 30 lbs., so this one feels light.

Trigger pull

The trigger, on the other hand, is extremely heavy. My gauge goes up to 12 lbs. and this trigger is much heavier than that. I estimate 18 lbs. It’s like the trigger on the Swivel Machine Corp Stealth arrow launcher, which has the heaviest trigger I have ever tested.

However, as I was shooting the strings, several shots were lighter by about half. That gave me some hope that this trigger will respond to some moly grease in the right places.


Normally I would test accuracy next, but given how heavy this trigger is, I think I will take the action out of the stock instead, and see if I can do anything with the trigger. I don’t want to disassemble the action, so I’m hoping to find a way to grease the trigger and sear once the gun is out of the stock.


I wasn’t expecting this pistol to be as powerful as it is — especially not after reading Fred’s review of his .22. I guess this one is fresher than it appears. I hope it is accurate.

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.

41 thoughts on “Diana model 5V pellet pistol: Part 2”

  1. B.B.

    Looks like you were very conservative with your estimates regarding velocity. How did the Sig Match Ballistic Alloy fit the bore compared to the other two? I do wonder if the RWS Hobbys would gain anything if you loaded it in deep with the aid of a pellet pusher. Will the process of applying moly be part of the accuracy article or will it merit its own article?


  2. BB,

    I should be very interested in seeing the trigger assembly on this, most especially since the trigger is below the cocking lever. I should be quite an interesting mechanical design.

  3. B.B.,

    Very nice on the performance. Depending on how easily this thing would come apart, it would be (real) tempting to go further and give it the good “once over”. But,.. that is just me.

    I am amazed at the size of these springer pistols. I remember looking a few up after reading Part 1. Some are even 18″ long. That, to me, would seem quite awkward. I remember seeing a Benjamin (I think) still in the box at a local gun shop and the box was “huge” for an air pistol. Still, it would be fun to play with one.

    Good Day to you,.. and to all,…. Chris

  4. BB,
    Once you pull the grip you will be able to access the trigger components easily. Note the trigger spring is in the grip. Shouldn’t fall out but just be aware. Are you cocking by holding the spring tube? I have seen two of the Diana V’s with the grip broken in half. Mine included. Nice velocities.

  5. BB

    RidgeRunner’s comment above about the mechanics of this gun leaves me with a couple of questions. How much of an arc does the barrel travel through to cock and is the trigger guard shaped as it is to somehow accommodate that movement?

    • Halfstep,

      The barrel comes down just past 90 degrees — maybe 95. The triggerguard has nothing to do with the cocking. It’s just a piece of sheetmetal that’s been formed to need just a single screw to hold it ton the grip.


  6. BB

    Thanks for clearing that up.

    This is a little off topic, but has anyone seen the new review of the QB Chief on the AEAC channel? Steve manages to put 5 .22 cal JSB Jumbos into 1.19″ at 100 yards. They went: FPS 816,816,819,818,and 811. I know it’s only 5 shots but, ITS AN UNREGUTATED CHINESE GUN AT 100 YARDS FOR 180 BUCKS!! Sign me up!!

    In your report on Archer’s QB family repair manual, you mentioned that your earlier evaluation of a QB must have been done with a gun that was tuned before it was sent to you. Could you review the QB Chief and see what results you get with a gun that you can be sure is stock? Not sayin’ that Steve was fooled by a tricked out gun in the AEAC report, but his results are almost too good to be true.

    • Halfstep
      Yes, I saw that video too, pretty impressive. I think Steve does a pretty honest review. I also watched a video review done by Rick Eutsler. He shot very good groups at 25 yards with Chief and was very impressed with the rifle too. He wanted to push the test out to 50 yards but it was too windy that day. Looks like a real contender with the Maximus. Oh, and there was a “head to head” review of the Maximus vs the QB Chief on Airgun Depot’s vault. Nice comparison. Hope it’s okay to mention the name here.

      BTW, I am sure many of the folks here in the forum have been to airgunweb.com and watched Rick Eutsler’s reviews. Rick has had some medical issues and ended up in ER with no medical insurance coverage. A “Gofundme” page has been set up for anyone wishing to help Rick out with these exorbitant hospital costs. I think we as airgun people should help Rick out if possible. Here is the link to his story and the page: https://www.gofundme.com/rick-eutsler

      • Geo791,

        I wasn’t accusing Steve of anything, just pointing out that apparently, cherry picked or modifided guns sometimes (unwittingly) get reviewed. I love Steve’s video reviews because of his style of presentation and because,since his reviews are widely spaced, he has the time to test many,many pellets ( mostly off camera) and that’s how I check my guns. Ideally, I’d like to find ALL the pellets that are accurate in my particular gun. Thanks for the link to gofundme. I’ll make a contribution. I like Rick’s channel a lot,too. Do you know the nature of his illness?

      • Geo791,

        I forgot to say that, after rewatching the video, I picked up on a point that I missed on the first go around. He says that he had to shoot many tins of pellets to get the valve to settle down, so I doubt that the gun had been dickered with before he got it.

        • Halfstep
          I read some of the comments to the review Steve did. In one of the comments Steve mentioned that he received two QB Chiefs for review but that one of them was cosmetically “poo” and he sent that one back without further testing. Does that mean it’s 50/50 chance of getting a good one? Maybe.

            • Halfstep
              I know what your hinting at 🙂 FedX tried to deliver my RWS 34 on Saturday 7/22 but I just missed him by minutes. I have to sign for the rifle or they won’t leave it. I passed the FedX truck just coming from my house….darn. Oh well, today I am waiting, as I write this, for the FedX truck to come. It’s is supposed to be delivered this afternoon. They don’t deliver on Monday here so I have had to wait an extra few days.

  7. B.B.
    Here’s a question for you that has been perplexing me lately.
    Of my small accumulation of air rifles, a couple of the most accurate are the cheaper Chinese made rifles, e.g., a Beeman RS1 (and, RS2) and my B3-2. Add that to the previous comments on the QB Chief and I start wondering what has the most influence on air rifle accuracy – the overall make of the rifle like a Diana, or the quality of the barrels. I’m starting to believe that the Chinese can make some very fine barrels (as well as sub-par) so, I guess my question is: with all things considered, how much toward accuracy does the barrel contribute?
    Larry in Algona

    • Larry,

      I believe the barrel is 75 to 90 precent of the accuracy of any gun. Of course some firearms have poor bedding that pushes against the barrel as it heats up in firing and that pushes it off target, so a poor bedding job can be a big factor.

      Triggers, stock fit and sights are all minor where accuracy is concerned. At least that has been my experience.


        • Larry and Halfstep

          I almost just let this go. But got to say my 2 cents worth. And maybe more.

          Been in the machining world for more than 30 years now. Seen alot of how manufacturing works. Cutting tools, cutting oil for the machines and the machines making the parts and the up keep.

          Seen what happened when our company and other companies that was in competition with the company I worked at decided to have pars made in China. They did get the parts made cheaper that’s for sure. In more ways than they thought. Quality control over there is a unrecognizable word. Half or more of what they made didn’t meet the print specks. We had to remake it. Plus get behind on other parts we was suppose to have ready to be shipped.

          Here’s the question. Did they learn from their mistakes. Answer is yes they did. They do not do that anymore

          What I’m basically saying is that the repeatability to make a good product is what happens. You could look at the parts and see they was running their tools as long as they could when it was definitely need past time to change.

          As you can tell I’m not a big fan of Chinese stuff. Maybe they are getting better though too. I guess we will see.

          And just my opinion. And other people’s opinion on the I guess we will say Chinese air guns is welcome. I’m sure that there has to some good points about them.

          • GF1,

            I figure a 200$ gun,.. x 10,000 guns sold = 2,000,000$.

            …………. 100$ gun,.. x 100,000 guns sold = 10,000,000$

            From a Chinese factory owner’s standpoint, that bottom figure looks better.

            If they ever made one, and it was well tested and proven with a good track record,.. then yea,.. maybe. I am no Economics’ Major,.. heck,.. not even a Economics’ Newbie, but I still like the bottom figure. I am sure there is some solid economic theory in there somewhere.

            Yea, they (can) probably make the “best of the best”,… but why?

            To repeat a very recent phrase of yours,… “And just my opinion”. 😉

              • RR
                Sounds like Crosman guns or parts are made in China from what you said.

                What guns and what parts of the guns are made in China is what I would like to know.

                • GF1,

                  It is not so much Chinese parts to me with Crosman, but what they do with them. They really need to throw away their sproinger trigger assembly and start all over.

                  • RR
                    I believe what your talking about with Crosmans spring and nitro gun triggers is more of a engineering design issue. Not a quality issue. And I have to say their pcp guns on the higher dollar guns have great triggers.

                    I was talking quality with the China guns. It’s about repeating the part they make that the engineer designed. That’s the problem I have with the China gun’s.

                    • GF1,

                      We are slightly off frequency here. What I was referring to was his comments concerning economics and why Crosman does not improve their products. What is truly tragic is that should they introduce just one model with an improved trigger assembly, the general populace would be clambering for that trigger to be on all of their models.

                      Fortunately companies such as Weihrauch know they cannot compete in the volume game, so they build products that offer quality. Even with them, they have reduced the prices on several of their “low end” popular models.

                    • GF1,

                      It is not an engineer problem. They have engineers. It is accounting. The cost of changing the supply chain, production, etc. is such that they would not want to do such, even if the trigger assembly would cost the same.

          • GF1
            I worked for the hydraulics division of Parker Hannifin for forty-three years until retiring in 2011. We used CNC machining centers almost exclusively to make our parts. Our problem was capacity. We couldn’t keep up with demand for our hydraulic piston pumps. Our purchasing department, in their infinite wisdom, decided to out source one of the parts called an impeller. This part cooled the pump internally. Anyway, they went to Mexico for a supplier. I programmed the Zeiss CMM to measure these parts. The ones coming from Mexico, I had to edit my program to create one that could check the parts from Mexico. The hole locations were so far off the probe could enter the hole! Here is the thing though, our managers weren’t the sharpest and we continued to purchase those defective parts for two years. They were so bad that when they arrived in receiving they just bypassed inspection and went straight to the toolroom for rework. We kept sending the Mexican supplier the reports informing them of the out of spec dimensions but they never ever made them any better. Finally, them moved them to a supplier in Detroit…never another bad part. Nothing good comes out of Mexico. We sent our gear pump manufacturing down to them and they killed that product line altogether.

            China, that’s another story. We made a part called a swashplate for the piston pumps. We had like four sizes of them. They were very precise parts with very close tolerances. They sent one of those parts to China. The first lots that we got were dimensionally very good but the finishes and bearing ratios were crude. Soon they fixed that problem and those parts were actually better than the ones were making out in the shop. So China has the expertise if you get the right supplier. I saw a lot of good parts come in from China and they are capable of making quality parts. Mexico…not so much. With the big three auto companies now opening divisions in Mexico, I think you will see a definite degradation in quality. Guess I’ll just keep my Volvo.

            • Geo
              I can relate to everything you just said.

              And those are the parts we use on the machines I spent those years on. We have the variable displacement hydraulic pumps on or machines like that swashplate your talking about. As well as the valves. Our newer machines use bosh valve’s. Have you ever heard of Hydromat rotary transfer machines? I got to run, set up and learn to rebiuld the first 7 machines that came to America. They are Swiss built machines. They were brought over by Bud Pohlman. That is who I worked for 31 of the years. Started last year at Hydromat that was 2 doors over from Pohlmans shop. They opened a manufacturing shop and I do all the preventive maintenance and repairs on the machines.

              Anyway back to the original topic. Yes I don’t trust quality from China or Mexico for that fact. The thing with China is like Mexico. There is no tool control. They absalutly do not know when it’s time to change a tool. They will run it till it dies. And I just have to wonder if they have any machining fires. I have seen some on Hydromats cnc’s and screwmachines. Most of the time it was operators neglect of changing the tool on time. And of course some was from setting tools wrong.

              My whole thing is that they don’t produce a product that can repeat it’s performance from one gun to the next. And yes I had a fair share of China guns in the past. I know some people like them. Just not me.

  8. When I acquired my Diana 5V it had suffered. The grip was in three pieces. Doug Phillips did a miraculous job of repairing it. However, I only have three of the original four very unique grip retaining screws. Might ANYONE on this blog have (or know of a source for) a replacement screw?

    It is my intention to clean and rebuild the mechanicals before re-assembling the grip and seeing how it performs. Patience is not one of my foremost virtues, but I’m working on it!

    St. Louis, MO

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