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Ammo RWS Diana 45: Part 10

RWS Diana 45: Part 10

by Tom Gaylord
Writing as B.B. Pelletier

Part 1
Part 2
Part 3
Part 4
Part 5
Part 6
Part 7
Part 8
Part 9

RWS Diana 45 air rifle
Diana 45 is a large breakbarrel spring rifle.

This report covers:

  • Cause to reconsider
  • More black tar?
  • What is black tar grease?
  • A quick job
  • Velocity
  • Summary

Today’s report is an unprecedented test. I thought I’d finished the report on the Diana 45 in Part 9, but it still bothered me that I couldn’t get the last bit of vibration out of the gun. I chalked that up to the high number of parts in the rifle’s powerplant. Too many things to make quiet.

Cause to reconsider

Then two things happened that caused me to reconsider. First, while at the Malvern airgun show, I saw and shot a fabulous HW85 that had been tuned by Bryan Enoch. It was stunningly calm. When I talked to him about his tune, Bryan told me that he put a thin coat of black tar grease on the mainspring before he assembled the rifle. That caused me to stop and think — because that tune was perfect.

When I returned from Malvern, I shot my new HW35 for the first time and was startled to find that it had been tuned — or at least that’s what I thought when I first shot it. If you’ve been reading this blog for a couple weeks, you know how that story unfolded. It’s still unfolding, as a matter of fact. I still don’t know yet if that rifle has been tuned or is just smooth because it’s power is so low.

More black tar?

These experiences got me to thinking about whether or not I should have put more black tar grease on the Diana 45 mainspring. I did put on a very thin coat, but it wasn’t much. I didn’t do more at the time because I thought I had removed all the sloppy tolerances in the moving parts. The airgun tuner in me wanted my work to stand by itself — not be supported by the crutch of black tar grease. But shooting the gun after it was tuned told me different. Most of the annoying vibration was gone, but not all. Ten percent remained, and it bugged me.

Then, I thought about my Beeman R1 and the incredible Mag 80 Laza tune that Ivan Hancock sent me. It was a drop-in kit that had a buttoned piston (the first buttoned piston I ever saw, and it was only buttoned at the rear) and a new mainspring that was both longer and made from thicker wire. That spring was uniformly coated with a black sticky substance that looked and smelled like tar to me, so that’s what I called it. With the kit installed, my R1 went from vibrating to dead calm.

I later ruined that Mag 80 mainspring in the Mainspring Failure test when I left it cocked for a full month. That’s 735 continuous hours of being cocked. It didn’t lose much power, but it developed a cant that caused some vibration to creep back into the gun.

Fast-forward to the present. It turns out the best tunes I’ve experienced have all used black tar grease. Why didn’t I put more on the Diana 45 mainspring? I still had the rifle, so I decided to do it — which is the main point of today’s report.

What is black tar grease?

Black tar grease is a viscous black grease that is generally used to lubricate open gear boxes. In other words, it’s for gears that are exposed to the elements. It’s very sticky, so it doesn’t fling off the mainspring when the gun fires, and it’s very viscous, which means parts that are coated with it cannot vibrate. If they try to vibrate, the tar holds them still.

There are probably many different brands of grease that qualify as black tar. I wish I had a brand name to give you but I don’t. I’m still using a jar I bought from Jim Maccari several years ago, and I have a couple more applications left before I have to get more. Maccari’s Air Rifle Headquarters was shut down for health reasons, but I see that he’s opened up a limited site, and black tar is available, again.

A quick job

The Diana 45 was a major pain to disassemble the first time, but this time was different. All I had to do was remove the mainspring.

It took less than 30 minutes to gather the rifle and tools I needed, set up the workplace, break down the rifle, grease the mainspring with tar and button it back together. The first shot told me what I wanted to know. The Diana 45 now has zero vibration! In fact, I compared it to the HW35, and there is no more vibration in the 45 than there is in the HW35 that probably develops half the power. The 45 does have more forward thrust when it fires, but all vibration is gone.

The only thing left is to measure the velocity. We know that using too much black tar slows down a gun. Use a lot, and you’ll lose 40-50 f.p.s. on average. But use just a little and the velocity will remain within a few f.p.s. of where it was without it. So that’s what we want to know — where the rifle is now — both in terms of velocity and also consistency shot-to-shot.


There are 3 different velocities and shot string spreads to compare — the initial velocity and spread before I tuned the rifle, the velocity/spread after the tune and the velocity/spread after today’s application of black tar.

The pellets I tested were RWS Superdomes, RWS Hobbys and H&N Baracuda Match pellets with the 4.53mm head.

RWS Superdome pellets
Before tune………..After tune………..After black tar

RWS Hobby pellets
Before tune………..After tune………..After black tar

H&N Baracuda pellets with 4.53mm heads
Before tune………..After tune………..After black tar
Not tested……………676/46……………….662/29

Some velocity was lost, but not that much. With both of the pellets that were tested before and after the first tune, the velocity is still higher after the tar. I wouldn’t have cared if it dropped back to the earlier mark, because all I was after in this tune was smoothness. And we now have that.

Some pellets shoot smoother than others. Hobbys shoot the smoothest of the 3 I tested, and I find that to be true for most spring guns. Tuned or not, they all shoot smoother with one pellet than with another.


I wrote this last report both for you and also to remind myself of the importance of black tar grease to a good spring gun tune. When you find something that works, it’s best to stick with it, as I plan to stick to my black tar — pun intended.

45 thoughts on “RWS Diana 45: Part 10”

  1. BB THANKS FOR FIXING THE 45 it is a totally different gun now I never shot because it was noisey an vibrated really bad I have shot it more this weekend then I have in the last fifteen years I’ve owned it thanks a bunch . Johnny

    • Johnny,

      I am so glad I was able to get that tune how I wanted it. You saw the difference right away, which is my test for success. Now you have a wonderful air rifle to have fun with, and that is what it is all about.


  2. B.B.,

    I understand that a high viscous grease will adhear to parts and,..not “fling off” as the parts move at high speed. I can also see where it would reduce friction at the spring i.d and o.d as well as the spring ends to allow the spring to twist freely while in the compression and release states of movement.

    Q:..What I do not understand is how black tar grease, or any viscous grease for that matter, would (stop) vibration in any way? If you could, please elaborate on that with either known facts or,…at least some of your best theories.

    Q:..Also, with regards to tune kits, what are your thoughts on using black tar in tune kits that have alot of plastic in them such as what the Vortek tune kits have?

    Thank you very much for your imput, Chris

    • Chris,

      This is something you may need to experience to understand.

      The Vortek kits I have used have not needed black tar. Their plastic parts are both inside and outside the mainspring and they do the same thing tar does. I have one in my Diana 34 and it is very calm.


  3. As a side note, there was a little trivia quiz in the local paper a while back. The question was,…”What is the slipperiest substance on earth?”

    “Black Tar” was the answer.

    We got a lot of smart people here. I am sure someone knows what this substance is and where the common man can buy it. At least what the commercial name is.

    • ARH spring tar is far from slippery, actually. It’s quite sticky and will add some friction to fast sliding surfaces.

      I think molybdenum disulphide is still at or near the top of the list for ‘slippery’, friction reducing molecules, especially for sliding steel parts. That’s where the term ‘moly’ comes from in moly paste or moly grease that we use for our airguns.

    • Chris,

      some refer to this “tar” as open gear tractor grease. When I have used it, I wear latex gloves. The gloves are definitely needed if you ever apply moly grease as this black stuff is so tenacious that it takes days to get it off your skin. If you go to the local tractor repair/supply center, they may be able to help you outwith the grease if Jim M. isn’t in business. I personally prefer to deal with Jim Maccari. He has the molybdenum disulfide grease as well.

      Fred DPRoNJ

  4. B.B
    I’m glad more tar worked. I think my velocities are lower that yours, and the original bent main spring produced much more velocity and buckets of buzz and vibration. It used to sound like a screen door on cocking. Its now a smooth calm shooter I can live with smooth 10 ft lbs instead of buzzy11.5.
    Do you know if the clear tar or silicone grease does the same thing as the black tar?

  5. Momentary diversion, just in case it is something not at my end:

    The SAGE RSS reader I’ve been using for the comments has been reporting an XML Parsing Error all week-end and this morning. Unfortunately, it doesn’t give any indication of which post may be causing the problem, it just quits with no message headers displayed.

      • Twotalon, I hope you Internet Explorer get better. Of course, Firefox and Chrome await your command.
        Well, it finally happened. This past weekend I began experiencing what you described with your Titan. I pull the trigger and all I get is a little pssst then nothing. I tried it a few times before setting it aside, with the breach open. ~ken

  6. BB– I have a binocular that I can,t use in the winter. As soon as the temp goes below freezing, it is impossible to focus. The grease freezes and the focus lever cannot be moved. Will low temperatures affect black tar and other air gun lubricants and lower velocities? Ed

      • Surely, an anti-freeze type of gun oil has been invented by now. What about Ballistol? It seems capable of just about everything else. Don’t the freezing points of oils generally differ from water. I couldn’t say why, but I would guess that their freezing points are lower.


        • Matt,

          You wouldn’t use Ballistol for this application any more than you would lubricate a motorcycle engine with watch oil. The viscosity is all wrong.

          Try shooting a gun that has been tuned right before you make any pronouncements. if you will come to the Texas Airgun Show on August 29, I will let you shoot a couple nice ones.


  7. That black tar sounds like a mess.

    Mike, thanks for the interest in my M1. Yes, I’ve hard that a slower-burning powder like IMR 4064 can apply more force to the operating rod. However, I am in the toils. A gas adjustment system has been installed on my gun. I’m supposing that the adjustment would not consist of drilling out the gas hole larger, so it must consist of some kind of sliding cover that can reduce the size of the opening. Is this how this device works? I’ve heard of adjustable gas systems on M1s and would guess that they work on a similar principle. The reduced opening for the gas port compensates for the greater force of 4064 allowing a range of adjustment and tuning. Supposedly, my gunsmith adjusted the system to a precise load. Except that he didn’t because not only does the gun not shoot particularly well, but it jams. Unfortunately, the gunsmith is not around to explain things since he has retired. And even blog poster and master machinist Derrick is not sure how the system works. So, my only recourse is to try to reduce the force from what looks to be an excess by dropping the powder charge.

    A variety of observations make me think that the gun is getting too much gas. One that I have not mentioned before is that on the last outing, the cases tended to eject more forward than sideways. And one even came out to the left of the barrel!? Doesn’t that mean too much pressure? Fortunately, the last outing does seem to bear out my theory by giving better performance with reduced powder. I hope to confirm soon. As to damaging the operating rod, the gunsmith claims to have licked this problem separately. The obvious solution to reinforcing an op rod is a track. But how to design a track for an op rod with a bend that slides back and forth. The answer that I was able to glean is a track in two pieces that is somehow designed to resist a kind of upward movement of the op rod that it makes under stress. And the track is fit so carefully that it protects the sliding rod without binding it. You can see that I am in deep waters and do not want to mess up this rifle. On the bright side, the gunsmith said that there is very little I can do to hurt the rifle–without purposely undoing his modifications. So, I’m hoping to solve the problem just by adjusting the powder.

    But in the midst of all this, my Saiga AK gives me enormous satisfaction. There are few things more certain in this world than that the rounds will chamber in this gun. There isn’t the slightest hiccup or problem of any kind. I didn’t think that feeding could get any more reliable than a Mosin, but it seems to be even better in the AK.


    • I really can’t comment on the adjustable gas system on your M-1. I haven’t seen one. The match rifles I have seen were mostly glass bedded, with trigger work, match grade barrels, and National Match sights. Also, IMR 4064 isn’t too slow for the M-1. I think the powder I mentioned was IMR 4350 which burns a lot slower. I mostly use IMR 4985 and IMR 4064 in my M-1. But, other than a match grade trigger and National Match sights, it’s GI. I haven’t seen a M-1 with as many issues as yours. At the end of the day, you may need to find a Smith that works with “On the Edge” match grade M-1’s

      I have not shot the new Bulgarian AK yet but it looks like a winner. The AK’s claim to fame is it’s reliability.


      • Mike, I think you may mean 4895, not 4985.

        Matt, I think Mike is right. I haven’t seen a Garand with as many problems as yours either. Why in the world did you start fooling around with (I assume) a working gas system anyway? Supposedly, IMR 4895, precisely charged by-the-book replicates the factory charge with the notable positive side effect of not ruining your operating rod. And makes the M1 reliable, too.
        Just as a suggestion, listen to Mike and spend the money on glass-bedding, match sights, and match triggers. I think you’ll find that much more price efficient.
        And write off you former “gunsmith.” He seems to have been problematic for how long? A year or more? It’s time to move on.

  8. Chris, USA
    I would try going to a heavy equipment shop like a Caterpillar or Case as they have equipment that use exposed gears that would require that black tar type grease to be used on them.

    Another good thick fibrous type grease that would not sling off parts is made by Shell oil company and is called Shell Aeroshell grease and is a yellow colored grease that has a stringy type fiber quality to it. It is used on airplanes on landing gear retracting gears and many other places that require a grease that will stay in place at the speeds that commercial airplanes land at IE. 150 plus mph. It may be found at a local auto parts store possibly and if not try your local airport garage for how to purchase.

    You may also search it on line for either type grease and find it that way.

    Good luck


    • Buldawg and all,

      Thank you for all the grease related comments. I checked Mc.Master Carr catalog and even Wikipedia. Lots of good info., but none that show “black tar grease” by itself. It,.. (tar)
      seems to be an additive, rather than a stand alone.

      I am still curious to know how grease on a spring would be able to reduce (vibration). Surely there must be a physics related explanation. That however, is beyond me.

      Till then,..if the need arises,..I will “just have to try it”.

      On a side note, while looking for “moly” grease this weekend,..I ran across a brand that boasted 3%. Which begs the question,..what is the moly % ranges of molys offered? Oddly, Mc.Master Carr did not offer this info., but did offer a lot of moly. blends.

      Thanks again, Chris

      • The grease, just by clinging to the spring coils, adds mass to the coils and will actually lower the resonant frequency of its internal vibrations.
        In addition, the thick gooiness of it tends to absorb energy and dampen high frequency movement.

        If you play a stringed instrument you already know how a buildup of finger oil will kill the sparkle of a set of strings. Imagine how spreading peanut butter on a guitar string would dull and mute the sound!

      • Chris, USA
        I use a grease that is sold and used by Nissan to prevent disc brake squeal by being applied to the backside of the pad between the pad and caliper and is designed to absorb the very fast frequency vibration of the pads in the caliper that cause braked squeal noise that is ear piercing.

        It is a very thick and sticky grease that has copper and lead powder infused into it. it can be bought at any Nissan dealer and is called PBC grease, it comes in a plastic mayo sized jar with a screw on metal cap with an applicator brush in the cap so you don’t have to get it on your hands. I have had good success with it in my spring guns.

        I do not know the cost as it is provided to service techs for use when performing brake work and since I worked for Nissan a couple years ago I have some left, but it is most likely fairly costly but it will also last you a lifetime.


  9. BB,

    Is the grease a permanent fix or is it something that has to be maintained? Do you have to tear down the gun and reinstall the grease after some unknown number of shots?

    I can see how the tar or grease would dampen the harmonics of the spring. I would be concerned about the grease getting all over the internal parts of the gun and essentially ruining the airgun. That said, I could just be ignorant.

    • Spidey,

      The grease is as permanent as anything can be. It will last as long as the piston seal, for instance.

      Yes, it does get on everything, which is the intention, because when everything is coated there can be no vibration.


  10. Mr.Gaylord,with all synthetic high temperature greases we have today is there one that you like? I just came across some Lucas Firearms oil at a local auto parts store. I called Lucas oil and talked to a representative and he assured me that this oil will not harm plastics,rubbers,or silicon rubbers. I tried it in the compression tube a drop or two and believe it or not no DIESELING. This was in a magnum springer,and any oil or grease that I have used always dieseled. Maybe this was just a fluke? Have you seen this stuff yet? From what I was told its made for full and semi auto firearms. I am no chemist,but my understanding is that this oil has a lot of PTFE (this is Teflon ) in it? If you try it let us know how it works for you.

    • Rich,

      I haven’t heard of Lucas Firearms Oil. It sounds like a synthetic that has a high flashpoint, which is what is needed for compression chambers.

      There are so many oils on the market that I will never get to try them all.

      Thanks for the info on this one.


  11. B.B.:

    Is “black tar” the same thing as the “axle grease” we used in tractor gear boxes when I was growing up?

    I hated working with that stuff. We used to buy it in 5 gallon drums.



    • Jim,

      I invented the term black tar. Until I used it, nobody called this stuff by that name. It is not an industry term.

      Your tractor gearbox grease sounds right. If it is thick and tacky, then it will probably work.


      • B.B.,

        My apoligies for saying the answer to the afore mentioned trivia quiz was “black tar”,…..it must have been Tar Grease. It’s been a few months since I read it.

        Sorry to “de-rail” your article a bit. Seems like it was a topic on a few peoples mind at any rate though.


  12. To all,

    Posted earlier, but no show. Soooo,…for an (much) abbreviated version,…McMaster Carr and Wikipedia do not show black tar as a stand alone lubricant. Rather, an (additive) that has lots of variations/formulations.

  13. Open gear lubricant…cheap enough to be honest, I would have thought a chain lubricant (compatible with o rings) would have been good….I’ve got some Castrol Chain wax somewhere that I’m thinking of giving my HW77 spring a little anointing with when I fit some Delrin guides……it’s a real comedy boinger
    I can’t help feeling all the bind it tight and cover it in sticky jollop, though effective, is missing the point…..a TX or LGU isn’t bunged up with goo……heck Tony at Sandwell Field Sports is one of the UK’s best tuners…..and his rifles are all but dry
    I think this sort of tune cures the symptoms, not the disease and a spring with a little preload, not too much, and, critically, allowed, or encouraged to rotate, either of itself or with the piston body a la Walther…..to expunge it’s final energy without vibration is the way forwards……we used to do it with penny washers, two each end of the spring, polished on a whetstone with the thinnest smear of Moly betwixt them…..the boing and vibration is only the spring fighting itself, you can grip it still, or you can stop the fight……those seem to be the two basic tenets of tuning…..however the latter method does allow the use of a lighter spring without major energy penalties
    I’ll be in the guts of my 77 next week

  14. Hi BB,

    Just to ensure understanding of what I use, it’s tight fitting guides as the main item to kill vibrations. On the HW85, I did use some ARH spring tar, along with other lubricants. Now those are not applied heavily, but very sparingly but I don’t do the same on every gun. I’ve tuned others and used no tar whatsever and still got a super twang free shooting rifle. The key component to both of those are guides that fit just right to the spring. Too tight, and it’s too slow, too loose and it vibrates. The tar. moly, or other lubricants are just that, a lubricant that I am just barely appling to do it’s job and no excess.

    No…don’t get the idea that my tunes are smooth because I slop on the tar and it fixes everything. That would be totally the wrong idea. My tunes are smooth because I go through every part of the gun and do a lot of stuff to it, machining my own parts out of different materials and things are fitted just right and proper lube used where I apply it but nothing is over tarred. I can do the same thing with other lubricants, and each has it’s use and preference of application.

    • Bryan
      I agree that the lubes are just that lubes and by themselves do not make a smooth springer. It is as you say a combination of several thing working in unison and mostly having the right fitting guides on the spring that make the most significant change in the spring performance and noise harmonics when shot.

      Its just the same with building fast bikes and cars as anyone can throw a bunch of go fast goodies at their vehicle but if the parts are not selected to work together then you end up with a slow ill running and cantankerous undependable vehicle that is more of a chore to drive than a pleasure which is what they were after to start with so knowledge and experience are always the best tools to work with and provide the best results in any venture you may pursue


    • Bryan,

      This always happens when I write about something. People discuss it back and forth until is seems as if it is the only thing in the world. I wrote extensively about removing all the loose tolerances in the powerplant before selecting a lubricant. It just happened that in the Diana 45 that I tuned, there was some residual slop I didn’t get out, and the additional black tar got rid of it.

      While it is possible to removes all vibration with tar, alone, it isn’t the right way to tune an airgun. Velocity will also be lost. If you recall, I spent a lot of time discussing the piston buttons, and the rear spring guide on the 45. I think the piston sleeve and forward spring guide is where the slop remained, but the 45 is so complex that I can’t be sure. If it was a Weihrauch it would be so much more straightforward.

      I also did not mention the polished bearings, front and rear, that cancel the spring torque. I wanted to leave some things for when I report on the R1 that you are tuning.


  15. Matt- M1 rifles are very rugged. I bought my first M1 in 1962. It was a former lend lease to Britain rifle, pre Pearl Harbor date, straight cut opp rod, lightly pitted bore. I won a 3rd place medal in the first big bore match that I entered (2 weeks after I got the rifle). I shot thousands of reloads in 20 years– 55 g H 4831, 180 Sierra match bullet. The rifle grouped 2″ off a sandbag , and the rod never bent or broke ( I still have and shoot this M1,) but I retired the original rod recently, Several years later, In 1972 I got a second M1, a Winchester that had been accurized to N. M. standards. It shoots the same load into 1 1/2- 1 3/4 ” groups. Again, no problems with the rod after thousands of rounds. When the 90 lbs of surplus 4831( that I bought in 1961) was used up, I began to reload with 4895 , 3031, 4198. I can no longer compete in position matches (arthritis problems), but I still enjoy shooting these rifles. If I had an M1 like yours, I would have a competent gunsmith take it completely apart to see how it was modified, and to see if its problems can be fixed. Ed

  16. Matt– PS- In all of those years, I have had to replace 2 parts- a broken firing pin and an ejector that went into orbit when I took the bolt apart for a thorough cleaning. Ed

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