What is accuracy?: Part 1

by Tom Gaylord
Writing as B.B. Pelletier

A history of airguns

This report covers:

  • The big question
  • Epic experiments!
  • Shooting Gibraltar
  • Use the best barrels
  • Rotate the barrel
  • Damage the bullets
  • Are bullets balanced?
  • Did Mann learn anything?

Chris USA suggested today’s topic last Friday, when he asked my about the tantalizing results I got from the Webley Mark II Service air rifle. Among his comments, he said this, “Perhaps the biggest thing to consider,… and maybe more accurate,…. it is just plain LUCK. Maybe, it is just the plain and simple fact as to how the pellets flew and just happened to be where they landed. So yea,… I would be interested hear your thoughts on what would appear to be sporadic anomalies.”

Among the “sporadic anomalies” he referred to was the last group, where 3 shots went into a tight cloverleaf and the other 2 were wild. What causes a rifle to do that — to put several shots so close together and then throw the others far away?

Webley Mark II Service Hobby group 2
This is the target Chris referred to. Why are 3 pellets so close and the other 2 so far away?

The big question

I told Chris he had just asked the big question — the one people have been discussing since the firearm was invented. It all boils down to the title of today’s report, What is accuracy?. I told Chris that Dr. Franklin W. Mann spent 37 years of his life experimenting to discover the answer. He wrote a book about his findings titled, The Bullet’s Flight from Powder to Target, whose subtitle tells more about what is inside — A STUDY OF RIFLE SHOOTING WITH THE PERSONAL ELEMENT EXCLUDED, DISCLOSING THE CAUSE OF THE ERROR AT TARGET. This book was first published in 1909 and contains detailed descriptions of the fascinating experiments that Dr. Mann conducted to test his many theories.

I would suggest a different title for this book — Why don’t all bullets go through the same hole? That is the underlying question we all have and it’s what keeps our sport so fascinating.

Epic experiments!

Dr. Mann spent a fortune testing every concept he could dream up to find why bullets did not all go to the same place. One notable one was his benchrest.

Shooting Gibraltar

I’ve been told hundreds of times that I need to test airguns in a vise. I “just don’t get it” that a vise is the only way you can be certain the gun is completely out of human hands (true) and can therefore be most accurate (doubtful). Dr. Mann built such a contraption. It was a 3,500-lb concrete pillar he called the “Shooting Gibraltar.” It stood 26-inches above ground and extended 40 inches below ground to rest on gravel that showed no sign of being disturbed with the last glaciation. On top of this he installed his v-rest and machine rest to hold his barreled actions in complete rigidity. He then constructed a 100-yard fabric tunnel from the bench to the target, so his bullets flew in dead-calm air. This tunnel was curved to allow for the drop of the bullet along the flight path.

fabric tunnel
Mann shot through a 100-yard long fabric tunnel to cancel the wind.

Surely what he did exceeds the requests of even the most particular shooter. And what did he discover? That shooting from a rigid vise made very little difference. His bullets still struck the target with separation that was random and inconsistent. I try to explain that to readers, but if they haven’t read Mann they don’t understand this has all been thoroughly tested before.

Use the best barrels

Franklin Man was a contemporary of Harry Pope, who is acknowledged to be one of the finest barrel makers of all time. Pope made many barrels for Mann, including specialty barrels that were one-of-a-kind masterpieces. One such barrel had 8 screw holes drilled and tapped into the side of the barrel at the muzzle that went all the way into the bore. Screws were put in each hole and then removed to test the effects of exhausting gas before the bullet exited the muzzle. What is special about this barrel is the fact that Pope built it so the holes were exactly between the rifling lands and had no burrs on their inner surface. He bored and threaded them before he reamed and rifled the barrel. They were just holes that in no way damaged the bullet — until Mann wanted to! Pope also provided him with 8 screws that had points, so Mann could purposely distort the bullet before it left the muzzle! He tried numerous experiments with this rig.

Rotate the barrel

Mann also built a special circular action, so he could rotate the barrel in his rest. He then tested it in 4 different angles (0, 90, 180, 270 degrees) of rotation, to see where the bullets landed on target. His best barrel put 4 bullets in 0.56-inches at 100 yards. The worst barrel put 4 bullets into 16 inches at 100 yards. I have been telling people for years that barrels are never drilled straight. Dr. Mann proved it with this test.

barrel rotation
Four shots from his straightest Pope barrel at 90 degrees rotation with each shot produced this 0.56-inch group at 100 yards.

Damage the bullets

Mann also experimented with bullets that were intentionally damaged. He did hundreds of experiments, but they all come down to this — the nose of the bullet is not critical to accuracy. The base is! When he shot bullets with damaged noses, they grouped as tight as did the same bullets undamaged, but bullets with damaged bases became very erratic.

Are bullets balanced?

We worry about the head size and the weight of the pellets we shoot. Dr. Mann worried about the balance of his bullets. To test that he built a machine to spin the bullet up to high speed so it would balance like a top inside a glass Petri dish. Lead bullets were impossible to spin up to speed, so he machined steel bullets. At this point he was testing not the stability of cast bullets but the inherent stability of the bullet’s shape and design. He then photographed the bullet as it was spinning in a darkened room for several minutes. He left the shutter open for up to two minutes to see if any wobble was detectable.

spinning bullet
Each steel bullet is photographed for two straight minutes in a dark room while spinning on its nose. These bullets show remarkable stability.

But he also actual photographed lead bullets that were spun to a slower number of revolutions per minute. With these he discovered inherent instability that could be seen on paper targets when the bullets passed through.

unstable bullet
These two spinning lead bullets from a certain mold show that one bullet (left) is more stable than the other when both were cast in the same mold.

Did Mann learn anything?

Dr. Mann’s experiments were gathered over a lifetime of work. The question is — was anything learned? And the answer is yes, a number of things were learned from these experiments.

1. No barrel is ever drilled perfectly straight
2. Shooting in a vise does not increase accuracy.
3. Damage to a bullet’s base affects accuracy negatively.
4. Accuracy is as dependent on each bullet as upon any other factor.

What Mann did not learn, however, was the single set of rules that guarantees accuracy. He learned that in a batch of barrels all made to the same specification, some will be more accurate than others. He learned that there are imponderables that cannot be named that affect accuracy. In short, more research remains.


This is Part 1 because there will be a Part 2. Some of the material in Part 2 will cover some of the same ground Part 1 has covered, but there will be new material, as well. If there is room I will address airgun accuracy concerns in Part 2. If not, there will be a Part 3.

76 thoughts on “What is accuracy?: Part 1

  1. BB– A Petri dish has a flat bottom ( so that it can be stacked) and a cover. A watch glass ( used in chemistry and biology) is a concave dish. The spinning bullets look like they are in a watch glass. A minor , perhaps insignificant difference in terminology, but so is rifle and gun, pistol and revolver, etc. At least to people who know little or nothing about firearms. I am a former medical lab tec. and my reaction to incorrect terminology is similar to a marine drill instructor, when a recruit calls his (or it,s) rifle a gun. Ed

    • Ed
      And a concave floor would help the bullet stayed centered on the dish. A flat floor would allow the tip of the bullet to walk around.

      So it also appears that he new what objects to use or not use for his tests.

      And I’m still thinking by looking at the pictures of his shooting tunnel that it really would only work for a certain round fired in it. If the ballistics was changed to a different bullet or round I should say would give different results.

      The curve of the enclosure would have to be specific to a given round fired. Or it would need to be bigger around to be able to let the bullet fly without hitting it.

  2. So after reading this. I started thinking. How many have I had that were accurate and how many were not.

    Then I thought more. I see that I really should hang on to accurate guns when I get one.

    So really is getting a accurate gun like playing the lottery? God I hope not. And I’m not saying that as a figure of speech. I’m serious.

    All I know is the accurate ones I have now just went up to a gazillion dollars if I sold them. No worries about the asking price though. Cause they ain’t for sale. 😉

    • Gunfun, I know what you are talking about. I learned the hard way. Years ago I bought my first Winchester 61 pump in 22lr. Very wore looking gun that had been shot no telling how many times. It was so accurate it was unreal. It seemed like if you pointed at something and just thought it, it would always hit what you wanted. It didn’t seem to care what ammo you fed it either. All brands shot very well. Including shorts, longs and long rifle! All very good. Well, silly me, I just figured they all shot that way. I wanted a nicer (Shinier toy) one. I found a near mint condition one. I sold the old one worn out one and bought the pretty one. I went to shoot it and it was just fair. I should say “normal” for this type of gun. I was so upset. How could it be. I figured it must be a lemon cause the old junk one shot so well. So I sold that one and bought another. Again, just normal or fair accuracy. I tired more later on, but never recaptured that magic of the first one. Don’t get me wrong, they didn’t shoot bad, just not super good. So now, if I get something like that, it stays in the safe or on the range/field.

      • Doc
        With you a 100%. Some guns just seem to be exceptional. I learned my lesson for sure. If they are good shooters I’m not going to get rid of them like I use to. The next will probably not be like those exceptional ones.

    • Gunfun,

      I think you are right. I mentioned on here recently I was thinking of selling my .177 Octane. I still haven’t yet, but it’s the least accurate air rifle I own, and it bothers me. (I think that rifle is probably better suited for .22)

      I also think, in our world, finding that right combination of “accurate” can and “best” pellet for that gun is key. Once you find the “right” pellet, do you often try to shoot something else? How many of us here have an air rifle that B.B. has written about, yet our best pellet is something that did not give the best group in the rifle (or pistol) that he tested?

      Jim M.

      • Jim M.
        That’s absolutely right about getting different results with the pellets and guns.

        The best I found is spend time trying. But I like the guns the best that work right off the bat with the first pellet choice I try. 🙂

        That don’t happen often. And some took multiple trys with different pellets. And some just seem never to work out.

        So yep when you get a good one don’t let it go.

  3. And ok I mentioned last night on the weekend blog about me finding something out about co2 that everybody in the world probably already knows.

    It’s simple and not dangerous. And sounds crazy at first. It has helped the Python and m22 but won’t work with the 1077 because the co2 cartridge is enclosed deep in the tube.

    It’s about poi and velocity drop as the gun is rapid fired. A dreaded notorious problem with co2 guns.

    Well here it is. I found that if I take the clip that houses the co2 cartridge in the m22. Or take the left grip off the Python to expose the co2 cartridge.Then cup my hand loosely around it and take a deep breath and exhale it will warm the co2 cartridge up.

    And I found that if the clip holds 18 shots or 10 shots if I take a breath and exhale for half the amount of shots are loaded in the particular guns I mentioned will not slow down by the last shot enough to affect poi.

    So if I got 18 bb’s in the m22 I take a breath and exhale 9 times. The Python holds 10 shots. So I would take a breath and exhale 5 times. Doing this today one clip after another and rapid firing. The cartridge never got cold to the touch when the last shot was fired. And I got one more clip per co2 cartridge.

    It definitely made a difference in accuracy on both pistols. Like I said everybody knows about heat and cold with co2 guns and poi and velocity drop.

    For some reason I tryed it today because I rememberd how we warmed our hands in the winter out hunting. It’s a nice gradual type of heat. I guess it would be called radiant heat. But if someone trys it let me know what you think.

    • GF1,

      I really think you should do more research on this, maybe for the next 37 years. Then you could write a book about your experiments with CO2, POI, velocity, etc. 😉

      The truth is I am a little envious. It has been in the upper 80s and low 90s with incredibly high humidity for weeks now. I have a brand new air rifle and it is just too miserable to go outside and shoot it. I lube tuned it Saturday evening and went out on the porch to see if the firing cycle had been smoothed out and came in after about 10 quick shots and the sweat was just rolling off of me. That is just not fun. I am seriously thinking of the window slot idea.

    • GF1,

      Just get some of those little hand warmer packets ( open, shake and they heat up ) and lay them on the grip for a bit. That should work and you won’t be getting all light headed from hyper ventilating. 😉

    • Gunfun,

      Here’s an idea for you. Do you have a silica gel pack around somewhere? You know, the little “pillows” that come in vitamin bottles, or other similar items, to absorb moisture. Can you find one of those, or maybe two tiny ones, that would fit inside the grip alongside the CO2 cartridge? If so, throw a couple of those in the microwave long enough to warm them up — not too long, so that the covering burns, but long enough to where they might hold warmth for a few minutes if placed in a confined space. See what that would do for keeping the CO2 warmer.

      Jim M.

      • Jim M.
        That is a good idea. But there is not much extra room inside the co2 cartridge area on the Python, Brodax or m22. And the 1077 would be hard to get in the resivoir and get the cartridge peirce’s.

        Blowing the warm air with my breath is still the best I can think of. The most controllable too.

  4. I am now thinking the constant changing magnetic fields have something to do with this. At first thought you would think firing a non ferrous bullet would not be affected, but it would. Your common household electric power kwh meter has a aluminum rotor disk that is turned by the magnetic field created by electro magnets energized by the amount of power that passes through them to power your home. Makes me wonder if they have ever conducted any accuracy tests in the international space station. Doubt if they would have a 10 meter range, but even 5 meters would be cool. Imagine putting BB after BB in the same hole with your Red Ryder ! I have a app for my cell phone that measures the magnetic field and it is constantly changing values.

    • K7uqsshooter,

      You might want take some aluminum foil and line your hat. 😉

      Though that sounds like a very interesting experiment and I personally would really like to see them do such, I seriously doubt they would perform experiments with an “assault weapon” and very likely they would be concerned with something puncturing the hull or at least stray BBs floating around. Of course they could alter the magnetic fields inside the space station to propel the BBs out the air lock.

      A thought just occurred to me. They could mount the target on the long arm and hold it in a safe quadrant. They would have to use a specially adapted Red Ryder as the space suits would make it most clumsy to handle and the vacuum would boil off most lubricants.

      • Doesn’t the Red Ryder use air compression to work.
        No air in space so the Red Ryder would be out.
        You’d need a self contained PCP…or am I missing something?

        • Cowboystar Dad, looking at videos of the space station, the crews are not wearing breathing apparatus. I would imagine the interior of the space craft is pressurized much like a modern jet airliner, so we should have have atmosphere conditions much like earth, so there should be air for a Red Ryder to work. Since we are just going to punch holes in paper we could use a airsoft gun . I would leave that up to the airsoft guys to come up with a accurate gun . Ridgerunner, the foil helps me quit hearing those strange voices telling me to order another gun !

        • “In space, no one can hear you scream.”

          As I said, it would have to be specially adapted. Perhaps they could vent the methane gas from their space suits into the compression chamber. Then by adding a flint striker to the BB push rod they could obtain incredible velocities with no gravity or air friction to slow the projectile.

          Of course that would likely increase the recoil which could be problematic. Also they would not want to fire it inside the space station because of the high oxygen content of the atmosphere and the residual odor it would likely leave.

    • K7,

      I have thought of trying to fire bb’s through a flat, circular magnet that has a hole in it. I have some that about 4″ with a 1 1/2″ hole in them and are about 1/2″ thick. They are off of magnetic pans that are made for holding bolts and such. Would the bb’s pick up on the magnetic field and all go to the same hole? As the bb nears the magnet, would it be “guided” or “funneled” to all go in the same point?

      Or take 4 or more magnets that are “opposing” one another and mount those to a board with a hole in it.

      The 499 would be ideal for this as the accuracy is at least a 1/2″ at 24′.

      I just checked, I do not have any of those dish magnets. 🙁 Still, it would be interesting to play with.

  5. If damaging to a bullet’s base affects accuracy negatively, does that mean accuracy is better when using a pellet pusher?

    I hope Part 2 can help explain the relationship of head diameter and accuracy. Should we go for a tight fit or very tight fit?

    • Siraniko,

      I saw on another blog where the guy shot pellets with damaged skirts and the results were very surprising in that they were close in performance with the non damaged pellets.

      Now if you have a pellet pusher that reshapes the pellet skirt to the proper shape, it can only help as long as all pellets are to the proper depth in the barrel. There used to be a pellet seating tool you could buy that had a ball on the other end for reshaping the skirts on damaged pellets. I could see where that would be a handy tool to keep in your possibles bag.

      • RR,

        GF1 posted that link I believe. Also, when we did the LGU deal, he sent some 15.89’s as well. The scope and the gun made it fine but the pellets took quite the beating. Later, I sent him back 10 of the worst of the worst with bent skirts. He fired them “as sent” and the results were quite good if remember correctly. So, if the skirt is thin enough, it will reshape the OD when it is pushed in the breech and imperfections to the ID would be “blown out” when the blast of air hits it.

        So yea, maybe bent skirts are not the big deal we make of it sometimes.

  6. G’day BB,
    Just come across a SuperChrono from Steinert, using waves to detect velocity. I wonder how it would go with subsonic air rifles and shotguns.
    Cheers Bob

      • Same with scoring aircraft accuracy while shooting at ground targets.

        In pre 911 days, I used to enjoy watching the A10’s practicing at Camp Claiborne range. (From the meteorological trailer.)
        The aircraft would shoot at parachutes suspended between poles, and transducers would triangulate the projectiles path through the target area.

  7. B.B.,

    Thank you very much for doing this series. I am sure we all will be looking forwards to the next one(s?).

    Some of us are new to air guns and some are ” Ol’ Timers ” that have shot firearms and air guns their whole life. Some are well read and versed in all things gun/bullet related, while others are not. This series will give us “newbies” a good taste of things that been tried in the past.

    As for air guns, we all know of head and weight sorting. Some would consider these things to be an “extreme” effort to achieve perfection. Then,.. washing pellets,… secret lubes and oils, etc.

    With regards to Dr. Mann and the extremes he went through (and) the extremes some air gunners go through,….. one of the most fascinating and extreme was a “rig” that put pellets in a clear tube and passed air onto and around the pellet. Air gauges of all sorts were employed and readings of each pellet was taken. If I remember correctly,… pellet “wobble” could also be seen. I am pretty sure it was a guest blog, but maybe just a link.

    I think that would tie in well and create a “bridge” if you will,… that shows some of the extremes that we air gunners will go to in the never ending quest for that perfect group.

    Thanks again,…. Chris

  8. B.B.,

    On the above mentioned “rig” that sorted pellets by air flow,…… I found it!!!! 🙂

    It was a guest blog by FT Team USA and was published July, 10th., 2015. Jerry C. posted the link in his comment and is the 3rd. comment from the top. I would re-link it myself but I am as dumb as rock on that stuff. I do good to find my way back here each day! 😉


  9. BB,
    Do you know of any research done on the turbulence region behind the bucket (or pellet) as it travels and then leaves the barrel? For firearms, one might think that the bullet leaves fast enough to overcome the sudden expansion/pressure drop of the hot gas post-muzzle.
    And as for the weight balance of the projectile, I have to believe their’s merit to that. Every object has a natural frequency (thinking of comments on barrel vibration you wrote about a couple of years ago) and when that frequency becomes excited, chaos ensues. If the projectile is already excited at its natural frequency upon exiting the constraints of the barrel, then I would believe there should be eccentricity in its flight path.

    • javagonzo,

      I don’t know about any research, but I do know that high-speed videos reveal the gas from the gunpowder leaving the muzzle ahead of the bullet every time. So there is gas turbulence the bullet has to pass through just outside the muzzle.That’s both with black powder and smokeless.


    • The Cardew father and son team wrote two books:
      “Airgun from Trigger to Muzzle” (1976) and a revision, “Airgun from Trigger to Target” (1995). Their work was very technical, and experimentally showed how many factors affected the accuracy of airguns. I have seen some criticism of their scientific approach, but it seems very valuable to me. Web searches will reveal some of the work is now online. Those of us willing to dig in may find some good background.

  10. B.B.

    Thanks for this new series on accuracy. I’m eager to read your part about airguns. Having read today’s blog, I don’t feel so bad about my shot groups.

    By the way, I think I found a few errors in the blog missed by the spell check:

    “but bullets with damaged baes because very erratic”
    I think you meant, “but bullets with damaged bases became very erratic”

    “Damaging to a bullet’s base affects accuracy negatively.”
    I think you meant, “Damage to a bullet’s base affects accuracy negatively.”

  11. Siraniko– You are right. the watch glass is supported by a petri dish. The petri dish makes a perfect base to support the watch glass. The rim of the w glass is supported by the flange of the dish. The center (or apex) of the glass may or may not be in contact with the center of the dish. The whole thing is stable because of the flat bottom of the p dish. So, Dr. Mann used petri dishes and watch glasses to perform these tests. Ed

  12. B.B.,

    “A vise is the only way you can be certain the gun is completely out of human hands (true)” is a statement people say that I have some doubts about, specifically the word “only.” I consider your artillery hold to be, if it is relentlessly practiced by the shooter and consistently applied, a way of allowing the gun “to do its own thing.” If the gun is inherently accurate, it will bounce and recoil and hop and shimmy and everything else the same exact way every single time, taking the shooter largely out of the equation. If the gun moves the same way each time, well, it will group tightly (i.e. shoot accurately) if it is inherently accurate with that pellet. No?


    • Michael,

      You need to read that statement carefully. It’s the “out of human hands” part that is true. I never said it was the most accurate way to shoot a gun. In fact, I believe it is not, but that gets me into a lot of heated discussions. 😉


      • B.B.,

        Oh, I know that’s not how you feel. That’s why I carefully worded my comment, “a statement people say.” Those people do not include you or me. If a device could be designed that kept the air rifle pointed at the target but did so without impeding it’s movement as it goes through its shot cycle, essentially a device that provided an artillery hold, THAT might produce interesting results.


  13. Hope everyone will forgive a little off-topic post – a friend commented that the Olympic coverage was not very friendly to the shooting sports competitors (particularly the women). But I did see this interview last week with Ginny Thrasher. She won gold in 10M air rifle. An incredible accomplishment, shooting against former medalists and champions. This charming 19 year old woman from Virginia broke the world record. And this interview was the highlight of the games for me…

  14. B.B., et al,

    This is a very interesting topic. If airgun sports continue to gain in popularity, then it’s possible that a modern-day Dr. Mann could emerge to tackle the problem with 21st Century technology. There are so many dynamic variables here that the answer may never be truly, empirically found in the real world. Reminds me of Chaos Theory, which stated that the extended behavior of any complex system can’t be accurately predicted because of tiny errors in observational measurements that must be fed into the predictive model. These errors are compounded by the model’s calculations until it is useless in fairly short order. This theory enjoyed wide scientific popularity until it became inconvenient for the climate change people.
    But even if we never know the exact answer, we’ll still learn a lot of useful things along the way. Perhaps a curious young shooter will be inspired by your column to continue the quest.
    Thanks for tackling this sort of subject!


  15. Mr. Gaylord:
    So what I think you’re saying is
    when target shooting, even when trying to eliminate the human variable, shooting involves a fixed number of know variables, (barrel, bullet, air charge or powder etc) that interact in a unique manner with each shot to produce a random event which ultimately falls into a limited probability density function,(a/k/a the target bull).
    Got to love the statistics of target shooting. 🙂 🙂
    William Schooley
    Pistol & Rifle Coach
    Crew .357
    Chelsea, MI

  16. Accuracy, to an extent is subjective, this takes me back to the Webley that BB is testing at the moment, and the Airsporters etc that were hugely popular for the best part of a century here in the UK, as sporting rifles, and yet, you see the inch groups at 20 yards…and wonder how this can be?, indeed I look at the results from the Benjamin spring guns, the Hatsans and the many Chinese rifles and dismiss them as mere tin can busters.
    However, the nature of small pest hunting has changed, prior to around 1970 an inch was perfectly adequate, there were no real airgun optics, nor a need for them, you took your retriever or lurcher dog, and shot rabbits at only 50 to 60 feet away, relying on your hound to despatch a lot of the time, even power, up to a point wasn’t that critical, you simply had to be able to stop a rabbit. Most rat and pigeon shooting was done in and around barns with the shotgun used for corvids and pigeons in trees.
    Because of the size and population of this little island using firearms was never all that popular even when it wasn’t regulated, our pests are small and the risks are high.
    There’s been a sea change now though, 177 is the calibre of choice for longer ranged hunting and, unless you can drop a rabbit, squirrel, Crow or rat….absolutely…where it’s hit, you won’t get invited again, and are expected to shoot at the range you can do that…consistently.
    Thus, the requirements for accuracy from the equipment and your perception of your equipment’s accuracy have changed hugely, in 1953 wandering through the lanes with your dog at heel and your 22 Airsporter over your arm and a warm pocket of soft and slightly malformed pellets had you feeling very well equipped for a couple of dusk rabbits over some farm gates, whereas these days unless you can put a perfect pellet cleanly through the hippocampus with your silenced recoilless rifle at 50 yards you spend long range time working out at what distance you can!

  17. Off-topic warning:

    I’m a sucker for bedraggled puppies that follow me home and old, beat-up air guns that have been treated sadly by their previous owners. My current question relates to the latter.

    I lost my heart to a beat up old Diana Model 5 pistol I found online. I’m guessing it’s a 1960-ish production gun (interestingly, Diana doesn’t seem to put production dates on this pistol like they do on their rifles). No sense to it since I already own a 1980’s-ish Diana Model 5 in excellent condition. But the old one looked sad like it needed someone to save it.

    Of course, the first step with a new spring piston gun is to test in on the chrono to see what condition the innards might be in. In this case I needed to replace the breech seal first. When I got the seal there was also a washer that apparently goes in the bottom of the breech seal hole first with the rubber O-ring on top of it? Here’s the question: What purpose does the washer under the O-ring serve? How can I tell if there’s already a washer stuck in the bottom of the hole?

    Thanks for your patience with this question!

    St. Louis, MO

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