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Ammo Firearm pellet adaptor: Part 1

Firearm pellet adaptor: Part 1

by Tom Gaylord
Writing as B.B. Pelletier

This report covers:

  • On a dare
  • The adaptor
  • Priming
  • Is it dangerous?
  • Loading the pellet
  • Discharge sound
  • Cost
  • Legality
  • Conclusions

I love it when I’m wrong! I try to be correct in my reporting, but sometimes I hit the wall and splatter all over the place. Today might be the start of one such time. I am reporting on an adaptor I bought to shoot pellets in a .223 Remington centerfire rifle, using the power of number 209 shotgun primers.

On a dare

My late wife, Edith, used to keep me straight by periodically challenging me. Whenever I said something that didn’t sound quite right, she invited me to put my money where my mouth iwa. She learned very quickly that I knew what I was talking about in the field of guns most of the time, but every once in awhile I was off the track. She learned to spot those times and she would call me on them.

She isn’t around to do that anymore, but apparently I got so used to it that I now call myself out! That happened the other day when I was talking about the adaptors that allow pellets to be loaded and shot in firearms. I said many things in my report that would not pass muster in the past, so I decided to dare myself to try pellet adaptors once again. I bought a .223 Remington adaptor to load into my AR-15. We all know that rifle is deadly accurate — putting 10 shots into a little as 3/8-inches at 100 yards. It ought to serve as a good test platform.

The adaptor

Okay, the adaptor is real high-tech (not). It’s a .223 case that’s been drilled out at the base to receive a number 209 shotgun shell primer. An o-ring inside the base holds the primer tight. The neck of the case has been punched on opposite sides to keep the pellet from falling into the case at loading.

The pellet adaptor has two “precision” divots punched into opposite sides of the base of the neck, to prevent pellets from dropping into the larger portion of the case, where they would be difficult to remove.

adaptor base
At the base of the adaptor the primer hole has been drilled out to accept a number 209 shotgun primer. An o-ring inside holds the primer tight. A fired primer is shown next to the adaptor.


The adaptor must be primed with a shotgun primer. The primer is simply put into the hole in the base of the adaptor and pressed in with your thumb. At first I thought it would not go, but eventually I discovered the right amount of force to use and the primer slid home. For as simple as it is, it really works quite well.

adaptor primed
The primer is pressed into the adaptor by thumb pressure. As you can see, there is a lot of primer to go inside.

To remove the primer after it has been fired, a cotton swab through the case mouth works well. Not only does it press out the spent primer, it also wipes carbon deposits from the case mouth.

Is it dangerous?

Is pressing a primer into a case with your thumb dangerous? You know that primers are detonated by impact and pressure. So, is it dangerous? Not really. Your thumb spreads out the force to the entire surface of the primer, where a firing pin strikes deeply in one one tiny spot. Al;so that o-ring makes loading a lot easier.  It does take a little courage at first, but after you have done it a few times it becomes routine.

Loading the pellet

To load the pellet you press it into the case mouth, tail-first. It isn’t easy. It’s like trying to herd a cat! I found that some pellets like Wasps just don’t want to go in. Their skirts are flared out too wide to enter the case mouth. But I was able to load a JSB Exact Jumbo and an Air Arms dome. Neither is easy, but with persistence they do go in. So far those are the only two pellets I’ve tried because I was just trying to become familiar with how the adaptor worked. I will try a range of weights in the velocity test.

adaptor loaded
Sorry it’s a little blurry, but the background is exaggerating things. The JSB Exact Jumbo dome is pressed in as far as it will go. The skirt is sitting on those divots you see in the first picture.

Discharge sound

Here is where I admit I was wrong. The ad copy says this adaptor sounds like a spring-piston air rifle firing. All my past pellet adaptor experience was with handguns that are very loud. I braced myself for the loud bang in my office and was pleasantly surprised by the quiet pop. It was about the same as a RWS Diana 34!

My AR-15 has a 24-inch barrel, so it’s possible that a shorter barrel may make more noise. But as it stands, this adaptor is very quiet. Backyard in the suburbs quiet! Now I am intrigued, for a number 209 shotgun primer has a lot of oomph. This adaptor could allow us to reload our own CB caps. If it is also accurate, then it’s worth consideration.


The adaptor costs $15. Primers cost around 4 cents apiece, so each shot costs that plus the cost of the pellet. It’s more expensive than just shooting a pellet and even more than shooting with CO2, but less than the cost of .22 rimfire ammo. Plus it is as quiet as a rimfire shot through a silencer.


But when you use this adaptor you are still discharging a firearm — not an airgun. If you were hauled into court for shooting this they could charge you with a firearm violation, because the pellet is propelled by means of a chemical explosion. Add to that the fact that you are shooting it in a firearm and it’s clearly not a way to circumvent the law.


I have a lot to test. The ad for the adaptor had a review that said the user was getting groups the size of a nickel at 20 yards. We’ll see about that. I still have a hard time believing this adaptor can be that accurate, given the difference in bore diameters of a .22-caliber pellet rifle and a .22 centerfire.

If it is accurate, though, it will be the first pellet adaptor I have seen that is. We shall see.

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.

39 thoughts on “Firearm pellet adaptor: Part 1”

  1. Hi

    Years before I bought a PCP .22 I had reasonable success with loading .22 pellets into .22 hornet cases, the long case neck made this easily achievable compared to the .223 cases. It worked well against pigeons and smaller pest birds in a single shot CBC rifle.


  2. BB,
    Sure looks like that protruding primer would mess with headspace. Does it actually protrude or has it been compensated for when the case was drilled out?
    I take it there is not enough recoil to cycle the bolt any …

  3. I made some similar to this many years ago just for grins, but never thought of the oring.
    Also, I ran the case through the sizer die without the expander ball.

    Then drilled out the case to take the 209 primer.

    I would drop a pellet in from the rear, and seat it in the neck with a small phillips head screwdriver, then press in a primer.

    Be careful of shooting many of these indoors, I an mot really a worry wart,
    but SOME primers MAY contain lead styphnate.

    I have reloaded for many years, and as a kid, walked around with a few lead pellets in my mouth while hunting.
    and I ain’t dead yet, but some people don’t like to take chances..

    I am eager to see how they chrono, when I did it, it was long before I had a chrono.

    • Pretty much all primers use lead styphnate, unless you go out of your way to find lead free ones.

      Death is by far not the worst outcome of chronic lead poisoning.

      Shooting it once indoors is thing, hundreds of times a day another.

      Not to mention what this would do to the value of your home, if you ever had to sell.

    • Riki,

      BB neglected to provide a link to his AR-15 build and testing. Try this.


      The type of accuracy that he is referring to would be quite miraculous with factory ammo, no matter what you were shooting it in. There are just too many variables in the mass production of ammunition for that to be achievable.

    • Riki,

      Yes. In fact I always load the AR singly, because the target cartridges I reload are too long for the magazines.

      Factory ammo in my AR is good for 10 in 2 inches at 100 yards.

      I hope to put 10 into a half-inch at 10 meters. That would be good. Even an inch would be acceptable. Experience tells me I won’t see 2 inches for 10.


  4. Interesting. Let us see how this plays out.

    Actually, this is a novelty that has my curiosity. I myself would not bother, but I am glad that a friend of mine has decided to give it a try and let me know how it does. 😉

    • Docteur Ralph,

      I have no urge to drop any powder into the case. I have been a reloader for over 50 years and experience has taught me what works and what doesn’t. It would take me several days to explain al, that means.

      I’m interested in this only to show how it works to my readers. I don’t think this is the way to go, or a good idea. But I’m also the guy who doesn’t like the magnum airguns, either. I’ve said many things about primer-powered pellets. Now we will see whether I was right to say them.


  5. B.B.
    I don’t think it would be accurate, but I bet a .22 lead round ball would be easier to load. If accurate, I might would want to try one, but I’d prefer it in a single shot rifle. Just me. Thanks for the review


  6. BB
    When you mentioned this I had doubts about it. Especially the pellet fit to the firearm barrel. Twist rate and velocity and all that other stuff.

    But seeing the cartridge or adapter I should say it seems it might just work. The primer looks like it should have a decent charge when fired. And I should mention I’m surprised it’s that quiet.

    But I just wonder if maybe the primer blast will have enough power to flare the skirt of the pellet and possibly engage the barrels rifling. Just maybe the pellet could be accurate out of the firearm barrel.

    I did that test yesterday on flaring the skirts on some pellets and tryed them in a springer and a my Maximus and .25 Marauder. The lower powered springer seen a benefit in accuracy. The higher powered pcp’s seen no difference in accuracy.

    Have you ever tryed that test before by flaring the skirts for a spring gun to help seal the skirt to the barrel? And I don’t mean deep seating the pellet. That’s something different.

      • BB
        I’m wondering if less accurate springers benefit from flared skirts more than a accurate springer.

        I mentioned yesterday to Chris to see if it helped his LGU and Tx. And Buldawg is going to try it in some of his springers to see what happens today.

        It did for sure help the TechForce 99 I tryed it in yesterday. But anyway just wondered if you tryed it.

        • GF

          Run it over the chrono .
          See if that springer has different velocity and different velocity spreads between the pellets that have been flared and the ones that have not .
          You might find your answer there .


          • TT
            I will try that today. And I think that’s part of it. A more consistent seal and velocity.

            The other thing I seen though from shooing into a phone book yesterday at 50 yards and recovering the pellets. Was that of course the heads were distorted. So really couldn’t see if any rifling marks on the heads. But here’s what is making me think flaring the skirts is helping accuracy.

            I shot and recovered 3 unflared pellets shot at different places on the phone book and recovered the pellets. Then did the same with 3 pellets I flared with the cap of my Bic ink pen. Those pellets showed rifling marks in the skirt. The unflared pellets showed no rifling marks in the skirt.

            So I believe in that particular gun that the head size of the pellet is not the correct size for the TechForce 99 barrel. I think that the flared skirts are actually sealing to the barrel rifling and acting like a pellet with the correct head size does in a barrel. In other words the skirt is engaging the rifling and giving the correct fit. And it’s improving accuracy like the right head size does when you sort pellet head sizes and separate and shoot the pellet that fits the barrel the best.

            All I can say is try flaring some skirts of pellets and try them in different guns and see what happens. Might get good results or same results depending on how well that pellet head first the barrel already.

              • TT
                Yep no rifling marks on the skirts if I don’t flare the skirts first.

                The head of the pellet verily has any drag on the pellet when I load it. I can feel the head contact just a bit harder almost right when the back of of the pellet gets flush to the barrel of a unflared pellet.

                When I flare the pellet. Then I can feel the skirt engage before I feel anything on the head of the pellet.

                So I guess I got one of those Chinese barrels that are on the lower totum pole of quality.

                But remember that I now got a more accurate gun shooting the pellets with flared skirts. So that seems to me that flaring the skirts is a good little trick for guns that don’t have adequate barrel sizing or pellet sizing to the barrel. Like I said it helped the 99 acurracy wise.

          • BB
            Maybe you can try a quick little test on a few guns with flared and unflared pellets and see what you come up with.

            No blog or anything just see what you get and make a comment here since this is kind of a different test your doing with the adapter than the normal testing you usually do.

  7. I had one of these adapters that I used in my T/C Contender with an 18″ bbl back in the ’90s. I got the idea from a friend who worked in my favorite sporting goods store. He placed a target on his TV so he could target practice while watching TV!

    Anyway, I gave up using it for two reasons: it wasn’t all that accurate, and the 209 primers left quite a bit of residue in the barrel. So i found it was easier, less expensive and quieter to use my airguns instead.

    I’ll be interested to see what velocities and accuracy you get from your tests.

    Joe on Maui

  8. B.B.,

    I have to think that the weight of the AR-15 provides the answer to my question, but it must be asked nevertheless. Recoil? (Stop snickering!) :^)

    How much smoke is expelled compared, say, to a detonating springer?


  9. Hello! I’m new to this,leaving a comment on Pyramyd AIR,I very much enjoy following along reading and learning about a type of shooting I had not done in many years.I have had two major back surgeries in the past eight months,I needed a to shoot a gun again.Limited to a wheelchair/walker a pellet gun I could shoot indoors was the answer! I am very familiar with firearms,sporting guns mostly,I have been hunting and shooting my entire life,over fifty years.I started with a Ruger Air Hawk in .177 caliber a few months ago.I’m starting to get a feel for this rifle after trying quite a few different pellets.A solid set of scope mounts,quality scope makes a difference if you desire,I do.After a long wait,I received my Diana K98 .22cal a couple of weeks ago,whew!did I get “the belle of the ball”I put three Beeman Silver Bears in one hole at 10yrds.I must confess,I hotrodded my K98 w/one piece medium mount and a 3x9x40 scope.Thanks for reading!

  10. B.B. Thank you for your reply! I live in the wilds of upstate N.Y.S. 1/8 of a mile from a D.E.P.Water Supply Resivor for N.Y.C.,Thousands of acres of state and private land surrounds me.I live in a mobile home stuck into the side of a mountain.Deer,bears eagles coyotes,bobcats,turkeys,squirrels,critters of all kinds live around me!I love it :-)!I I’ll be waiting,keeping my trigger finger loose and ready,waiting for more good stuff from Pyramyd AIR,you all may or not hear from me often but my attention is still here!-Toto

  11. There is a Company that make “Real” Adaptors
    Check-out Convert-a-Pell at: convert-a-pell.com
    22 cal Centerfire Rifles:
    “The Convert-a-Pell .22 Centerfire kit enables you to shoot .22 caliber pellets through your .22 Centerfire rifle or pistol, utilizing a patented “O”-ringed primer pocket that assures easy primer insertion and ejection. Calibers available include .221 Fireball, .222, .223, .225 WIN, .22-250, and .220 Swift, all machined to accept a .209 shotshell primer, and .22 Hornet, machined to accept a standard large rifle primer. Each Convert-a-Pell .22 Centerfire kit contains four cartridges. Trajectory of the Convert-a-Pell .22 Centerfire kit will average 2″ low with exceptional groups at 20-60 feet and beyond.”

    Or for Centerfire Pistols or Revolvers:
    “The Deluxe Rifled Model Covert-A-Pell kit has a rifled brass adaptor tube and six cartridges. This kit is available in standard barrel lengths from 1″ to 8-3/8″, in the following calibers: .380, 9mm., .38 Special, .357 Mag., .44 Mag., .45 ACP, and .45 LC. Trajectory of the Deluxe Rifled kit will average around 2″ low of aim point with groups of 1″ or less at 15-20 feet.”

      • BB
        I don’t own a 22 Cal, Centerfire Rifle, so I can’t give any type of “Range Report” on any of their 22 Adapters
        But I do own and shoot two of their .357 Revolver Kits
        They are a great tool for training on your Double Action Trigger Pull
        Fun and quite accurate at 10(+/-) yrds
        Looking to get Kits for my 44mags and maybe a 9mm one day
        I’ve asked, and Rodger said he may look into 40cal or even 10mm Pistol Kits

        Have a Safe New Year, Den S

  12. I have an original Paul 410 in working condition. The piece itself is in nice condition and would like to sell it. It was bought out of an estate so I don’t know a lot about it. This is the first time it has been offered for sale. I’m looking to get $700 or reasonable offer for the air rifle. Please contact me through email if you have any interest or for further information or photos of the piece. Blant100@yahoo.com I am located in Mesa in AZ. Thank you.

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