by Tom Gaylord
Writing as B.B. Pelletier

Part 1
Part 2

This report covers:

  • Must load from the front of the cartridge
  • Sizing pellets to fit into the mouth of the case
  • How deep is the pellet seated?
  • A lot of “stuff” to support the adaptor
  • The stuff
  • The test
  • Benchrest
  • Surprise!
  • Shot 4
  • Discussion

Today we look at the accuracy of the firearm pellet adaptor. This is what we have been interested in all along. In Part 2 we saw that the velocity was stable when the pellets were loaded deep inside the neck of the adaptor, but not when they sat proud. That generated several questions that I will address before I get to the test. Everything I do today was done with the .22-caliber JSB Exact Jumbo pellet.

Must load from the front of the cartridge

Several readers wondered what might happen if the pellet was pushed in from the rear of the cartridge, rather than loaded from the front. The dents at the base of the cartridge case shoulders prevent that from happening, though I expect you could push a pellet through if you used a lot of force.

Those dents are there to stop the pellet from falling into the case, but that engendered several more questions.

Sizing pellets to fit into the mouth of the case

I mentioned that I had to reduce the diameter of the pellet skirt before it would enter the case mouth. I did that by rolling the pellet between a steel plate and the hard top of my desk. That reduced the skirt diameter by several thousandths, which is all that was required. Chris USA asked to see a picture of that, so here it is.

sized pellet
The rolled (sized) pellet is on the right. You can see a flat spot around the base of the skirt where the diameter has been reduced, and also around the head..

How deep is the pellet seated?

A couple people asked me whether I pushed the pellet past the dents into the case. I said I did in the report, and they asked me to show them how deep the pellet actually was. Here is that picture.

seated pellet
This picture shows how deep the pellet is seated. Obviously the pellet’s skirt goes past the dents (there’s one on either side).

Then someone asked me to seat a pellet as deep as I normally would and then remove it, so they could see the skirt for themselves. So I did that next.

damaged pellet
The pellet on the right was seated to the normal depth, then removed.

At this point I was thinking that there is no way this adaptor can work, with that amount of damage to the pellet. But this blog isn’t just about what I think. It’s about what actually is, and the only way to find that out is to test it.

A lot of “stuff” to support the adaptor

I set up my shooting bench at 10 meters and brought out all the stuff I need to reload the adaptor. It is a pile, I can tell you! Let’s look.

reloading stuff
This is the stuff I used to load the adaptor.

The stuff

I needed pellets and primers, obviously. And something to push out the primers after I fired. I used one end of a cotton swab for that, and the other end I coated with Tune in a Tube grease to grease the o-ring in the base of the cartridge. That made the primers easy to install and remove. In the beginning I used my pocket knife to pry out the primer before greasing the o-ring. After I greased the o-ring the swab pressed it right out. I used the two coasters at the top of the picture to roll the pellet to size.

The test

I didn’t have much faith in this adaptor — perhaps I have mentioned that already. So my first shot was from 12 feet, and I just hoped to hit somewhere inside the pellet trap. My AR-15 has a Tasco 8-40 power scope mounted on it, so I dialed the power down to 8 and adjusted the sidewheel focus down to 10 yards. That gave me a fairly clear image of the target at 12 feet. Not knowing where the pellet would strike, I aimed at the center of the bull.

The first shot landed in line with the center of the bull and about 2.5-inches below the aim point. That was at 12 feet, so I knew the pellet would rise a little at 10 meters — if the adaptor and rifle proved to be accurate.


So I backed up to 10 meters and rested the rifle in a large sandbag. I drew an aim point on the target above the bull, figuring that if the adaptor was accurate that would put my shots into the black somewhere.

The first shot surprised me by going exactly where I thought it would — in line with the target center and at the bottom of the black. Maybe this thing really works?


The second shot went somewhere, but through the scope I could see no new holes in the target. Could it have gone to the same place as the first shot? If this was an accurate pellet rifle that is exactly where it would have gone, but through the scope I just could not see a second hole. So I walked down and looked closely — and there it was! The second pellet went to the same place as the first. I took a picture, in case the subsequent shots messed it up.

The second pellet didn’t want to seat, so I pushed the nose of the pellet down on the stone coaster to seat it. It went in the case much deeper than I had been loading, so I was ready to explain why it didn’t go to the same place — except it did!

target 1
There is the target. The cross above the bull is the aim point. The hole below the bull is the first shot — the sighter from 12 feet. And, in the black at 6 o-clock there are two pellet holes touching each other!

There are the two pellet holes.

deep seated pellet
When the second pellet refused to seat I pushed it down against the stone coaster and this is what happened. After seeing the results of the second shot, I decided to seat all pellets this way.

Well, after a result like that I was astounded! This was unlike anything I ever expected or have seen in testing. I loaded a third pellet and seated it the same way as shot two. The pellet went to the same hole in the target!

Shot 4

The fourth shot was different. I rolled the pellet a little harder than before and was able to seat it all the way in the adaptor with my thumb. When I shot, the pellet struck the target at 3 o’clock about an inch away from the previous 3 shots. Well, I thought, that was just due to the difference in the way the pellet was seated, so I decided to shoot 2 more shots and finish the group at the bottom.

The next shot went into the group at the bottom, but shot 6 (which would have been the fifth shot for the bottom group) went to the same place as shot 4. I ended up with 2 groups — one having 4 shots and the other having just 2.

The larger group measures 0.44-inches between centers. All 6 shots measure 1.265-inches between centers. That’s not too shabby!

final target
The large group of 4 shots at the bottom measures 0.44-inches between centers at 10 meters. The entire group measures 1.265-inches between centers.


I think there is probably a knack to loading this adaptor to get the most accuracy out of it. But I am impressed by just whet we see here.

Is this for you? Well, if you don’t own an air rifle and do own a .22 centerfire that’s accurate, this might be worth a look. It gives you a pellet rifle of medium power and accuracy. But consider this, besides the cost of the pellet you are also using a shotgun primer that costs about 3-4 centsl, depending on how many you buy. It would cost no more to shoot .22 CB caps in a .22 rifle and you would have more power. Or buy a Walther Terrus in .22 and just shoot the pellets.

And finally there is the time it takes to do everything. I am a patient guy when I need to be, but this process bores me. It takes me a full 3 minutes or longer to get the next pellet ready. That’s why there is just one target today and only 6 shots fired for record. I doubt most people would want to do this. The adaptors are $15 each, so 5 of them will cost you $75. I don’t think this is the way people will want to go.