RMAC 22 rifle
This is the actual rifle I’m testing. I won the lumber lottery with this one!

Part 1

History of airguns

This report covers:

  • “Many a slip…
  • Increasing your firearms education
  • Size matters!
  • A difference
  • Oily!
  • The barrel
  • Summary

Today we take a closer look at the .22 caliber breechloading black powder rifle once made by Rocky Mountain Arms Corporation (RMAC) of Utah.

“Many a slip…

… twixt the cup and the lip.” That’s another way of saying “Don’t count your chickens before they are hatched.” I had planned to start shooting the RMAC .22 rifle today, but I was careful to take my time while examining it this morning. I discovered that it is still full of oil from the factory. Oil and black powder don’t mix well.

I also wondered what I was going to shoot, since this rifle shoots a number 4 buckshot that is difficult to source anymore — at least in quantity. I was about to lament to you that my other unfired rifle came with a small bag of lead balls, when what to my wondering eyes should appear in this box but the same small bag of number 4  buckshot.

RMAC 22 loading tool bag
A collector wouldn’t do this, but I carefully removed the loading tool from the bag, so I can use it in this series.

BB RMAC balls
Once again, a collector wouldn’t open this package. But these are the only number 4 buckshot balls I have at present and there are things I need to know if I’m going to shoot this rifle.

BB RMAC balls and loader
There are two lead balls and the loader. Think those “balls” are spherical? Think again!

BB RMAC balls detail
Those “balls” are only spherical from a distance. This is what buckshot looks like up close.

Now, number 4 lead buckshot is nominally 0.24-inches in diameter. Well, that is in a perfect world and you will seldom if ever see a buckshot that is spherical. Look at the one on the right. You can see that one won’t measure the same all around. So, what do these balls measure?

BB RMAC balls measure
Well, measuring it that way I get 2.340-inches. Rotate the ball and get a different number.

The two balls I measured ranged from 0.231- to 0.239-inches in diameter. That’s pretty good, but not as close as swaged balls. The thing is — where do I find swaged balls, or even cast balls that size?

Increasing your firearms education

I’m going to seem to go off topic now, but really this is something you need to know, to follow this report. Cap and ball revolvers like the Colt 1860 Army are loaded by pouring black powder into each chamber of the cylinder, then ramming in a lead ball on top of that powder. 

The guy in the video you are about to see also puts a grease wad (a cardboard wad he has soaked in olive oil) down on top of the powder. If you are going to shoot the gun right away, that’s no problem. If you wait a day after loading, you could have some misfires, due to the powder getting fouled by the oil.

I show the film to show you something else. After he rams the ball into the chamber, there is sometimes a thin ring of lead that has to be removed. It was sheared off the ball when it was rammed in. That is intentional. It prevents the fire from one chamber from jumping over to the neighboring chambers, resulting in a chain fire (several chambers firing at the same time) that is both dangerous and often ruins the gun.

Black power is very prone to explode in the presence of fire. So Colt and others tapered the entrance to each cylinder chamber so the ball was squeezed (swaged being the correct term) down, often shearing a thin ring of lead in the process. That kept the ball tight over the powder so no fire could get around and ignite the chambers that weren’t being shot. Now some people will put lard or vegetable shortening over all the chambers after they are loaded, but I have found that that stuff just melts and makes the gun an oily mess. However, I do like the olive-oil soaked cardboard wad idea and may try it if I ever load another cap and ball revolver. I might even try it with this rifle!

Size matters!

The balls that guy in the film loaded into his revolver were very round. They had been swaged round and were within one or two thousandths of an inch all over — as long as they were handled carefully. As you can see by the picture above, number 4 buckshot is not that round. This matters if I want to shoot this rifle a lot. I’m going to need more balls — BUT they have to fit this rifle! And now you understand what I mean by the word “fit.”

BB RMAC ball fit
This is how a number 4 buckshot fits in the chamber of the RMAC rifle. It gets rammed into the chamber in the rotating breech by the loading tool.

The question is — where can I find pure lead balls that are close enough in size to work in this rifle? Well, I found them. A 25-pound bag of Remington number 4 buckshot cost me $117 plus change with tax and shipping. The price sure has risen in the past 10 years. I remember paying a quarter as much for a 25-pound bag of birdshot!

A difference

The 1860 Colt Army has a cylinder whose chambers swage down the balls when they are loaded. There might be a little of that going on with this rifle, but where it really swages the ball is when it shoots forward into the barrel. This is a single-shot, so there is no danger of a chain fire. And the ads said that the .24 caliber ball gets swaged down to .20 caliber when it enters the bore. We shall see.

Build a Custom Airgun

Oily!

When I looked at the parts that will touch the powder and caps I discovered they were all oily. So the gun had to come apart and be cleaned. Easy-peasy!

Bring the hammer to half-cock, press down on the thumb latch and rotate the breech 90 degrees to the left.  The cap cover that acts sort of like a hammer to pop the cap (remember — this rifle uses toy caps to ignite the black powder) slides right off the breech and there were at least 5 spare cap covers in the box. Hold down on the thumb latch and keep turning the breech to the left until the front of the breech faces the hammer (180 degrees) and the breech just lifts out of the receiver. Then cock the hammer fully and press the hammer extension (firing pin?) forward and it falls out of the receiver. Gotta go forward, though, because it’s too wide in front to go to the rear.

BB RMAC breech
When the breech is rotated 180 degrees it lifts right out. The nipple (where the fire from the toy cap passes through to the powder) is facing you.

BB RMAC cap cover
This is the cap cover that hits and explodes the caps when it’s struck by the “hammer extension” (firing pin?).

BB RMAC hammer extension
This hammer extension is struck by the hammer and it hits the back of the cap cover, which crushes the cap against the firing nipple, causing it to explode.

The barrel

Just for fun I peeked down the barrel and — OH, MY! It appeared filthy. It was probably just dirt attracted to the oil the factory put there but I cleaned it with solvent and cotton swabs anyway. I was concerned that since this rifle is supposed to really be a .20 caliber (that’s what their advertising literature said) that the cleaning rod wouldn’t fit, but it did. It was tight, but it did go all the way through.

Now, clean all the small parts with rubbing alcohol and dry them. After that the hammer extension is one place where a thin coat of lithium grease would work well. Then assemble the rifle.

Now that the gun is back together and now that I have a (more than) lifetime supply of ammo coming, I can shoot the rifle. Ironically, that’s what I set out to do at the start of this report, but all that other stuff got in the way. Well, I’ll shoot it next time. I’m not even going to explode a cap today because caps are corrosive and I would have to clean the entire gun after one shot.

Summary

You have now seen more deeply into the RMAC .22 breechloader than probably many people. Next time we will try to shoot it.