Pellets’ fit in the bore: Part 2
by B.B. Pelletier
Well, well! There’s lots of interest in this subject, and some of you have already made some observations of your own. Apparently, many people know that all pellets and bullets leak gas/air.
We left off with a discussion about thin-skirted pellets made from soft lead (which I often refer to as pure lead). Let’s shift to pellets with thicker skirts, and pellets made of hard lead. All Crosman pellets spring to mind when I mention hard lead. The Crosman Premier domed pellet in the cardboard box is still one of the best pellets on the market – BUT ONLY WHEN IT FITS THE BORE WELL. In the case of the Mendoza RM 2000, it is too loose at the breech, and the air is not sufficient to deform that hard lead skirt. For that rifle, the Premier is not the pellet to choose. That’s why I went with the Eley Wasp. That’s also the reason I used the Beeman Kodiak…to give you a pellet you can buy.
Crosman Premier skirt wall is thicker than the RWS Superpoint, plus it’s made of harder lead.
Kodiaks are fatter pellets, and they also have thicker skirts. So they fit well in larger bores, and they don’t deform easily. Premiers don’t deform easily either, but they are smaller, so you need to check the fit in the bore.
Not only is the Kodiak skirt thick at the end, it tapers to much thicker very quickly.
This is one reason why I don’t like repeating airguns. Guns with clips that have chambers smaller than the bore of the rifle allow the pellet to expand to that smaller size, then they enter the larger bore and rattle all the way through. If the clips have chambers larger than the bore, this isn’t a problem. There are things the manufacturers can do to correct this, with a choked barrel being one of the best. If they don’t do something, the rifle can never be accurate.
While this sounds like a terrible problem, most airguns don’t have it, so perhaps it’s more theoretical than real. I just like to load the pellet directly into the breech myself.
Why solid “pellets” cannot work in today’s airguns
A solid pellet must be exactly the diameter of the grooves to seal as much of the gases as possible, because pellets do not obturate. Big word, there. Obturate. It means to stop up or to close. In vintage blackpowder arms, lead bullets expand at their base when smacked by the force of the black powder exploding, and they obturate the bore when they do. In modern guns, smokeless gunpowder doesn’t burn fast enough to obturate a lead bullet as well as black powder, so the bullets must seal the bore with the diameter of their bodies. Airguns do not obturate bullets or solid pellets at all.
Because pellets do not obturate, the hole at the base of this piledriver pellet cannot cause the thick skirt to expand. This pellet must either fit the bore exactly or your thumb becomes a short starter! They are next to impossible to load in most breechloading air rifles.
The makers of solid pellets have to make their pellets to a certain diameter, then hope that the barrels they will be used in will have groove diameters close to the same size. They rarely do! Even different barrels of the same caliber from the same premium maker, such as Lothar Walther, will vary by several ten-thousandths of an inch in groove diameter, because the tolerance depends on the spring rate (rebound rate) of the steel in the barrels and the speed at which the rifling button is pulled or pushed through. Therefore, it’s virtually impossible for a solid pellet to fit the barrel of a gun, except by chance. When it doesn’t fit exactly, it becomes very hard to force through!
Shooters who shoot muzzleloaders use a wooden dowel, called a short starter, to hammer the bullet through the rifling and bore for the first few inches. This is best done with a single smack of the hand, but anyone who has shot muzzleloaders very long will tell you it doesn’t always work the way it is supposed to.
Well, when you try to load a solid pellet into the bore of an air rifle, your thumb has to be the short starter. After five pellets, you give up because of a painful thumb – that is, if you make it that far! If you own a rifle with a cylinder like an AR6, you just drop the solid pellets into the chambers of the cylinder, assuming they fit, and you’re done! The rifle’s air will do the work of sizing the pellet and engraving the rifling for you.
What about diabolo pellets that don’t seat in the barrel?
Your problem here is similar to the one of using a solid pellet. Some diabolos, such as Eun Jins, are very fat and don’t fit well into the bore of the gun. But look what kind of airguns they were designed for – the Korean guns! And most of them either have a cylinder or a linear magazine. The shooter never tries to force the pellet into the barrel. When you try to use them in an RWS Diana 34 Panther, they surprise you by being difficult to chamber. That makes them the wrong pellets for that rifle, in my book.
What about other pellets that do go in the barrel but their skirts stick out? If the gun is a breakbarrel or any sort of spring gun, I just shoot them anyway. However, if you open the barrel after closing it, you’ll often see that the pellet skirt has been smashed on one side. Don’t expect good accuracy from that pellet.
If your rifle is an AirForce gun, you run the risk of jamming the valve open and exhausting all the air in the tank! AirForce guns must have their pellets seated at least flush with the breech to function properly. Otherwise, they can mash a skirt to one side over the breech, locking it in place and causing a stoppage in the breech that holds the firing valve open. The .22 Condor is powerful enough to overcome this, but the .177 Condor is known for it. So, seat those pellets deep!
Does oiling pellets help seal them?
Let’s be clear – I’m not sure we need to seal pellets any better than they are sealed through normal handling. That said, would oiling them help? I don’t know, but I think not. I think the air passageways around the pellet are so large the oil will be blown off by the force of the air. Also, every time I have compared oiled pellets to dry, the oiled ones were slightly slower. But, again, I don’t know.
What should you look for?
This is not an exercise where micrometers are needed. Accuracy is the best way of knowing if a pellet fits well in the bore of a gun. Also, pay attention to how the gun behaves – especially if it’s a springer. Springers are temperamental about the pellets they prefer and will tell you with excess vibration, recoil and detonations when things aren’t right. Pay attention to how the pellet fits in the breech. These are the things that pay off downrange.