PELLET DIMENSIONS
Written by: Der Luftmeister
Some time ago, I conducted some accuracy tests with a Daisy 22X multi-pump rifle. That model is a 22 caliber wood and metal rifle of modest power that has a well shaped stock and forearm. I had mounted a 3-12X AO airgun scope and was getting groups that averaged around 0.23 inch at 10 yards. In fact, I was well pleased with this performance. Then, without warning, the groups started measuring about three times this size. What had happened? I had changed to a different type of pellet.
The pellets that gave the small groups were the inexpensive pointed Daisy Max Speed. The bad groups were obtained with Crosman Premier, wadcutter, and pointed styles. Being curious, I continued to shoot and even tried several other types of pellets. Some grouped like the Daisy variety, some grouped poorly like the Crosman types, and some were in between. What did these observations mean?
Not all pellets are created equal. They differ in weight and point design as any air gunner knows. If you are familiar with the history of Crosman airguns, you probably know that several classic models are repeaters. The outstanding Crosman 600 pistol and Model 400 rifle come to mind although there are others. These models utilize an inline magazine to hold pellets. The pellets are pushed forward by a spring-loaded plunger so that each pellet is held with the nose pressed against the skirt of the pellet in front. If pellets having rounded or pointed noses are loaded in the magazine of these guns they do not feed properly. Moreover, if the skirts are made very thin and soft (as some are), there is a good chance that the pellets may be deformed enough to prevent proper feeding. Consequently, Crosman pellets have traditionally been produced with skirts that have thicker walls than most others.
It has also been my observation that Crosman pellets seem to be constructed of a harder alloy than are most others. Certainly they are made with shallow cavities and very sturdy nose sections. The result is that they give excellent penetration with minimal deformation.
While searching for some way to rationalize the accuracy results that I had obtained, it eventually dawned on me to take a look at pellet measurements. What I found was that in 22 caliber, the Crosman pellets have an average head diameter of 0.216 inch while the skirt averages about 0.222 inch in diameter. On the other hand, the Daisy Max Speed has an average head diameter of 0.215 inch, but the skirt averages around 0.226 inch. It is reasonable to assume (whether rightly or wrongly) that the diameter of the Crosman pellets might be kept on the small side so they would feed reliably through magazine rifles and pistols and enter the chamber easily.
Well, at this point I knew that the larger Daisy pellet shot well while the smaller Crosman pellets did not, at least in this particular rifle. What about other pellets? Having measured a great many types, it was easy to select some others of similar dimensions. Gamo pellets are virtually identical in dimensions to the Daisy variety so I tried Gamo Master Points in the rifle. Sure enough, the group size was almost the same as when the Daisy pellets were fired, and the groups averaged 0.24 inch. Groups with the Meisterkugeln, which has a skirt diameter of 0.225 inch, gave an average size of 0.28 inch.
The tests described were carried out in a cursory fashion, and I need to do a lot more work to make sure that the effects seen are reproducible. However, it is well known that airguns are finicky about the type of projectile used. I am not ready to say definitively that the skirt diameter is the critical factor, but for what ever reason, my Daisy 22X has definite preferences. Among rimfire shooters, it is well known that chamber dimensions vary considerably between rifles, and that is one of the reasons why specific types of ammunition shoot better in certain rifles. Perhaps the skirt diameter is a measurement that is critical to accuracy in certain air rifles.
Airgun shooting is primarily about accuracy. When dispatching pests, I normally like to use specific types of pellets because of their performance. However, even in that case I reach a compromise between pellet design and accuracy. If you do not hit the target, penetration or expansion makes little difference. If your airgun is not shooting quite up to par, it may be time to try some different pellets, especially ones with different dimensions. Serious air gunners know this of course, and they select ammunition carefully.
Until next time, stay pumped.
Some time ago, I conducted some accuracy tests with a Daisy 22X multi-pump rifle. That model is a 22 caliber wood and metal rifle of modest power that has a well shaped stock and forearm. I had mounted a 3-12X AO airgun scope and was getting groups that averaged around 0.23 inch at 10 yards. In fact, I was well pleased with this performance. Then, without warning, the groups started measuring about three times this size. What had happened? I had changed to a different type of pellet.
The pellets that gave the small groups were the inexpensive pointed Daisy Max Speed. The bad groups were obtained with Crosman Premier, wadcutter, and pointed styles. Being curious, I continued to shoot and even tried several other types of pellets. Some grouped like the Daisy variety, some grouped poorly like the Crosman types, and some were in between. What did these observations mean?
Not all pellets are created equal. They differ in weight and point design as any air gunner knows. If you are familiar with the history of Crosman airguns, you probably know that several classic models are repeaters. The outstanding Crosman 600 pistol and Model 400 rifle come to mind although there are others. These models utilize an inline magazine to hold pellets. The pellets are pushed forward by a spring-loaded plunger so that each pellet is held with the nose pressed against the skirt of the pellet in front. If pellets having rounded or pointed noses are loaded in the magazine of these guns they do not feed properly. Moreover, if the skirts are made very thin and soft (as some are), there is a good chance that the pellets may be deformed enough to prevent proper feeding. Consequently, Crosman pellets have traditionally been produced with skirts that have thicker walls than most others.
It has also been my observation that Crosman pellets seem to be constructed of a harder alloy than are most others. Certainly they are made with shallow cavities and very sturdy nose sections. The result is that they give excellent penetration with minimal deformation.
While searching for some way to rationalize the accuracy results that I had obtained, it eventually dawned on me to take a look at pellet measurements. What I found was that in 22 caliber, the Crosman pellets have an average head diameter of 0.216 inch while the skirt averages about 0.222 inch in diameter. On the other hand, the Daisy Max Speed has an average head diameter of 0.215 inch, but the skirt averages around 0.226 inch. It is reasonable to assume (whether rightly or wrongly) that the diameter of the Crosman pellets might be kept on the small side so they would feed reliably through magazine rifles and pistols and enter the chamber easily.
Well, at this point I knew that the larger Daisy pellet shot well while the smaller Crosman pellets did not, at least in this particular rifle. What about other pellets? Having measured a great many types, it was easy to select some others of similar dimensions. Gamo pellets are virtually identical in dimensions to the Daisy variety so I tried Gamo Master Points in the rifle. Sure enough, the group size was almost the same as when the Daisy pellets were fired, and the groups averaged 0.24 inch. Groups with the Meisterkugeln, which has a skirt diameter of 0.225 inch, gave an average size of 0.28 inch.
The tests described were carried out in a cursory fashion, and I need to do a lot more work to make sure that the effects seen are reproducible. However, it is well known that airguns are finicky about the type of projectile used. I am not ready to say definitively that the skirt diameter is the critical factor, but for what ever reason, my Daisy 22X has definite preferences. Among rimfire shooters, it is well known that chamber dimensions vary considerably between rifles, and that is one of the reasons why specific types of ammunition shoot better in certain rifles. Perhaps the skirt diameter is a measurement that is critical to accuracy in certain air rifles.
Airgun shooting is primarily about accuracy. When dispatching pests, I normally like to use specific types of pellets because of their performance. However, even in that case I reach a compromise between pellet design and accuracy. If you do not hit the target, penetration or expansion makes little difference. If your airgun is not shooting quite up to par, it may be time to try some different pellets, especially ones with different dimensions. Serious air gunners know this of course, and they select ammunition carefully.
Until next time, stay pumped.
posted by Randy Mitchell at
9:11 AM
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