This is another little thing i did a while back. I had an extra barrel so no disassembly was required for this demo.
My B51 likes the CM and Baracudas but my 2240 gets finicky at all but the Baracudas past 15yrds. I couldn't for the life of me figure out why i couldn't get sighted in as quickly when it came to certain pellets. One day i disassembled my gun with a pell still in the barrel and this is what i found about pellet choices.
You can easily see the depth of each pellet when loaded in the barrel. The Silver Bear (below) is less than half way past the port hole. This allows air pressure to get around the head of the pellet before it moves forward and the skirt seals the barrel. The remaining air then has to propel the pellet while air is sealed between the head and skirt. My knowledge of physics tells me that this pocket of pressure creats an ill effect on the pellet upon exiting the barrel.
The Silver Arrow and Crow Mag below insert to about the same point and except for fps have pretty much the same performance in my 2240 within 15yrds. After that the CM holds more true. Except for the weight 17.13g and 18.21, respectively, i think they are about even.
The Baracuda has been my pellet of choice and now you and i both know why. When the transfer port is in place there's nothing getting pressure but the bottom of the pellet. At 21g it's really not a CO2 pell. Glad we don't have that problem.
The depth at which the pellet sits is directly related to the way the inner skirt is designed. CPHP having flat bottoms set deeper in the barrel which is why you get good accuracy and consistency. Instead of extending your probe try changing to a flatter bottom pellet. I don't think the light weight CPHP perform as well at higher fps especially with shorter barrels.