mass vs velocity reguarding pellet weight?

mass vs velocity reguarding pellet weight?

Joined: October 3rd, 2011, 6:30 pm

June 25th, 2012, 3:16 am #1

Howdy!, Given a constant air pressure(force). Does a heavier pellet transmit more energy

downrange than a lighter pellet which proably has a faster velocity? I think the heavier

pellet will "drop " a bit more but in short distances does that matter? thanks for your help. don
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Joined: February 24th, 2006, 12:19 am

June 25th, 2012, 4:56 am #2

Long range, heavier projectiles tend to hold on to their energy better, as more mass means more momentum at a given velocity. Short range, it is probably less of an issue, but it really depends on what your initial velocities are. If you are shooting a 14.3 grain pellet at 900 fps and a 16 grainer at 600 fps, sure, the higher velocity will give you more energy. But if you are shooting the same two pellets mentioned above, the first at 900 fps, and the second at 825 fps, my money is on the heavier pellet, especially the further out you go. Of course, another thing you need to think about is what you are shooting at. If you are shooting paper at 10 meters, shoot what shoots most accurately. If you are shooting critters, shoot what it shoots most accurately with the best energy transfer at the range you plan on shooting at. That will often be the heavier pellet, but keep in mind, shape plays into it as well. A lighter, well built pellet may be a better option for hunting, depending on what your quarry is.
I hope this helps,
Chris
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Joined: April 20th, 2012, 2:33 am

June 25th, 2012, 2:03 pm #3

Howdy!, Given a constant air pressure(force). Does a heavier pellet transmit more energy

downrange than a lighter pellet which proably has a faster velocity? I think the heavier

pellet will "drop " a bit more but in short distances does that matter? thanks for your help. don
At close ranges, the lighter pellet is probably going faster giving it more energy. At longer ranges, the pellets slow down considerable making the mass the more determining factor. Remember the energy is the mass times the square of the velocity. The mass doesn't change, so it always supplies its part of the energy equation. If you go out to the point where the velocity is 1/2 of the muzzle velocity, you have 1/2 times 1/2 of the velocity supplying its part of the energy, so you only have 1/4 of the energy you have at the muzzle. The farther out you go, the more the pellet slows down, and the more pronounced this effect is.
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Joined: May 16th, 2012, 6:52 pm

June 25th, 2012, 2:55 pm #4

Howdy!, Given a constant air pressure(force). Does a heavier pellet transmit more energy

downrange than a lighter pellet which proably has a faster velocity? I think the heavier

pellet will "drop " a bit more but in short distances does that matter? thanks for your help. don
Some years ago, I did a simple experiment with my .177 Crosman Phantom. Using dog food cans filled with water at 20 yards, I shot Crosman Destroyers and Pointed pellets, in the 7g+ weight and 10g+ Beeman Kodiaks at the cans. The lighter 7g+ pellets made a water spout and went right through the cans, but did not knock the cans over. The heavier 10g+ pellets went through the cans, made the water spout, made much larger exit holes, and also blew the cans off of the log. In other words, even though the .177 Phantom probably shot the 10g+ pellets at a slightly slower fps than the lighter 7g+ pellets, the heavier pellet hit very much harder at the same 20 yard range. Continuing on with my .22 Disco using 14.3g Benjamin HPs, the cans get blown away every time, as expected, with yet a heavier pellet.
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Joined: April 24th, 2012, 12:56 am

June 25th, 2012, 9:41 pm #5

Howdy!, Given a constant air pressure(force). Does a heavier pellet transmit more energy

downrange than a lighter pellet which proably has a faster velocity? I think the heavier

pellet will "drop " a bit more but in short distances does that matter? thanks for your help. don
The trajectory of a pellet, and the velocity along the trajectory, can be calculated using Newton's Second Law: F=ma Force = mass * acceleration. Two additional pieces of information are needed: the initial velocity leaving the barrel and the drag force equation for the pellet. The derivation and resulting differential equation can be difficult to solve. But there are free software programs on the www that will solve the trajectory for you, and will answer the questions you're asking. I like Hawke Chairgun Pro.
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Joined: May 6th, 2010, 4:26 pm

June 26th, 2012, 1:11 pm #6

Howdy!, Given a constant air pressure(force). Does a heavier pellet transmit more energy

downrange than a lighter pellet which proably has a faster velocity? I think the heavier

pellet will "drop " a bit more but in short distances does that matter? thanks for your help. don
One very important factor is that in PCPs a heavier pellet generally will exit the muzzle with a higher energy level than a lighter pellet, with everything else exactly the same in the gun's settings. It is a function of the efficiency of the pellet/gun system in getting energy out of the air in the shot cycle, and the difference can be on the order of 10% or more, depending on the weight difference. As stated by others, the velocity of the heavier pellet will be lower, but it it is important to know that they will almost always have a higher level of foot pounds of energy than a lighter pellet even though the lighter pellet will be moving faster - lighter pellets are simply less efficient in PCPs (this is true in most pneumatics - however spring guns often go the opposite way).

After that, the the ballistic coefficient (BC) of the pellet impacts how well it retains the energy. As others have indicated, a heavier pellet generally has a higher BC, and thus retains energy better, than a lighter pellet - but that is not always the case as sometimes the BCs can be close, especially in the "mid-weight" range. But it usually is true when comparing extremes (like Baracudas to mid-weight pellets).

Thus heavier pellets will almost always start with more energy AND are will lose less energy on the way to the target. Bottom line - heavier pellets ina PCP will have more energy at the muzzle, and at every distance from the muzzle.

So if you know the ballistics, and where the pellet will hit, a heavier pellet will almost always deliver significantly more energy on target than a lighter one. But you need to know the BCs of the pellets to be sure at long distances.
Last edited by AlanMcD on June 26th, 2012, 2:57 pm, edited 1 time in total.
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