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Old July 10th, 2007, 02:49   #15
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Join Date: Jun 2002
Location: Toronto
There is a confusion in this conversation that requires clarity, not just for the original poster, but for some of the replies.


You are 100% correct. AT THE MUZZLE, a gun shooting 328fps with 0.20g BBs will shoot 1 Joule, and if you use 0.25g BBs, it will STILL output 1 Joule, albeit at 298fps.

The clarification: Velocity measurements are typically done AT THE MUZZLE.
CDN_Stalker hit the nail on the head. 100 feet away, a heavier BB will carry more energy through its trajectory. This is why heavier BBs are more stable in longer flight, especially in the wind. It carries more forward energy than a lighter BB. This is typically what is meant and understood when people say "I want to use a heavier BB so my opponent can feel my hits." At range, the target WILL take more energy from the BB than a lighter BB - only because the lighter BB has lost much of its energy in flight.

So why are there replies in this thread that contradict each other, including the above statement I just made about muzzle energies being the same?

There are two fairly different systems being discussed here:
1) "Constant" systems such as electric and spring powered guns
2) "Variable" systems such as gas powered guns.

The stipulation: The above theory ONLY applies under the rule of "constant" systems such as electric guns (that use electricity to crank a spring powered piston) and spring powered single-cocking guns (such as bolt action guns or cheaper springer guns.)
No matter how heavy the BB is, the spring will only compress so far, and the spring will always release at the same rate. The force of air leaving the nozzle, and the volume will ALWAYS be the same, regardless of BB weight. This is why AEGs and spring powered guns can have BB velocities calculated, as long as you know the muzzle energy.

So let's explain the contradicting posts:

The other system at discussion here, are "variable" systems, ie gas powered guns.

Gas, in itself, is not consistent. It expands at different rates, given different conditions and variables. At warmer temperatures, gas expands faster, colder temperatures, gas expands slower. That's pretty common knowledge.

However, there's more to it than that. Why are there users (such as mcguyver) who claim similar velocities, despite differing BB weights? Exactly as he stated when he started off his post: "Gun output is not always a constant." At least not with gas guns, they aren't, especially if different weight BBs are used. A major variable that affects the amount of gas outputted is the weight of the projectile being thrown.

Heavier projectiles accelerate slower. They require more energy to accelerate as fast as lighter projectiles. Due to this fact, heavier BBs stay in the barrel of a gun for a longer period of time than a lighter BB will, and because the BB has more time in the system, it has been subjected to more gas expansion time. By the time it leaves the muzzle, the gas would have had more expansion time than a lighter BB would. Not only does the gas have more expansion time, but the longer amount of time the BB is in the system has allowed the gas valve to stay open longer, and as a result, a GREATER volume of gas is expelled when using heavier BBs. It must be understood that almost all modern self-chambering gas guns these days do NOT shut off the gas valve until the BB has left the barrel! Greater expansion time + greater volume = greater energy expelled.

This knowledge, I believe, is important to know and understand. Players who are familiar with constant systems typically don't understand the variance in gas systems. To them, 1 Joule is one Joule, regardless of what gun you use. It's not true. Gas guns, WILL output more muzzle energy if you use a heavier BB! In this thread alone, mcguyver cites velocities that back this claim, as does CDN_Stalker, and I can as well if needed. I have 6 gas powered guns here that I have taken readings off of to back this claim, as have many other players in the past. I also have several different constant system guns (mostly AEGs and some springers) that back the theory that their energy is always constant.

For game safety reasons, players and game organizers SHOULD understand this knowledge that muzzle energies will differ at the muzzle, especially with gas guns. Otherwise, they could chronograph a gun with 0.20g BBs and be well within safe gaming limits, but the moment they drop in heavier BBs, they could potentially have a gun that could cause unnecessary hurt. I still think that imparting energy limits, rather than velocity limits is a more consistent and safer method of keeping players in check. Otherwise, players who know this difference can (and will) use this loophole to their advantage: test with light BB, use super heavy BB to shoot harder and cause more hurt.


To sum up, and answer the original question: Although heavier BBs have the same energy at the muzzle in some guns, there are other guns that have higher muzzle energies when using heavier BBs!
But despite that fact, no matter what kind of gun is used, YES, heavier BBs DO hit harder at range!

Last edited by ILLusion; July 10th, 2007 at 02:58..
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