Fps Downgraded

[Mad Dog]

Thanks a lot to have enlightened me on the subject. I'd advise perhaps creating a document on the topic for the newbie area as it's not really covered, and i think it's a rather essential part of choosing a gun, since it would be sad to have someone purchase a gun that he can't use in some games.

[Flatlander]

Originally Posted by The Saint

FPS limit is something of a misnomer, it's really a muzzle energy limit.

The AEG itself always outputs a fixed amount of energy...

Neat FYI, I remember CND_Stalker posting up his fps results using different weights and I was bored so I converted them all to energy on excel. There was only maybe 10 readings per weight but the trend was clear - the enegy increased slightly as you increased the weight of the BB used. So to be a stickler at games you should really chrono using all .20's, energy, or an velocity conversion from the limits set at .20's.:banghead:

[Bissa]

Originally Posted by Flatlander

Neat FYI, I remember CND_Stalker posting up his fps results using different weights and I was bored so I converted them all to energy on excel. There was only maybe 10 readings per weight but the trend was clear - the enegy increased slightly as you increased the weight of the BB used. So to be a stickler at games you should really chrono using all .20's, energy, or an velocity conversion from the limits set at .20's.:banghead:

Now that I think of it that would make sense. because since the BB is travelling slower it spends more time being effected by the pressure build-up in the barrel.

[Milgeek]

Thanks for a very interesting post... Despite my ignorance I've tried to follow along, so can I recap?

BB weight can reduce FPS but increase energy?

Therefore a site should specify BB weight in it's limits, and also check energy?

Hope I understood that correctly.

[Nova316]

bb weight can reduce fps but the energy remains the same.
If u shoot say a 400fps 0.20gram bb
and switch over to .30gram bb your fps will drop to 300
but the energy of the bb in both cases will be the same

Thats why when you chrono at a game u use .20 grams

[Hectic]

Originally Posted by Cheesevillage

IIRC heavier BBs make no difference. Its not FPS we worry about its total energy.

Food for thought
.36g BB @ 800FPS would carry alot of energy

J=[M(V*2)]/2000

so if my math is correct it's 10.72J that would hurt thats for sure.


The max FPS is usualy determined with .2g bb's

EDIT never mind I'm too slow

[ShelledPants]

Originally Posted by Nova316

bb weight can reduce fps but the energy remains the same.
If u shoot say a 400fps 0.20gram bb
and switch over to .30gram bb your fps will drop to 300
but the energy of the bb in both cases will be the same

Thats why when you chrono at a game u use .20 grams

To expand on this;

The bb's energy on exiting the barrel will be the same, but at 100 feet, a heavier bb will have lost less energy than a lighter bb.

So heavier bb's travel slower, but with less wasted energy, coupled with hop up: a longer, and straighter flight path.

[m102404]

People feel heavier bbs at extended ranges more distinctly than they feel lighter bbs at the same range.

0.25/0.28/0.30 will result in a much more predictable flight path compared to 0.20 bbs.

Any maximum range that you give up by using heavier bbs you gain in increased effective range. You might be able to shoot a little further with lighter bbs...but, % wise, you won't hit what you're aiming at out at your maximum range with light bbs. This may not be completely accurate, but it should convey the idea. Spread your arms out as far as possible...that's the shot pattern at max range with light bbs. Now imaging moving 15ft closer to the shooter and put your hand shoulder width apart...that's the shot pattern with heavier bbs. If you were the shooter...which would you want?

At a couple of the games this year, the field organizers asked each player to bring their rifle and an empty magazine to the chrono when they registered for the game. They were given a couple of 0.20g bbs and their FPS and rifle type was noted on their sign up sheet. This may not happen at every skirmish and paintball-field game...but it's very effective for ensuring that everyone knows what they're shooting at.

[Flatlander]

Well here's some useless stats I just cooked up which are hard to make sense of but seem to follow a trend. There are 4 sets of chrono data found in this thread: http://www.airsoftcanada.com/showthread.php?t=51752 on pages 1 (middle), 3 and two on 5 compliments of Stalker and m102404 all using .2/.25/.25/.3 Bastards. I calculated all the energies from each individual fps reading, took averages of those energy values in for each weight (in each of the 4 sets of data) then calculated the percentage increase/decrease in energy (compared to .2 as a standard). Here's what it looks like:

Page...... 0.25....... 0.28....... 0.30
1........... 5.910%... -1.752%... 5.266%
3........... 3.388%... -2.792%... 2.433%
5.1........ 9.008%... 2.629%.... 8.815%
5.2........ 2.448%... -8.259%... 1.421%

Avg:...... 5.189%... -2.543%... 4.484%

Note for m102404's results I ignored the outliers (used the 10 middle values).

The trend is for .25's and .30's to actually increase in enegy and for .28's to actually decrease for some reason.

[m102404]

Thanks for the number crunching. I would have switched the chrono to Joules readings and recorded those values as well...but it would have taken forever and I don't recall if there is a 0.28g setting on the chrony.

NOTE: I initially had some very odd FPS readings from my single bag of 0.28's. It may have been a bad bag...not sure. I didn't have any others to test with. Also...I think that I used Madbull IPSC precision 0.20g bbs where as Stalker may have used 0.20g BBbastards.

Math is confusing...all I know for sure is that heavier bbs cut through leaves better and are felt more by the people being hit at extended ranges...LOL!

[Mitchell12]

I just remember the momentum formula from physics and know that P remains the same.

P=MV

P=momentum (oomph)
M=Mass in kg
V=velocity in m/s

I know it's not really useful but It's just how I think of it all.