bb weights with WE G39C

[Carlito564]

Hello, if I were to use a .30g bb weight with the WE G39C would it change my FPS at all? Or would the higher bb weight just use more gas and keep my same FPS?

[spartan117]

Originally Posted by Carlito564

Hello, if I were to use a .30g bb weight with the WE G39C would it change my FPS at all? Or would the higher bb weight just use more gas and keep my same FPS?

... heavier bb's = lower FPS

[ShelledPants]

Originally Posted by spartan117

... heavier bb's = lower FPS

Only marginally so with gas guns.

For example:

AEG @ 400fps with .20g = 400fps
with .25g = 380fps
with .28 = 350fps
with .30 = 330fps
etc...



WE GAS RIFLE @ 400fps with .20g = 400fps
with .25g = 390fps
with .28g = 380fps
with .30g = 370fps

kinetic energy is HIGHER with WE GBBR's than AEG's with heavier weight bb's.

The above is not a scientific approach and is merely theory based on experience. If someone has a chrony and an AEG @ 400 w/ 2g and a WE @ 400 w/2g, you will see what I mean.

[Carlito564]

ok thanks, i was just getting mixed info about this and just wanted to clear it up

[Sha Do]

Just keep in mind that for crony purposes for field limits that you must use .20 weights. You can use what ever you like on the field, but you can not use a heavier weight to bring you down to field limit (i.e. you cannot use 30 weight to bring a 440 fps gun down to the field limit of 400 fps as your gun is still technically shooting 440 fps).

SHA DO

[Styrak]

Originally Posted by ShelledPants

Only marginally so with gas guns.

For example:

AEG @ 400fps with .20g = 400fps
with .25g = 380fps
with .28 = 350fps
with .30 = 330fps
etc...



WE GAS RIFLE @ 400fps with .20g = 400fps
with .25g = 390fps
with .28g = 380fps
with .30g = 370fps

kinetic energy is HIGHER with WE GBBR's than AEG's with heavier weight bb's.

The above is not a scientific approach and is merely theory based on experience. If someone has a chrony and an AEG @ 400 w/ 2g and a WE @ 400 w/2g, you will see what I mean.

Your numbers with AEG aren't that accurate. From my experience it's
400 fps wuth 0.20
360 fps with 0.25
330 fps with 0.28

BB Bastard calculator which is available at http://msed.bbbastard.com/index.php?...d=53&Itemid=57

Shows:
400 fps wuth 0.20
358 fps with 0.25
338 fps with 0.28

[Auto_Demon]

i have the we g39c with a barrel extension w/ silencer that basically makes it the same barrel length as the K. but i use .25g bbs and they work fine, my friend keeps telling me to upgrade to .30g but my guns already sighted in for .25. not sure what they chrono at but i know that with a .20 in my gun using propane it chronos at 450-520 fps

My friend has the g39e and he has the 500fps upgrade so with .20g hes shooting about 550-610 fps

[Brian McIlmoyle]

Originally Posted by Auto_Demon

propane it chronos at 450-520 fps

My friend has the g39e and he has the 500fps upgrade so with .20g hes shooting about 550-610 fps

Spicy!.. no strangers to pain

[ap27]

I thought I read somewhere that GBBRs show an increase in FPS with heavier weights, due to a larger/longer buildup of pressure/gas behind the BB.
Am I mistaken?

[Brian McIlmoyle]

Originally Posted by ap27

I thought I read somewhere that GBBRs show an increase in FPS with heavier weights, due to a larger/longer buildup of pressure/gas behind the BB.
Am I mistaken?

yes you are... they show an increase in muzzle energy , which is a measure of the kinetic energy of the projectile.

muzzle energy in AEGs is fixed by the volume of air in the cylinder. so it drops as the projectile mass increases..

The force that a bb hits with is pretty much fixed with a AEG regardless of the weight of the projectile.

Heavier projectille gives you more stable flight over a longer distance, and greater penetration through leaf cover.

With gas guns .. the volume of propellant is not fixed.. with a heavier projectile, the time that the gas valves remain open and delivering gas is stretched out as it takes longer to accelerate the bb out of the barrel with a heavier mass..

so the heavier the bb the more gas is delivered to propel it.. the more Muzzle energy it will have upon leaving the barrel.

[Grizzly0679]

is there any reason why a game would not let someone use a bb weight higher than .20 with an AEG?

I ask b/c for some reason I thought .20's were necessary for AEG's at most games that require 350fps or less, but if heavier bbs slow it down then that should fix my problem. (I'm firing a little above the 350 mark, though its a brand new rifle)

[Styrak]

Originally Posted by Grizzly0679

is there any reason why a game would not let someone use a bb weight higher than .20 with an AEG?

I ask b/c for some reason I thought .20's were necessary for AEG's at most games that require 350fps or less, but if heavier bbs slow it down then that should fix my problem. (I'm firing a little above the 350 mark, though its a brand new rifle)

If you're using an AEG it doesn't matter what weight you're using. Using 0.20's is just for chronying purposes.

[Grizzly0679]

Originally Posted by Styrak

If you're using an AEG it doesn't matter what weight you're using. Using 0.20's is just for chronying purposes.

Sounds made up. (my favorite line from the movie Signs).

Just kidding. But that's my issue. With .20 Im firing(chrono) at like 375. So what, slap in some .28's and Im good?

[Brian McIlmoyle]

Originally Posted by Grizzly0679

Sounds made up. (my favorite line from the movie Signs).

Just kidding. But that's my issue. With .20 Im firing(chrono) at like 375. So what, slap in some .28's and Im good?

no you are not good

your Muzzle energy is still the same with a .28

your gun is too hot to meet the FPS limit regardless of what bb you are firing

When we Chrony with .2 what is being measured is the Muzzle energy.. .2 at 350 is considered by most as the TOP END of the limit for close quarters shooting.

You need a downgrade to use that gun for close quarters

[Grizzly0679]

Ah, gotcha Brian. I did downgrade; got an m90 spring in my KWA M4A1. Hop up set at its max too. Rifle is a beast!