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Author Topic: 8mm BB FPS rules  (Read 3590 times)

Offline gixser13

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« Reply #15 on: April 04, 2005, 07:03:40 PM »
Quote from: "USMC-Greg"
Quote from: "andyhinds"
Quote from: "PissAunt"
yeah the marushin carbine is a single shot only, but i still dont know how to calculate the fps, is there a formula to use??

Don't calculate the FPS, crono it.

While it's not an official chrono that we will use at a game, you can get a good idea of your gun's velocity by shooting a coke can at point blank. I'm not sure if this table will work for 8mm bbs, but here it is. From redwolf's site:

-ONE SIDE (BB remains in can after penetrating one side) 290 to 310 fps
-BOTH SIDES (BB makes it straight through and exits on the other side) 350 to 370fps
-BOTTOM (CENTRAL) 430 to 450fps
-BOTTOM (EDGE) 450 to 470fps
-TOP (EDGE) 480 to 510fps
-TOP (CENTRAL) 520 to 540fps



I shoot  throught the top,straight through the bottom of the can how much is that?

 :twisted:
« Last Edit: December 31, 1969, 05:00:00 PM by gixser13 »
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Offline busta_cap

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« Reply #16 on: April 04, 2005, 08:44:11 PM »
Quote from: "gixser13"
Quote from: "USMC-Greg"
Quote from: "andyhinds"
Quote from: "PissAunt"
yeah the marushin carbine is a single shot only, but i still dont know how to calculate the fps, is there a formula to use??

Don't calculate the FPS, crono it.

While it's not an official chrono that we will use at a game, you can get a good idea of your gun's velocity by shooting a coke can at point blank. I'm not sure if this table will work for 8mm bbs, but here it is. From redwolf's site:

-ONE SIDE (BB remains in can after penetrating one side) 290 to 310 fps
-BOTH SIDES (BB makes it straight through and exits on the other side) 350 to 370fps
-BOTTOM (CENTRAL) 430 to 450fps
-BOTTOM (EDGE) 450 to 470fps
-TOP (EDGE) 480 to 510fps
-TOP (CENTRAL) 520 to 540fps


I shoot  throught the top,straight through the bottom of the can how much is that?

 :twisted:
Alot....Of pain? :shock:
« Last Edit: December 31, 1969, 05:00:00 PM by busta_cap »
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Offline woody

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« Reply #17 on: April 04, 2005, 09:21:59 PM »
Quote from: "azsarge"
Quote from: "PissAunt"
yeah the marushin carbine is a single shot only, but i still dont know how to calculate the fps, is there a formula to use??

Well, consider it as a ratio.  Use your algebra.

400 fps for .20g

___ fps for .XXg

Do the math.  Replace the XX with whatever weight you will be using, and cross multiply.

Probably getting ahead of most of the crowd here, Christian
« Last Edit: December 31, 1969, 05:00:00 PM by woody »
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Offline PissAunt

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« Reply #18 on: April 04, 2005, 10:57:28 PM »
that doesnt work cuz you come out with like 680 fps
« Last Edit: December 31, 1969, 05:00:00 PM by PissAunt »
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Offline Cochise

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« Reply #19 on: April 05, 2005, 08:01:32 AM »
What are you using to get 680?
« Last Edit: December 31, 1969, 05:00:00 PM by Cochise »
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Offline PissAunt

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« Reply #20 on: April 05, 2005, 02:10:34 PM »
.34x400 is 136 then divide by .20 and you get 680 with the cross multiply formula
« Last Edit: December 31, 1969, 05:00:00 PM by PissAunt »
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Offline heroicfighter199

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« Reply #21 on: April 06, 2005, 10:09:30 AM »
No, no, no! You gotta shoot someone then divide how loud he screams by the distance from the muzzle! :twisted:
NOTICE: My DORK friend posted this he got onto my account
« Last Edit: May 01, 2005, 07:22:15 PM by heroicfighter199 »
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Offline IcePlatinumSky

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« Reply #22 on: April 06, 2005, 10:24:54 AM »
Quote from: "heroicfighter199"
No, no, no! You gotta shoot someone then divide how loud he screams by the distance from the muzzle! :twisted:


Yep and then you have to Determine if that was an ARGGGGGHHHH or a WAAAARGGGGGHHHHHH!!!!! There is about 75fps of difference between the two. :lol:
« Last Edit: December 31, 1969, 05:00:00 PM by IcePlatinumSky »
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Offline Harley

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« Reply #23 on: April 13, 2005, 07:47:51 AM »
Quote from: "Cochise"
For things such as this, someone may want to invest in getting a chronograph that measures Joules.  I'm not sure if there is a projectile-weight setting on these, but that would simplify things a lot.


Well there's always the tried and true "Cimmarians" FPS converter.

http://www.cimmerians.com/FPS_Converter ... 0converter

Looks 383fps for .34 BB's is what you'll end up with using 2.32 joules.  This figure is based on a sniper gun using .20 BB's at 500fps.  Reverse calculations using 2.32 joules with a .34 BB gives you 383fps.
« Last Edit: December 31, 1969, 05:00:00 PM by Harley »
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Offline R10tGuNN3r

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« Reply #24 on: April 13, 2005, 01:25:56 PM »
Quote from: "IcePlatinumSky"
Quote from: "heroicfighter199"
No, no, no! You gotta shoot someone then divide how loud he screams by the distance from the muzzle! :twisted:

Yep and then you have to Determine if that was an ARGGGGGHHHH or a WAAAARGGGGGHHHHHH!!!!! There is about 75fps of difference between the two. :lol:


not to mention how fast they double over... but thats only for guns over 300fps...

on a more serious note...
would it be acceptable to upgrade an m4 to around 500 fps and only opperate it in semi auto mode? as long as its more than 50'

also... with the same m4 upgraded to 500 fps... would a bb break of some sort...(i've seen them out.. the correct terminology is slipping my mind) that could slow the bb down enough enable it for full auto feild play be acceptable?
« Last Edit: December 31, 1969, 05:00:00 PM by R10tGuNN3r »
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Offline Firehead

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« Reply #25 on: April 13, 2005, 01:51:04 PM »
Quote from: "R10tGuNN3r"
Quote from: "IcePlatinumSky"
Quote from: "heroicfighter199"
No, no, no! You gotta shoot someone then divide how loud he screams by the distance from the muzzle! :twisted:

Yep and then you have to Determine if that was an ARGGGGGHHHH or a WAAAARGGGGGHHHHHH!!!!! There is about 75fps of difference between the two. :lol:

not to mention how fast they double over... but thats only for guns over 300fps...

on a more serious note...
would it be acceptable to upgrade an m4 to around 500 fps and only opperate it in semi auto mode? as long as its more than 50'

also... with the same m4 upgraded to 500 fps... would a bb break of some sort...(i've seen them out.. the correct terminology is slipping my mind) that could slow the bb down enough enable it for full auto feild play be acceptable?


If the gun is modified to fire permenantly on semi(so the selector switch can't be set to full auto) then you can have it at 500 FPS, and you can't kill anyone under 50 feet. And I dont think many people would appreciate it if you aren't an actual sniper. (at least i think thats how it goes)

Fullauto with anything more than 400 FPS is not acceptable.
« Last Edit: December 31, 1969, 05:00:00 PM by Firehead »
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Offline Harley

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« Reply #26 on: April 13, 2005, 03:51:30 PM »
Quote from: "R10tGuNN3r"

also... with the same m4 upgraded to 500 fps... would a bb break of some sort...(i've seen them out.. the correct terminology is slipping my mind) that could slow the bb down enough enable it for full auto feild play be acceptable?


You're referring to a velocity reducer and no it won't slow down a 500fps bb to 400fps.  Maybe 20 or 30fps at the most and your accuracy will deminish as well.
« Last Edit: December 31, 1969, 05:00:00 PM by Harley »
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Offline PissAunt

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« Reply #27 on: April 13, 2005, 04:40:28 PM »
actually thats not true at all. i have first hand experience with the velocity reducers and they work amazingly well. i brought a full auto g36 from 430 fps to 300fps.
« Last Edit: December 31, 1969, 05:00:00 PM by PissAunt »
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Offline Raith

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« Reply #28 on: April 13, 2005, 04:56:24 PM »
Quote from: "Harley"
Quote from: "R10tGuNN3r"

also... with the same m4 upgraded to 500 fps... would a bb break of some sort...(i've seen them out.. the correct terminology is slipping my mind) that could slow the bb down enough enable it for full auto feild play be acceptable?

You're referring to a velocity reducer and no it won't slow down a 500fps bb to 400fps.  Maybe 20 or 30fps at the most and your accuracy will deminish as well.


The red insert for the velocity reducer takes my M4 from 400 FPS down to around 345 FPS with no noticable drop in accuracy.  The red insert is the 2nd weakest of the 4, so I'd assume that 100 FPS drops are possible with the stronger reducer inserts.
« Last Edit: December 31, 1969, 05:00:00 PM by Raith »
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Offline Harley

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« Reply #29 on: April 13, 2005, 06:44:06 PM »
Thanks for the correction guys, I've never delt with one myself and was just going by what I've heard.

Still, what he was suggesting won't work, since you need to permantly modify your M4 to shoot semi only to qualify for the 500fps sniper limit.
« Last Edit: December 31, 1969, 05:00:00 PM by Harley »
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