Anyway, these equations were written to answer a specific question:

"Right now I have x FPS and y ROF, what will my ROF be if I lower my FPS to z?"

NOTE: In order to use these equations you need 2 measurements about your gun: The current FPS and the current ROF, there are many ways to get these measurements but if you can spare the cash a Chronograph that also has a ROF mode will be the easiest and most accurate method.

NOTE 2: if you have a good understanding of algebra and percents, you can just skim this to see what my equations are, but I go into detail on how to use them to better accommodate those who don't grasp mathematics as well as I do.

NOTE 3: Everything in here assumes a chrono with a .2g bb both at the beginning and the end

My Theory:

Given no changes besides a weaker/stronger spring, my theory is that FPS and ROF are directly related as the determining factor in both categories becomes the same. Namely, how hard it is to pull the spring.

Therefore, when changing springs, shouldn't the percent increase or decrease in spring tension [FPS] reflect the percent increase or decrease in ease to pull [ROF]?

Given this as true, we can now use simple percent calculations to predict the ROF at any given FPS.

How to run the numbers:

**Step 1: percent change in FPS**

What we are doing here is calculating how much the FPS [spring tension] changed in terms of a percent.

In these problems, the initial FPS and the final FPS are known/predicted, and are expressed as if and FF respectively.

Percent change in FPS = if / FF * 100

percent change in FPS is equal to Initial FPS divided by Final FPS multiplied by 100

EXAMPLE PROBLEM:

percent change in fps =

400 if / 300 FF * 100 =

4/3 * 100 =

.75 * 100 =

75%

**Step 2: percent increase in ROF**

This part is much more simple, all we need to do is take the percent found in the first problem, subtract it from 100% and add 100% to that value to set up the right number for the next problem.

Here the only needed data is the percent increase in FPS, which we got with the last equation, and will be expressed as %IIF

percent increase in ROF = [100% - %IIF] + 100%

percent increase in ROF = [100% - percent increase in fps] + 100%

EXAMPLE PROBLEM:

percent increase in ROF =

[100% - 75%] + 100% =

125%

**Step 3: So what's my ROF CheeseWiz?**

Okay, in this step we finally get to figure out what your [theoretical] ROF will be with your new FPS

Here the only things you need to know are you percent increase in ROF [which we figured out in step 2] and your current ROF [which can be measured by some chronos or an audio recording software, but you can find out how to do that somewhere else on ASF]

theoretical ROF = percent increase in ROF * current ROF

Now, a quick tip, when multiplying, you have to multiply the percent increase as a PERCENT, not as a normal number. Most calculators have a button with the % symbol, just hit that and it will figure out the percent for you, otherwise, take the percent increase in ROF and divide by 100 [it should be around 1.xx], then use the answer to this problem in place of the percent increase in ROF as a normal number.

EXAMPLE PROBLEM MULTIPLYING AS A PERCENT:

in this problem we use the same answers from our equations before, and we'll say you were getting 20 rps at the original FPS

Theoretical ROF =

125% * 20rps =

25 RPS

EXAMPLE PROBLEM MULTIPLYING AS A NUMBER:

Theoretical ROF =

125% / 100 * 20 RPS =

1.25 * 20 RPS =

25 RPS

Okay, so, now we know that if you have 20 RPS at 400 FPS, by doing nothing other than putting in a 300 FPS spring you should theoretically have 25 RPS. Fun little equations huh?

If anyone has any questions regarding the use of these equations feel free to PM me.

**Edited by CheeseWiz, 23 July 2010 - 11:03 PM.**