Nikon calibrated this scope using a 55gr polymer tip round with a muzzle velocity of approx. 3240fps .... From what I could find they used a 20" barrel for these calibration purposes.

My question is, since my sport 2 has a 16" barrel, how much difference am I looking at? I know Nikon has the spot on ballistics calculator however I do not have access to a chrono , so I guess pretty much I'm looking for a hand out in the knowledge department lol .... Hornady rates their Varmint Express 55gr V-Max round at 3240fps (which is the exact round and load that Nikon calibrated the P223 for) however that is when being fired through a 24" barrel.

So now I have a scope calibrated with 20" barrel a round rated for a 24" barrel and I am trying to put it all together with a 16" barrel ..... needless to say I am no advanced mathematician and not a ballistics expert so I would really appreciate if someone was able to shine some light or point me in the right direction lol

Actually hard to say for certain without a chrono. However, a little searching and I found this.

Factory chrono data

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Peace was my Profession

I chrono'd LC 12 XM193 at 3020FPS out of a 16" barrel S&W, FWIW.

Looks to be in line with the link Westie1 posted.

Actually firing at targets is the only way to tell where you will hit even when you know the numbers.

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Hue 68 noli me tangere

Ballpark about 150fps loss of velocity 20in barrel to 16in.
3240fps Blue vs 3090fps green