SCAR with a Silencer is beast, ACR takes too long to drop them with a Silencer, even with Stopping Power, and I like to use suppressed weapons as much as possible.
Recoil
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The ACR has ZERO recoil based on recoil charts.
The SCAR has a tiny bit of recoil that isn't noticeable at all with the iron sights. Damage
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The ACR is 30-20(M4A1, F2000 damage).
The SCAR is 40-30(FAMAS, M16, AK47,Tar21 damage).
Range
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The ACR has longer range than the SCAR.
The SCAR is stronger at farther ranges than the ACR.
Iron Sights
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The ACR has decent iron sights.
The SCAR has fantastic iron sights.
Mobility
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Same
Clip Size
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ACR 30
SCAR 20
Overall the SCAR seems like a much better gun. It basically comes down to what you prefer. Higher damages with a tiny bit of recoil or Low damages with zero recoil. The choice should be pretty easy if you ask me lol. The clip size only makes a difference of one kill and thats IF you don't miss which probably wouldn't happen.
SCAR 3-3-3-3-3-3-2 -Six people dead
ACR 4-4-4-4-4-4-4-2 -Seven people dead