Do you have a SCAR 16S?
) The ACR's muzzle break has a much softer report to both the shooter and bystanders, the rifle stays on target and I am able to get "A" ring double and triple taps on a NRA tomb stone target at 25yards. The front heavy barrel of the ACR might help with this. If you had to have one which one would it be? I was so on the fence with this for a long time now because the prices have come down on both. The SCAR feels better in my hands and is lighter. The sights are excellent and I do like the cheek rest, seems to fit me better. I am able to mount the rifle much faster. I like the fact that you can change the grip on the scar too, the ACR grip is ok. The recip handle sucks and is positioned in a not so good location. The stock to me seems weaker then the ACR and overall I found the ACR built a little nicer. The concussion blast really sucks but that helps that barrel stay down with the FSC556, without it I believe it would be climbing a little. A Battlecomp should take care of that nicely both noise and concussion. I dont like that you cannot changes cals but that isnt a deal breaker for me. I have no idea how it is to clean but I know first hand the ACR is pretty easy! Let me know...I was always curious. I was also on the fence with an LWRC. Really like them quite a bit!I own both rifles, the SCAR has the factory muzzle break and the ACR is an enhanced with the AAC blackout attached.
IMHO, I feel that both rifles stay on target fairly well and have minimal muzzle rise. The SCAR's muzzle break does an excellent job keeping the muzzle down, how ever the thing is LOUD and you can feel the concussion. (I cleared out an indoor range when shooting it one day
My conclusion, I am seriously concidering replacing the SCAR's factory muzzle break with an AAC blackout or battlecomp. The PWS muzzle break is effective and does what it's designed to do, but it's just toooo LOUD.
of course YMMV
That is a hard question to answer, I like both rifles for what they are. At this moment, if the SHTF and I had to grab a rifle and run it would be the SCAR. (Ask again in 6 month, that might change
)With that said, this is at this moment, the money the gov't poored in to perfect / improve the SCAR system shows. However, the more I shoot the ACR, the more comfortable I feel with it. It's seeing more and more range time and I have never had any problems with reliability with it. 
