I'm not a well-versed expert on military weapons or sound reduction equipment but I think Surefire; www.surefire.com
markets cans or AR units that can safely fire all types of 5.56x45mm(5.56NATO) rifle ammunition.
If your LE agency or PD uses sub-sonic 5.56mm loads that might work better.
I'd add that some cans are "self-cleaning" but with the salt water/marine/humid conditions may increase or speed up wear.
A good coating/treatment of Black-T or Green-T, NIC/Cerakote, NP3+, or Bearcoat may help protect the patrol rifle/long-gun.
www.RobarGuns.com www.Black-T.com www.Bearcoat.com