There WILL be the teams like Hawk45 describes, but there will be some serious as well. There are plenty of gun enthusiasts who think anything the gov does is just hunky dory. In any event, asymmetric counters are called for, plus you will have to deal with the pissed off perimeter cops and sniper elements.

That's if they can envelop you. If you're mobile, a sniper would be harder pressed to set up, but if air assets are available, they will be employed and you will have to figure upon open hostilities that they will be armed w/at least a belt fed, and maybe later on mounted rocket pods and cannon.

Drones are quickly being introduced into the LE toolbox-the operator will be guarded so unless you have allies/cohorts near them you'll have to deal with it... for locals it will likely be an up engined and armed model derived from an upmarket RC but then again it may be a Predator at 10,000 feet. The number and battlefield saturation of these stand off weapons depends on production and aquisition, availability and of course when the open warfare actually starts.

Still, having a few allies trained in rifle tactics, even with Mosins firing between buildings a couple hundred yards off can throw off any OPFOR raid plan. Also, simply getting them into a foot chase when they're geared toward strength or simply bulk and bravado can open up possibilities so long as you don't run up against a gun enthusiast who chose to wear blue. Thems the breaks.