Best thing to get is a well built aeg that shoots just as far but is full auto and has no engagement distance.
Was looking at a dmr not long ago that someone had put lots of time and money into and had locked it to single fire.
It got about 5 metres more range than my gun and was no more accurate (I actually thought less accurate but didnt get chance for a proper test) and I only have a 247mm barrel length. I actually think the whole sniper rifle/dmr thing is a bit of a waste in airsoft.