I think the mess comes from the misconception that sniper rifles are a particular exclusive subset of rifles. Historically, sniper's rifles were generally accurate hunting rifles which exceeded the consistency of general army issue firearms. In an early era when the first very accurate rifles were fired alongside smoothbore muskets the distinction was clear because general issue firearms were cheap to make in large quantity. Later on, rifles were more widely issued which featured certain tradeoffs in their design which facilitated manufacturing but sometimes at the cost of optimal accuracy so those particularly interested in accuracy brought out militarized hunting rifles.
You can snipe with pretty much anything if you clean it up and you have the skills. Take Mr. Hathcock for example. In Vietnam, he would sometimes shoot a cleaned up tripodded M2 because the tripod provided a very stable platform to huck huge BMG50 rounds over very long range accurately and BMG50 has excellent ballistics at long range. Does that make the M2 a sniper rifle?
I suggest that the term "sniper rifle" should not be used in airsoft where our ballistics are so crummy. Fieldcraft and ability to read the immediate conditions for a shot make a sniper, especially in our game, more than the rifle which might be specifically a bolt action rifle. I would say that if you took a really well tuned BA airsoft rifle and hand it to a goofball, the rifle loses it's status as a sniper rifle because of the inadequacies of it's bearer.
With RS things are a fair bit different. I got to shoot a Barret MRAD once which had been dialed in by none other than Chris Barret who was my spotter. Following his spotting instructions the rifle landed hits on a 1' steel plate at 1000yd on 2 out of 3 of my very inexperienced shots. That gun was an awesome BA sniper rifle because the spotter and rifle made the shot despite my inadequacies.
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