I personally think the p90 would be the most ‘newb friendly’ but beyond that I can’t really say. I prefer the pump over any other gun and I’ve been playing cs/css for a long time. Simply put, I think its the ability the player has with the weapon that *edited*es someone off more than the player being new to the game and getting a few ‘spray kills’ in the process of learning 
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A skilled player with the cp90 would naturally be more effective with any weapon over a person who just started playing the game 
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Just my thoughts ^^