Rampage stacks which means you can run more damage together and you can get it to continue every time you get a kill and reload speed does not dictate it's effectiveness
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I prefer kill clip. Get 1 kill then I have about 3 seconds to move around before reloading to proc kill clip. Plus without a reload perk I can extend the time before engaging another person. The amount of distance you can cover in that timeframe is rather hefty.