it takes more than expensive parts to get your bolt action to run well (unless you're lucky). In my experience, people have pretty weird expectations of their guns compared to what they will tolerate when using them. For instance, you'll see people horribly dissatisfied with the range they get from a stock gun, do some expensive upgrades and then be completely content running their aeg without tuning their hop, just 412fps rainbow catapult. That said, there's also a lot of amateur upgrades. Using incompatible parts, installing things backwards, damaging hop rubbers, dangly bouncin around barrels, egg bb's, magazines that move hop units around all over the place... list goes on.
I can tell you for sure though, if you run a properly upgraded boltie (or even a stock marui, you'd be surprised how many kills you could get in the same situation with lower fps) for long enough, you'll have an awareness of how to acquire targets quickly and peg them precisely at long range. That coupled with enough experience fooling people and using cover properly and you can use the extra range to take on teams of multiple guys head on.
In short, you need both a properly shooting gun and loads of experience that can be frustrating to acquire to start getting in the positive k/d's but that's the main draw of bolt actions for most people. It's all about the challenge and once you get good enough you'll not only hold your own but become a serious asset. Last game I had the drop on 6 guys, took them all out before they could spot me in the open with 6 quick shots. Could I have taken them out with an AEG? Yep. Did I get a bigger battleboner doing it this way? Fuckin a right I did.