I used a Brass Eagle Tiger Shark...I can't really compare the two, though.
CORE The Sharc with everything it came with, except the sight rail. 20 oz CO2 tank, 200 Viewloader Hopper, PMI gun oil, PMI Universal hopper elbow.
Nothing really. I've never even tried a different barrel.
Appears to get better with use, uses CO2 wisely, can turn velocity above legal limit.
Poor shipping and I received an incorrect manual in the mail.
The grips on it are a different shade from the green that I got, and they look dorky, but who really cares? The stock 12" barrel is awesome. The gun doesn't field strip really fast, but if you are like me, you'd rather it stayed together in the field while playing. A bolt needed tightened right above the expansion chamber when I got it. For the people that the expansion chamber leaked air, it probably wasn't the chamber, it could have been this bolt that you can find inside the area the expansion chamber screws into. With all the pain that this gun brought me at first, the way it works now makes up for it. I just needed to experiment with it, and find little things that make the gun work better, like a good cleaning every time you use it, something other than Brass Eagle paintballs, and PATIENCE. The gun hasn't given me a hassle since 3 months after I got it, which makes 9 months of fun after that. Delivering the upgrades with the gun is a good idea. (Drop forward, low pressure chamber, expansion chamber, etc), they just need to be put together more carefully by the manufacturers. I got a 2 year warranty with the gun for $30, so I can get a part replaced if it quits on me. The invisible bolt action is something I had never seen before until I got this gun. The bolt is a little hard to cock now, it must just need worked more often. If your cocking mechanism gets rusty like mine, you shouldn't need to cock the thing again unless you run out of CO2 or something else goes wrong. Just cock it before the game starts, no big deal. The sight rail that the gun came with was kinda dumb, I didn't like it, so I just took it off. Why do you need a sight rail for a paintball gun anyways? Just point and shoot, the balls will curve whichever way they feel like anyways. That's about as ridiculous as people with lazer sights for their markers. I just replaced a couple o rings on my bolt after a whole year's use. I'd recommend putting a little oil on your CO2 tank's threads before screwing it into the gun because it can be pretty hard to get out of the gun, wasting a lot of gas if you're struggling to get it unscrewed. I couldn't fit the next few sentences in the key strengths and key weaknesses: for the strengths, Care needs to be taken to get the gun to work better with use, the expansion chamber, drop forward and low pressure chamber all make the gun use CO2 wisely, and you can turn up the velocity above legal limit to bring some pain to opponents you don't really like. For the Weaknesses, I received a manual for the CORE Hammerhead, what the heck? It's a good thing I understood paintball guns good enough without a manual, but I'm thinking of the poor chap that this is his first paintball gun and he goes to look at the manual and he sees a CORE Hammerhead.
I recommend this gun if you have patience. You also need to take care of your gun and try to find the conditions that it prefers when you get it. Since most people don't have patience, you shouldn't waste your precious time with this gun, but this review was written for the other people. The score it got is the way it performs NOW, not when I first got it. If I had written a review 10 months ago I would have said something like, "The dang thing always has something new to go wrong" and given it a 3.