I bought this gun and wish I hadn't. After getting it out of the box and airing it up I had to fix the airline running into the regulator, as it leaked like a sieve. I unscrewed it, put teflon tape on it and put it back together, thankfully it worked. The marker works well when it works but there are quite a few quirks. Screws in the grip can jam the trigger if they are tightened too much. I also had a problem where when I unscrewed the bolt to apply a coat of Sl33k, much to my dismay there was a small fitting in the gun where air enters the chamber that had cut grooves into the bolt sleeve leaving metal filings and basically wrecking the bolt sleeve... another problem. I could send the gun back to SP but then I have to pay shipping To and From the factory just to get the gun into the shape that it should have been in when I originally purchased it.. hardly something that I should pay for. It also likes fresh batteries. Sometimes while you are playing and it seems like the gun is shooting intermittently or 'freezing' a fresh battery should get things rolling again! It's really a gun that you have to get to know.
I probably got a lemon but I have heard that others have had some problems with them as well. I have a friend with an SP1 as well and he's had 2/3 of the problems I've had too. I guess it's an ok gun for the price but it seems that there are bugs to work out. You really have to work on this gun quite a bit, more than any other I've had before.
I just got the sp-1 w/blackheart and after shooting mine and taking it apart I saw the same thing was happening to my bolt sleeve. I called smart parts up and got taken care of fast. The woman told me they would take care of it asap and that if i included my shipping receipt that they would reimburse me for paying shipping. Give it a try, im impressed already and I didnt even have it a whole day.