Where to get bsa R10 mk2 tuned?

Is there anyone in the US i could send my r10 mk2 to get a tun? I've never worked on it or tried tearing it down and dont know much about tuning it. It's shooting 18gr jobs in the mid 700s I'm wanting a speed that will most benefit for long range accuracy. Most of my shots are 50yds too 100+yds. What's yalls suggestions. I still have the stock regulator. I haven't had time yet to get a full shot string to see if it's working properly yet but soon as I get the time I will.