this is more of a problem on the 527 and ive modified every on ive ever owned my self (covered in previous posts), it should not be a problem on your 550 unless your new scope has a very large mag ring indeed or mounted very far forward. i am not sure if a 44 obj will mount with the low rings, but i have mounted 50 s on med rings and the bolt functioned ok. on the rimfires the bolt handle can be a tad short, but unlike the 527 s ive never had one fail to clear the mag ring- some of the bolt handles (ball) are hollow and some solid both can be modified to take after market handles, the solid one ground down and then threaded to accept the new knob, similar to the rem 700 mod.