I have only used 1 Weaver and 2 Warne/TC Maxima Bases on my 3 barrels. They all have that gap at the taper. Its doesn't look real nice, but it doesn't seem to cause any problems. The screw holes are far enough back on the flat part of the barrel to hold the base in place and the bases are pretty rigid.
I put the Weaver on my 209x50 barrel 5 years ago because that was all I could find locally. Although I never had any problems with it if I ever decide to upgrade the scope I would also upgrade the base to the Warne/T/C Maxima. Can't beat steel.