The Columbia 300 Burst would be the closest thing to the Rival that is in the current line-up as far as specs goes on both bowling balls.  The Burst RG number is .03 lower than the Rival, so it will be a little earlier on the lane and the diff. are exactly the same.  The surface on both balls are at 4000, the only thing I don't know is if your ball came with polish or not because the burst does.  The burst is a medium oil bowling ball but the surface could be change to make it stronger. 

 

RG/Diff:           (15 lbs) Balls:

2.49/.040          Rival

2.46/.040          Burst

2010 is the first time joining a league since 1999. Over a 10 year lay off and I haven't lost much of my game.

HG-300 x 1, HS-780 (Nov. 2010)

In the Bag:

Columbia World Beater
Columbia Outburst
Columbia Ransom
Storm Invasion
Columbia Pure Swing
Columbia Burst
Storm Natural
Spare ball-T-Zone