Seismic bowling's next release is going to have some pretty strong core numbers in the 13# area.  Unfortunately I can't give them out just yet but should be able to release some info in near future

Also, look into Brunswick and DV8.  They try to keep the core integrity in their lighter balls.

+1. My son throws 13 lbs and the Ruckus he got recently really impresses.  Also look at motiv. They utilize same care in lighter balls.

IIRC Track also seems to keep some fidelity at 13 lbs.

Second the Motiv suggestion. In fact if theyncant produce a say, 12# ball utilizing the same core shape because of the size of the core itself, they don't make that weight. Example, the size of the core used in the cruel series doesn't allow them to make those in less than 14...so that's the lowest they make.

Good luck!

Also, look into Brunswick and DV8.  They try to keep the core integrity in their lighter balls.

Brunswick, DV8, and many other companies use a generic standard light bulb shape core in their lighter weight balls that are under 14# and down.

Motiv uses the the exact same size and shape core in their lighter weight balls that they use  in their heavier balls and are one of the 2-3 companies that do this. Lane 1 does this also. This gives the lighter weight balls a similar look as their heavier weight balls. What they do is make the core a bit less dense to take off the needed weight.

After having back surgery late last year and being forced to drop to 12# balls (Dr's orders), I did a lot of research on this core-lighter ball thing and chose Motiv because of them using the same size-shape core as mentioned above and am not sorry I chose Motiv as their balls have worked perfect for me.

Prior to my back surgery, I was in love with Brunswick and DV8, but after finding them using generic light bulb shape cores in all of their light weight balls and not the cores meant for each ball, I was forced to switch to Motiv in order to get the same shape ball going down the lane as their heavier balls.