It just works. Paste into the ini, edit if you like

[Lil' Slugger (Ultimate).esp]
;I chose arbitrary numbers based on original vanilla overhaul
10A2 = 7.89			;Ammo12GaSlugMagnum
10A3 = 7.12			;Ammo20GaSlugMagnum
10A7 = 1.42			;Ammo20GaBeanBag
10B2 = 1.25			;Ammo9mmFMJ
10B3 = 1.43			;Ammo5mmFMJ
10B4 = 1.69			;Ammo556mmFMJ
10B5 = 1.65			;Ammo10mmFMJ
10B6 = 4.12			;Ammo127mmFMJ
10B7 = 0.5			;Ammo22LRFMJ
139A = 1.66			;Ammo10mmJSP
139B = 4.26			;Ammo127mmJSP
139E = 4.32			;Ammo127mmHL
139F = 1.68			;Ammo10mmHL
13A0 = 0.69			;Ammo22LRJSP
13A1 = 0.65			;Ammo22LRHL
13A2 = 3.65			;Ammo44magnumJSP
13A3 = 3.55			;Ammo44magnumHL
13A4 = 3.83			;Ammo308JSP
13A5 = 3.33			;Ammo308HL
13A6 = 2.23			;Ammo357MagnumJSP
13A7 = 2.33			;Ammo357MagnumJFP
13A8 = 2.11			;Ammo357MagnumHL
1979 = 28.33			;Ammo12GaSlugEXP
197A = 29.33			;Ammo20GaSlugEXP
1F35 = 3.99			;Ammo44magnumJFP
1F36 = 4.02			;Ammo44magnumJFPHL
2ABD = 4.95			;Ammo20GaDragonsBreath
2DA1 = 0			;AmmoElectronChargePackHybrid
2DA2 = 0			;AmmoMicroFusionCellHybrid
2DA3 = 0			;AmmoSmallEnergyCellHybrid
2DA4 = 0			;AmmoSmallEnergyCellStun
2DA5 = 0			;AmmoMicroFusionCellStun
2DA6 = 0			;AmmoElectronChargePackStun
2DA7 = 0			;AmmoFlamerFuelPure
2DA9 = 0			;AmmoFlamerFuelNapalm
2DB1 = 0			;AmmoFlamerFuelPhosphorous
3EE5 = 2.22			;AAANVDLC02Ammo45AutoHL
3EE6 = 2.43			;AAANVDLC02Ammo45AutoJFPHL
3EE7 = 2.32			;AAANVDLC02Ammo45AutoJSP
3EEA = 6.66			;Ammo4570410
3EEB = 5.88			;Ammo4105Ball
3EEC = 2.00			;AAANVDLC02Ammo45AutoJFP
47C9 = 43.33			;Ammo556EXP
47CA = 1.63			;Ammo556INC
47F7 = 2.11			;Ammo45JunkRounds
47F9 = 1.52			;Ammo5mmMatch
4801 = 28.33			;Ammo308EXP
4802 = 31.22			;Ammo127mmEXP
4803 = 3.98			;Ammo20GaFlechette