I'd recommend the 30-30AI, I shoot the 125gr Sierra SPT at over 2800fps in my 22" Handi-rifle, I don't know if the Contender will handle that pressure, but it's factory available in 375Win which is what brass I use for my 30-30AI handloads.

Tim
Trajectory for Sierra Bullets .308 dia. 125 gr. SPT at 2800 Feet per Second At an Elevation Angle of: 0 degrees
Ballistic Coefficients of: 0.279 0.277 0.264 0.264 0.264
Velocity Boundaries (Feet per Second) of: 2800 2000 2000 2000
Wind Direction is: 0.0 o'clock and a Wind Velocity of: 0.0 Miles per hour
Wind Components are (Miles per Hour): DownRange: 0.0 Cross Range: 0.0 Vertical: 0.0
Altitude: 0 Feet Humidity: 70 Percent Pressure: 29.53 in/Hg
Temperature: 59 F
Data Printed in English Units
Range Velocity Energy Momentum Drop Bullet Path Wind Drift Time of Flight
(Yards) (Ft/Sec) (Ft/Lbs) (Lb-Sec) (inches) (inches) (inches) (Seconds)
0 2800.0 2175.7 1.55 -0.18 -0.11 23430.58 0.000000000
25 2716.9 2048.4 1.51 -0.14 -0.14 0.0 0.027192530
50 2635.4 1927.3 1.46 -0.58 0.93 0.0 0.055221561
75 2555.3 1812.0 1.42 -1.33 1.68 0.0 0.084123330
100 2476.6 1702.1 1.37 -2.41 2.1 0.0 0.113936634
125 2399.3 1597.5 1.33 -3.84 2.17 0.0 0.144704346
150 2323.3 1497.9 1.29 -5.65 1.86 0.0 0.176471044
175 2248.7 1403.3 1.25 -7.87 1.14 0.0 0.209283881
200 2175.4 1313.3 1.21 -10.52 0.0 0.0 0.243193756
225 2103.5 1227.9 1.17 -13.62 -1.6 0.0 0.278254863
250 2032.9 1146.9 1.13 -17.21 -3.7 0.0 0.314524125
275 1962.0 1068.3 1.09 -21.34 -6.31 0.0 0.352070051
300 1891.1 992.5 1.05 -26.02 -9.5 0.0 0.391006699