Neither, I would do 300rum first...here is a pretty good read on the Jarret......Main reason, there is quality brass available for the Rum(including bartram), the rum has more power, is an inherently accurate round, is available in many different rifle configurations and is a long range killer....
300rum...Throws a 230 berger @3200 fps at 62*.........
Attached File
Distance to Chrono(FT): 15.00
Ballistic Coefficient: 0.717
Bullet Weight(gr): 230.00
Temp: N/A °F
BP: N/A inHg
Altitude: 0.00
#
FPS FT-LBS
PF
5 3218 5289.51 740.14
4 3221 5299.38 740.83
3 3214 5276.37 739.22
2 3208 5256.69 737.84
1 3214 5276.37 739.22
Average: 3215.0 FPS
SD: 4.9 FPS
Min: 3208 FPS
Max: 3221 FPS
Spread: 13 FPS
Shot/sec: 0.0
True MV: 3220 FPS
https://www.longrangehunting.com/threads/300-rum-or-300-jarrett.32848/