260rem,
I hunt some thick Sambar country with a 26" barrel on an 8mmRemMag and its no problem ... I'd be careful in assuming cutting from 24" to 20" will make the rifle "handier". In my opinion, handiness comes from perfect balance ... not overall length. I'd be tempted to cut it to 22" and try it before taking another 2" off. Each cut will cost $50. You get it wrong and you'll regret it, and start adding weight to finetune the balance again.
Handiest 375H&H I had wore a 22" barrel in a heavy Remington magnum contour ... the Remington sporter contour suited a 24" length. At least that's how it felt to me.
Cheers...
Con