The Bighorn is rated for up to 150 grains.

Ive heard of guys getting good axccuracy with 150 grains.But I only tried it a couple times and wasnt happy.I'm better off around 110 or 120 depending on bullet

The guys at Bobs in Longview told me the Knight pros said that 150 grain loads leave about 20% of the powder unburnt.So they recommended satying 120 or less.