.458shooter - the 8x57 has a CIP max load for factory ammo at 57,000PSI. At that pressure, it will easily match the .30/06 for speed with the same bullet weight, depending on the powder used. That meanes it will do 2,450fps with 220gr., close to 2,800fps with 180's and 3,000fps with 150's - given the 'right' powder, just as the '06 will do those speeds with the 'rifle' powder.

The larger bore/groove diameter of the 8x57 over the .30/'06 increases the 8's expansion ratio. This makes up for the reduced case capacity of the 57mm case and allows the smaller case to match the ballistics of the larger .30/06 round. When re-chambered for the '06 case, the performance is thus enhanced to the tune of about 100fps over standard. That means it will quite handily make 3,100fps with 150gr., about 3,000fps with 165's. With X type bullets, that's a good load. If that's worth the change, go for it. Be aware you will need to neck turn or inside ream to get rid of the donut that forms inside the case neck (neck/shoulder junction) when necking up '06 brass. It can be a pain in the butt.