I think you would need a 26" barrel to get close to those speeds. This from Hodgon's site.

180 GR. NOS E-TIP Hodgdon H4350 .308" 3.340" 62.1 2730 52,300 PSI 66.8 2916 62,600 PSI
180 GR. SPR MT-SP Hodgdon H4350 .308" 3.285" 63.0 2787 46,400 CUP 67.0 2918 53,100 CUP



Good Shooting!