Originally Posted by
Harter66
What I said was that the slower twists out ran the faster twist and that it is the same and same margin whether cast or jacketed.
I think the questions could be answered with a 1-10 and 1-16 bbl chambered in 300 RUM were used with reduced case capacities to 308,x57 ,06' 300WM and the RUM on 1 rifle . Then use 1 powder retumbo or 1000 or W857 . Cut both chambers on the same day with the same tool and take extreme steps to ensure that only the twist is different between the 2 bbl. This will remove case shape ,throat, leade , land groove ,length ,weight ,taper, stock ,shooter fit ,trigger, hammer fall, sights/optics, bedding, heat distribution, lot variations and more variables. It leaves only 5 lots of 20 well matched brass and particulars of 300 weigh lotted bullets . Of course there could be atmospheric as well . With so many more variables removed it should be possible to prove that twist does or does not make any difference and that cast can or can not be pushed to jacketed speeds. Since speed is the quest I futher suggest that no more than a 165 gr maximum loaded weight bullet be used . I should think that loads should be fired in the 1-16 bbl 1st then the same loads in the chamber matched 100 new brass be fired in the 1-10 twist bbl .
As a last confirmation use loads that work in the 1-10 twist in the 1-16 .
The down side of this is of course having a spare magnum action and bench rest stock along with a couple of grand to drop on bbls and fitting just laying around .