Hopefully, both you and Stan will forgive my moving your question to the WareWolf forum - I have been unable to post @ BrC for over a month now . . and there appears to be no remedy to that! ;)
>30BR/30 cal. Vertical Wind Effects
>Dropping a point out the bottom at 200 yards this weekend crystallized an impression I have had since I began to campaign a 30BR in Score shooting this season. I have come to believe that the 30BR, as I am shooting it, is more sensitive to vertical wind dispersion than a 6PPC. I don't think I can say I think there is a significant difference in horizontal deflection, but I have learned that I had better figure out what wind conditions were causing the up & down effects early in a match, or else I would be in trouble. Note that I am not talking about a random inherent precision issue, but repeatable, cause-and-effect vertical wind deflection.<
>My questions are: 1) Have other 30BR/30 cal. shooters noticed this relative difference in the amount of wind induced vertical movement? & 2) Is there a technical (BC related?) reason for this? (Randy?) If you are an experienced 6PPC AND 30BR shooter, I am interested in your perceptions. BTW, My 30BR loads are using Randy's excellent 112 gr. BIB's at about 3030fps in a 17T barrel, and my reference 6PPC loads are 66 gr. Euber's w/ 29.2 gr. N133 (fairly fast) in a 14T barrel. <
This is interesting, in that it runs counter to the math - in theory, the 1:17" twist/thirty caliber bullet combination should exhibit less vertical relative to wind drift. However, as we discussed at Mainville, the model is not exactly perfect. Joe Enterkin was experiencing a similar problem, which seemed to "go away" when he began shooting the H-4198(extreme) at about 34.5 grains (Joe uses the 118 Gr. bullets); this suggestets a tuning issue.
Another very good and experienced BR shooter, Dave Blazzard, of Utah, experienced the same thing - he reported that, via his .30BR - a 1:17" Lilja- he got MORE vertical, but less HORIZONTAL dirft associated with condition changes than expected . . .
It will be interesting to see what others have experienced via the 1:17 and 1:18" twist barrels; I certainly have not experienced anything like this via my 18" twist HBR and Vt class rigs.
Good shootin'! R.G.
