I have a 1:9 twist Shilen 6.5 Grendel that has proven accurate for me but I havent shot very many 129 grain bullets. I think Bill A. mentioned the longer barrels did well with 1:9 twist. The 1:9 twist was the traditional twist for the 264 Winchester Magnum and I believe the 6.5x55 Swedish Mauser plus MannlicherSchoenauer 6.5×54mm used 1:9 twist. The 6.5x54 M/S used some pretty long bullets. If I had the option of buying my Shilen with 1:8 twist in 2012 I wouldve bought it instead of the 1:9. Back then you were lucky to find any 6.5 Grendel barrels in stock. There are way more options today.
I bought one of the Group Buy 12 inch barrels with the fast 1:7.5 twist just because I was curious how it would compare to my PSA 1:8 twist barrel. Be sure to let us know how your AA 1:9 twist barrel shoots.
I bought one of the Group Buy 12 inch barrels with the fast 1:7.5 twist just because I was curious how it would compare to my PSA 1:8 twist barrel. Be sure to let us know how your AA 1:9 twist barrel shoots.