My .69 has a 1-1/8" octagonal barrel, straight and 30" long. It handles up to over 200gr. of powder just fine, but shot best with 165gr.2F, GOEX BP. this gave me 1,550fps with it's 484gr. bullet. It has a GR barrel with a faster twist than I wanted but was all that was available in that calibre in 1986.