Hi Bonanza !

I have just been working up some loads for my T Bland 577BPE 2 3/4 ,hammered underlever as well !
steel barrels ,28in long , I was using AR 2208 (Varget) with Dacron filler , 650Gr Woodleigh BP Slugs & Jamieson cases ,shooting at 50yds , 80Grs shot 4.5in high & 5in apart ,left barrel 1461fps Right @ 1413fps - 85Grs 2.5 high , 4in apart left 1553fps Right 1498fps - 90Grs 3in apart 1.5 high
Left 1755fps Right 1685fps - thats only 1.5 from the centre of my target bull , recoil getting stiff , 95grs is next and should be centred , my left barrel looks like new & right barrel is near prefect too , maybe left barrel is tighter hence higher velocity ?

Hope this can be of some help ?