I have an early Manton hammer rifle with original chambering 470NE, 500 grain bullet etc. I have tried a both slow and fast powders (H4831, IMR4064, H4350) with the 500gr Woodleigh and the gun shoots wide about 5" at 75yds with all of them, wider with the fast powders in fact (although this may be because I was a bit more conservative with the faster stuff) even at loads close to maximum. Can anyone suggest a load that closely duplicates the first Kynoch loading? Does primer choice make any difference? I have used CCI250 for all the testing so far.