So I'm snooping around the LGS a week or so ago and I find a Knight LK93 inline with a scope that looks unfired for $150 and took it home. Yes I now know I paid too much for it. Anyway i found a friend that gave me an old breech plug wrench. Not the correct slot tip wrench, but a 7/16 hex that I groung on the bench grinder to make a slot tip and removed the #11 breech plug and installed a 209 full plastic jacket kit. I got some .50/.452 sabots and some .50/400 sabots and a bunch of FPJ primer inserts as well. Got a can of 777, wavered between the 2f and 3f and decided on the 3f due to the short 22" barrel and hoping I can get the lighter .40 cal bullets to shoot well. I looked up the owners manual online and found that Knight rates the LK93 for up to 150 grains of BP or equivalent and they say usually 90 to 120 grains is optimal (250 to 300 grain 45 cal bullets in a sabot). I cleaned any oils out of the bore and installed the new breech plug (with grease) per the instructions and finally got to the range today. I figured I would start with the .50/40 sabots and some of 180gr .40's I cast for my .38-40 (RCBS CB mould). Since I am starting with a lighter bullet I should go with a higher starting load I will try 120 grains by volume in the black powder measure. Right? When I load for cartridges, lighter bullets with the same powder (almost) always start higher and max higher. First shot recoiled like a hot 30-06. The guy on the bench next to me (shooting an M44 Mosin) says "****...that's loud". First shot...15" left at 50 yds. spun the adjustment 3/4 turn right and dropped another 120gr in the barrel and seated another 180 .40 sabot. Cocked the bolt to remove the spent primer and reprime and found the FPJ with the primer had been blown off the nipple and was laying sideways between the nipple and the hammer/bolt/striker whatever you want to call it. Looking closer the primer itself is an 1/8th of an inch out of the jacket and the inner piece of the two piece 209 primer is .065" out of the outer piece. What to do?...Call me a dim bulb, but it didn't blow up on the first shot so I reprimed and dropped the hammer again. Impact is a foot to the left of the first shot (see my scope adjustment above). Okay maybe the scope turret is labeled backwards, spun it 1 1/2 turns right. Now, lets drop the charge to 90gr....Thats a 25% reduction to the starting recommended charge for a much heavier bullet. recoil is much more manageable and impact is about 2 1/2" left...now we are getting somewhere. next shot with 90 gr is 9" left and 15" low. 1 more shot without moving the scope adjustment and I could have done better with a load of 00Buck out of well...pretty much any old shotgun. Upon closer inspection even the 90 grain loads showed signs of waaaay high pressure to my eyes. I am thinking of backing off to 60 grains and trying again. I am thanking GOD i didn't start with the 310 grain cast .45's or the 300 grain .45 XTP's.
Does this whole BP/substitute thing work differently than smokeless in regards to bullet weight vs powder charge vs priming system? would the powder charges behaved differently if I had been using the #11 caps? does going to a 209 require a reduction in powder charges?
Two primers in front were with 120 grains of 777. 3 in the back are with 90 grains. 180gr .40 cal cast bullet naked and in a sabot.