Until I can get some pressure test data for for BLACK MZ I will be doing my testing with my re-lined Armi Sports 56-50 Spencer.So far I have used 35grs of Black MZ and tried 3 types of bullets all sized to .516 ,Rapine 350-.520,Rapine 375-520 and the NEI 395-523 with the NEI bullet giving the best accuracy,I have tried CCI br 2 LR primers,CCI LPP and CCI LPP with under primer wad with the CCI LPP giving the best results.I tried Lee Liquid Alox for lube but for some reason I was getting sticky extraction so I changed to my BP lube(bees wax and olive oil)this fixed the extraction problem.Tests were done of the bench at 50 meters ,5 shot groups,best group was all holes touching repeated 3 times to be sure ,this load was Starline 56-50 brass,CCI LPP 35grs BLACK MZ ,no over powder wad ,NEI 395-523 Bullet sized to .516 lubed with bees wax olive oil mix.I then tied it on the 200 meter 12 inch gong and after getting the sights set hit it 15 times in a row I gave others a go and all had no trouble hitting it,we fired 40 rounds without cleaning and the was no change in accuracy and barrel was cleaned up with just a couple of patches and a drop of Hopies 9 ,no leading.All thing taken into acount this seems to be a very good BP sub but I just can not get over the thought that I am cheating when useing it in BP compitition,this does not stop me useing it when hunting pigs