@G.Patton I find it interesting that you are reacting ammonium chloride with sulfuric acid to make your HCL gas in this write up. I've never before heard of using that method but it is viable. Is there a reason that is preffered over the more common mixtures?
The tartaric acid method works by selectively crystallizing d-methamphetamine as the l-tartrate salt. Control pH carefully during freebase conversion and HCl gas saturation. Hot filtration and recrystallization in ethanol boost purity but reduce yield (~30% loss normal). Always verify purity with Simon’s test. Exact tartaric acid ratios and repeat crystallizations improve results.