Questionable Gear

I have previously only bought/used pharm grade gear, I currently cant use my pharm because it is being investigated so I have to find a different source for a while. This brings me to my question, I have another source but the gear is being given out in large 10ml syringes. Apparently its from Thailand, I know people who use it and they have not had any issues but is there anything I should be worried about? Also would it be unwise to use the same barrel and just change the heads on the syringe?

Just keep the big syringe sterile and backload normal pins before injecting, then dispose.