Hello, I am in the process of doing a Saiga x39 hand guard conversion. I ordered a gas tube, the guy said it was Rommy. I thought any gas tube would work. But if you see from the pics, the gas tube is about 0.25" too short. It is way loose, thinking there must be a difference in the tubes. Can someone tell me what to look for next time. Will a AK47 vs AK74 gas tube be the same, please school me, thanks.