That's okay! I bet, mechanical stuff is a nightmare. I've been teaching myself to draw real guns (given I live in the UK and it has a gun ban, Google UK must be having a field day with my reference searches, they probably think I'm starting a militia!) as I'd spent ages basically just drawing whatever came to my mind (it normally looked kind of like the old Namco G-Con lightgun lol) and I know what you mean. All the little parts and stuff.
I find pistols pretty straightforward (although I can now have a bizarre conversation about how a Glock is harder to draw than a Beretta lol) but rifles and the like elude me. They just always end up all over the shop lol. I normally just sketch loads of crappy pics til I start to get it to come together then I use the better pics to inform what I'm doing on pieces. I would say just go for it