looks awesome man. The only thing i see is it's a small thing but on real bolts the end of the thread or end of the bolt is chamfered yours the thread just stops it would never work in the real world you could not get it started on the bolt hole. sorry man im kinda critical on that stuff i use them all the time to build bikes.
Yes, could have been fixed easily - I saw it too, but i got so busy with the textures, I forgot about it till after the render and I thought "fuck" - no one will even recognize it. But of course you did, thanks for the critique anyway!