M416 Trailer By Ossum Fixes

Just a few fixes I have made for the trailer by Ossum. First is the axle. Had issues slicing with S3D.

Also re configured the front spring mount to use just the 3mm hole for the screws as there is no shackle in the front.

Updated the front mount with the proper size 3mm hole for the hardware and also moved the hole down a little to allow more material around the top.

Redid the axle and leaf springs. Had to flip the nut inserts to the other side witch meant moving the holes over to cl