¼-20 Glass Filled Nylon Socket Head (Sold in Pairs)
Not all nylon bolts are the same. These are glass filled and machined threaded. If you look closely at most wing bolts they are molded out of nylon, and not machined. The difference is that the thread pitch varies and they can be difficult to torque due to their stretching and twisting. The ultra scary part is if you throw a set of calipers across them it will shock you how one varies to the next.
These have 40 times more pull strength and feel almost like a steel bolt when tightened. Machined to SAE tolerance, they are a cheap piece of insurance. Current data of most 80’s classic pattern planes shows more than 8G’s in many cases that is more than 80lbs of pull on the front bolt.