I come up with two things:
1) I don’t think it’s about rivet strength, but rather the Top plate. The rivet hole is very close to two edges of the material, and cutting a chamfer means even less material to take the load.
2) As someone mentioned earlier, most rivets on earlier weapons have round heads. It was probably common practice to use round head rivets whenever possible; no need for cutting the countersink or grinding the head after peening. Cutting a chamfer in the inside of the Top plate will require a milling operation and a custom cutter. Is it really worth all that trouble when a pan head will work. The profit motive tends to eliminate unnecessary machining operations.
MSG
1) I don’t think it’s about rivet strength, but rather the Top plate. The rivet hole is very close to two edges of the material, and cutting a chamfer means even less material to take the load.
2) As someone mentioned earlier, most rivets on earlier weapons have round heads. It was probably common practice to use round head rivets whenever possible; no need for cutting the countersink or grinding the head after peening. Cutting a chamfer in the inside of the Top plate will require a milling operation and a custom cutter. Is it really worth all that trouble when a pan head will work. The profit motive tends to eliminate unnecessary machining operations.
MSG
