I took my scope to a gun shop and it was trial and error to find the right size. The gun shop owner was knowledgable, but what was suppose to fit didn't so we had to just keep trying different ones until we found the right fit.
Let me start off by saying I am not a farmer.
I am a deer hunter and I do own a tractor and have all of the equipment - but that does not make you a farmer any more than standing in the garage makes you a car - well, you get the picture!
Having said that - and with most of my ineptitude fairly well hidden - I do think that buckwheat is one of the most under rated cover crops out there.
I say cover crop because I see mixed results as it relates to the deer eating the plants.