Letter "C" drill is listed as 0.2420" here on my handy dandy Drill, Tap Size Chart.Co7t said:In Silver Dollar's build tutorial, he used a letter C drill bit to gauge the space of the lower rails between the upper rail. Would anyone be able to give an approximate size of the bit for someone who doesn't have lettered drill bits?
You are correct sir! Letter C drill is only an "in the ball park" spacer. Your mileage may vary. There were some posts that indicated that 0.242" did not place the lower rail where it needed to be to let the bolt operate correctly.Toten Kopf said:A 'C' dril is .2420" but remember that the drill size given was for his build as a general dimension. You just need to make sure that the lower rails are parallel with the front trunion bolt slide tab and that will be 'your true' dimension. I'm sure that someone else here has a lot more experiance building than me but I do know that the lowwer rails are to support/guide the bolt into the front trunion. And on his build the 'C' drill was the correct size. Your's might be just a little different.
This is my understanding, if I'm wrong on this 'PLEASE' someone point it out to me so that I can correct myself.
That is an excellent point! I had not considered that! I will have to go home and check my Vulcan receiver to see how much space there is between the top rails and the lower rails and to make sure that the lower rails are 90 degrees to the receiver walls.7.62x39 said:Also, you want to make sure your upper rails are bent at 90 degrees to the side.
Any variation, more or less, will effect the lower rail height in relationship to the rest of the receiver.