Advanced Rifling Tips - 1
On the next few pages you'll find a few tips to help prevent some perplexing problems and it's all stuff I use here at Toad Hall. It's all knowledge you might need to know one day. It is O.K. to copy any Advanced Rifling Tips pages and put them in your copy of A Wooden Iowa Rifling Bench. If you encounter any problems at home while rifling with my style of rifler, Stop what you're doing and don't ruin the barrel. If you can't figure it out, contact me and we'll see if we can get you back on track. Who knows, I may even put the solution in this department. Remember, while rifling always start slowly and easily so you can get the feel of how everything is working. A jammed cutter or a loose bit are situations that call for immediate rectification.
Situation: I have a barrel blank that has already been breeched and I don't want to cut riflings into the threads or cut the breech off, OR perhaps my barrel is shorter than the rifling worm and I don't wish to make an additional worm.
A picture is worth a thousand words, but here goes. Get thee a piece of round steel stock that is larger than the outside of your barrel. If you have a lathe, or know someone who can do this work for you, drill a hole in the center of the round stock that will be the same diameter as your bore. Then cut threads on it to match the threads in the breech. (It is O.K. if the threaded portion is a bit longer than the depth of the threaded breech.) Now cut the drilled portion of the round stock off and you will have something that is similar to this:
The large portion of the bushing can be almost any length, but the less you must rifle, the longer the cutter bit will last. If your rifling bench was made to accommodate a standard 42 inch barrel blank and say you have a blank that is only 40 inches long, make the overall length 2". That way you end up rifling a 42" barrel without further modifications.
Bevel both ends of the bushing. On the large end, the bevel is deep. This gives you some draft to prevent the cutter bit from jamming at the start of the stroke. A light bevel is taken on the threaded end to provide draft, just in case your bore and the hole in the bushing are not exactly matched.
Screw the bushing into the breech until it is finger tight. Then use pliers to tighten just a teensy bit more. All you wish to do is prevent the bushing from vibrating loose from the vibrations cause while rifling. IF you tighten it too much, Houston, we have a problem. The hole in the threaded portion will collapse and prevent the cutter head from passing through. If you did it anyway, remove the bushing and file or grind off the damaged section, screw it back in and easy does it this time. Here is what the bushing might look like when it's mounted in the barrel blank.
This bushing is not rocket science so your own common sense should tell you what dimensions your bushing needs to be for your particular issue.
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