Dave W
Aluminum
- Joined
- Jan 10, 2007
- Location
- central Arkansas
Bolt action rifles normally use raceways, large grooves in the sides where the projecting bolt locking lugs ride when the bolt is opened. The original designers and manufacturers used large dedicated machinery and long broaches to cut the raceways. It was cheap and fast for production work.
Cutting the raceways without big specialized equipment is awkward. Some people have modified commercial broaches to make the basic cuts, then used files to round the sides as needed. Others have used EDM. A few have used shapers.
A while ago I had another idea. (probably thousands of others have had the same idea...) You have a hole through a tube, and you want to put grooves in the sides of it.
Gee, where have we seen that before...?
I was sketching away when I'd realized I had just reinvented hook rifling.
Form the radiis of the outside of the raceway onto a piece of lathe bit, use a wedge and screw to adjust it, and take .001 or whatever cut would work per pass.
My air-over-hydraulic press doesn't have quite enough stroke, but I realized it should be practical to cut by hand, like the slotter attachments available for some older manual lathes. Bore and hone the ID of the receiver for a close fit for the broach bar, use a couple of links to keep the operating lever from putting a side load on the broach, and go to town. A .200" raceway in .001" cuts would be 200 strokes, times two for both sides, which sounds excessive... but loading a box of 50 cartridges takes 400 strokes on my O press, and I'll load a lot more than that at a single sitting.
"I love it when a plan comes together."
Cutting the raceways without big specialized equipment is awkward. Some people have modified commercial broaches to make the basic cuts, then used files to round the sides as needed. Others have used EDM. A few have used shapers.
A while ago I had another idea. (probably thousands of others have had the same idea...) You have a hole through a tube, and you want to put grooves in the sides of it.
Gee, where have we seen that before...?
I was sketching away when I'd realized I had just reinvented hook rifling.
Form the radiis of the outside of the raceway onto a piece of lathe bit, use a wedge and screw to adjust it, and take .001 or whatever cut would work per pass.
My air-over-hydraulic press doesn't have quite enough stroke, but I realized it should be practical to cut by hand, like the slotter attachments available for some older manual lathes. Bore and hone the ID of the receiver for a close fit for the broach bar, use a couple of links to keep the operating lever from putting a side load on the broach, and go to town. A .200" raceway in .001" cuts would be 200 strokes, times two for both sides, which sounds excessive... but loading a box of 50 cartridges takes 400 strokes on my O press, and I'll load a lot more than that at a single sitting.
"I love it when a plan comes together."