custom gun build help

[vinny1892]

hello;
ok well first off im building a 4 bore. Ive already built a few cases out of copper tubing with a brass plug to accommodate a 209 primer,plugs are silver soldered in. the id of the cases are 1.030.(its close to a 4 bore anyway). Now for a barrel I was thinking about a 1.027 dia tube of correct thickness. I already have a gun barrel maker lined up as well.The groove to groove dia would be 1.030. Is .003 depth for the rifling deep enough? I haven't decided on a weight for length of a bullet yet if that has anything to do with the depth. hope you can help thanks.
:veryconfu

[W.R.Buchanan]

No it is not deep enough. For a bore of 1" about .008-.012 deep on a side would be far more appropriate.

Typically rifling on a .30 cal. gun is between .004 and .005 deep on a side. The larger you go the rifling still has to be @ the same "Percentage" depth as it is on a .30 cal. or the bullets will have so much mass that the shallow rifling won't have enough bite to prevent stripping.

Many Large Bore Guns like you are talking about building had Paradox bores which consisted of a smooth bore with the last 2-3" rifled. The British had all this stuff figured out over 100 years ago.

Chrome-Moly tubing is probably available in 1.030 ID with a variety of wall thicknesses. .125 wall should be plenty. If you can't find that size you will have to have 1" ID tubing reamed and honed to size.

Did you get a job at Jurassic Park?

Randy

[vinny1892]

No it is not deep enough. For a bore of 1" about .008-.012 deep on a side would be far more appropriate.

Typically rifling on a .30 cal. gun is between .004 and .005 deep on a side. The larger you go the rifling still has to be @ the same "Percentage" depth as it is on a .30 cal. or the bullets will have so much mass that the shallow rifling won't have enough bite to prevent stripping.

Many Large Bore Guns like you are talking about building had Paradox bores which consisted of a smooth bore with the last 2-3" rifled. The British had all this stuff figured out over 100 years ago.

Chrome-Moly tubing is probably available in 1.030 ID with a variety of wall thicknesses. .125 wall should be plenty. If you can't find that size you will have to have 1" ID tubing reamed and honed to size.

Did you get a job at Jurassic Park?

Randy ill consider doing that with this barrel it will be easier to rifle 2 to 3 inches vs 26 or so. And ill look into that tubing u mentioned. Thanks

[blikseme300]

hello;
ok well first off im building a 4 bore. Ive already built a few cases out of copper tubing with a brass plug to accommodate a 209 primer,plugs are silver soldered in. the id of the cases are 1.030.(its close to a 4 bore anyway). Now for a barrel I was thinking about a 1.027 dia tube of correct thickness. I already have a gun barrel maker lined up as well.The groove to groove dia would be 1.030. Is .003 depth for the rifling deep enough? I haven't decided on a weight for length of a bullet yet if that has anything to do with the depth. hope you can help thanks.
:veryconfu

I watched a series of videos on the making of a double rifle in 2 bore. This smith has also done 4 bore rifles. He may be able to help you. Videos here: https://www.youtube.com/user/cstolzer338