Sizer for 0.730” boolits needed

[ohnomrbillk]

I’m working on a 12 bore project. Mould is coming from accurate. My barrel has a 0.729” groove diameter. I plan on trying a 0.730” sized book it.

My Lyman 450 doesn’t appear to be up to the task at hand.

Any recommendations on where I can source a sizer this big?

Thanks in advance.

[country gent]

Even a push threw sizing die like a lee is going to need a bigger die hole than the 7/8 14. 1 1/4 12 would do. Heres what your looking at for this, 7/8 14 threaded shank is actually around .812 at base of threads - .730 = .082 / 2= .041 wall thickness at base of threads even figuring the full 7/8 dia it is .072 wall thickness. I dont think theres enough there to hold up with out going to the 1 1/4 thread dia.

On the h&g sizing dies I think the od is close to the dia of the hole itself

One of the presses with the bushing removed will give the larger dia thread required for this. Or a push threw could be made for a arbor press with a ring sizer to set on the bolster plate.

[megasupermagnum]

Accurate molds can hold tolerances plenty tight for shotgun purposes. Since throat fit doesn't matter (shotguns do not have throats), and you can fit a grossly oversized bullet and still have it chamber, the diameter is not super important. Anything .729" all the way to .735" is perfectly fine for your gun. I've shot bullets as big is .737" in a .731" groove rifled barrel, and even shot a .743" round ball through the same .731" groove rifled slug gun. If you order that slug from Accurate as a .729" +.002" tolerance, there is a very good chance they will drop from the mold dead on at .730". He is incredibly good at making molds.

If you still want to go for a sizer, my recommendation is to make a die set to be used in something like an arbor press. I would ask Lathesmith on this forum about this. You would essentially be looking for a giant version of his Star sizing dies.

[ohnomrbillk]

...hold tolerances plenty tight for shotgun purposes.

Not a shotgun. True 12 bore. Similar to 729 Jongman.

I’ll ask Lathesmith.

I have 1.25” x 12 tpi and also 1.5” x 12 tpi presses available.