12 Guage Rifled Throats

[missionary5155]

Greetings and a Blessed Veterans Day
I have decided to purchase a real 12 Bore Boolit as will be produced by "338RUM" down in Group Buys. Seems like a good place to start moving up from .685 RB in smoothbore barrels.
I am wondering about 12 guage rifled barrels. Do they generally have a conventional "throat area" in front of the chamber similar to a cartrige rifle throat or is it more of an abrupt "cone" as found in most smoothbore "shotgun" barrels ?
Mike in Peru

[hubel458]

Most Rifled shotgun barrels have the same 9 degree forcing cone
as the smoothbores. I built the first 12ga FH with rifle type
throat with a lathe, and later ones with regular cone.
Couldn't se any difference. The length of wad column and/or
sabots is long enough that with the cone they seal ok and
column gets into rifling straight before it is out of case.. Ed

[missionary5155]

Good morning
Thank you Hubel458. Have not shot any "boolits" in a 12 bore rifled barrel yet being content with RB over the years. Going to be another of those good adventures we get to enjoy in the pursuit of accuracy.
Mike in Peru

[OnHoPr]

IMO I am not sure about the actual chambering and forcing cone or lead, but I do believe that there are individualities in each particular gun. Though I do believe there is a difference in the smoother lead and the ringed lead when it comes to wad slugs and possible full bore slugs. The heavier sabot seems to be less effected with the ringed type lead because it has thicker material.

[jmort]

This shows Winchester "Back-Bored" and typical chambers

87349

[OnHoPr]

I am not sure if my 835 slugster rifled barrel is back or over bored. I don't think the rifled 835 is over bored though. But if you look at the lead or forcing cone of many barrels there will be a smoother looking taper, a more adrupt taper, and a taper that looks ringed or threaded like the choke threading at the muzzle. I believe this last type of lead can cause havoc with wad slugs. I haven't tried a full bore through it, but might assume that it would shave lead before actually entering the rifling.