Originally Posted by johnboy
I'm a long time reloader but have never necked down a case to make a wildcat cartridge.I've just ordered a new Bullberry Contender barrel in 6mm Bullberry Improved which is probably identical to 6mm/.30 .30 improved or a 6/30 Waters Improved.I've ordered the dies also but I dont have any experiance with necking down the .30.30 cartridge.Is there somewhere I can find step by step procedures to do a good job necking down and fireforming the cartridges..Any help would be appreciated...Thanks Johnboy
I think the recommendation to ask Bulberry is very good.
I have a .30 Gibbs and cases for it must be fireformed.This is based on a 30/06 case with a sharp shoulder moved forward and a short case neck.It increases case capacity about 12% over the '06. The Gibbs will hold about 4-5 more grains of 4350 than the Ackley Improved will.
In order to get a shoulder to hold the case against the bolt head while fireforming,some reloaders will expand the neck of a 30/06 and then partially neck it back to .30 caliber.
I do it different - I neck down new .35 Whelen cases to the point where the bolt will close with some resistance.Since this thickens the neck considerably,I use an outside neck-turner on a Forster case trimmer to reduce the neck thickness and uniform the necks.
For a fireforming load,I use reduced loads with any 30 caliber bullets that I no longer want.
Some people have reported using light loads of a fast-burning powder with a tuft of Kapok stuffed on top of the powder,but I haven't tried that.
Other people have recommended seating the bullet out far enough that it jams in the lands to support the case,but my experience is that the firing pin will drive the case forward and you end up with a "stretched" case.