I have a .416 Rigby Ruger M-77, early manufacture. I want to have it rebored to either .450 Rigby or Dakota. The question I have is, can it just be rechambered after rebore or do I have to have the barrel turned back? In other words, is there any diffrence in the .416 Rigby case and the .450 Rigby case other than the bullet diameter? Hope I mad my self clear and someone out there can help me.
thanks

The shoulder of the .450 Rigby is in the same place as the .416 Rigby based on the cases I have. I assume your trying to save the nice Ruger barrel and quarter rib. I believe I've heard that there is a potential problem in that the depth of one of the screw holes in later version Ruger barrels precludes reboring ,but I'm not certain as to whether this will apply to .458 caliber. I'm told the early Ruger .416 Rigby's don't have this problem and are much sought after for these type conversions.Call Cliff Labounty as he knows more about reboring than anyone and can tell you if it can or can't be done on your Ruger. In theory a rebore to .450 Rigby should onlt require a new neck/throat/leade on a .416 to .450 rebore.This could be easily done with a separate reamer that onlt cuts these surfaces and would not touch the shoulder.Thus, you could keep the original threads and barrel setback or re-timing may not be necessary if the reboring/rerifling can be done without damaging the rest of the chamber.
My guess is that will be very tricky to do. Again Cliff Labounty is the guy to call. Let us know what he says. I've thought about just such a project before and deceided that I didn't want to wait for Cliff ( he's backed up about 1 year now).-Rob

I understand that Dan Peterson also does reboring/rerifling with much shorter turnaround times - www.cutrifle.com

RGB, I think the problem you describe is only when re-boreing a No1, where the screw holes, and stud holes, for mounting the quarter rib are too deep. The M77 quarter rib is intragal with the barrel, no screws. There are no screw holes in the 77 416 Rigby barrel. ......NO?

MacD37,
I do believe you are right. Ruger did have a penchant for drilling those Ruger No.1 barrels too deep, in mounting the non-integral quarter ribs. I have also seen an old Ruger 44 RM carbine, Deer Stalker, that had its scope base holes (located on the barrel) drilled to within a "hair" of the chamber internal surface, by the factory. Hopefully they are getting smarter about this with the current guns.