This isn't so much a question about the virtues of one over the other but in loading the former vs the latter. In theory, assuming a strong modern action without something weird going on, one would think a Rigby's load data would be essentially interchangeable with the Weatherby. Indeed, I've heard it said more than a little Rigby brass used to be made by simply turning the belts off the Weatherby. Before there is any great cacophony of "What's wrong with the Rigby at it's "classic" velocities?" the answer is "nothing". However, if more velocity can be safely gained while keeping (or who knows, even improving) accuracy what's the downside? (assuming recoil doesn't become overly objectionable)

First the obvious caveat; one should work up to the max loads even by Rigby standards. The idea of working up beyond that is, at it should be, a given. My question is are there specific reasons to avoid loading a Rigby towards Weatherby velocities? Possible issues being:

Is Rigby brass not manufactured to handle Weatherby pressure?

Could the Weatherby "freebore" be a big factor?

Any input appreciated for this decidedly "loonie" question.

My guess is that if you use Weatherby data in a Rigby case and the rifle does not have the freebore a Weatherby does ,you will have pressure problems.The Rigby does just fine at Rigby velocities.They were meant to keep pressures low at higher than normal temperatures.Why mess with that???

This was Jack OConners conclusion on loading up the Rigby to near Weatherby velocities. Too much recoil. He was using Weatherby cases too. Not sure which book had his data might be the Rifle Book. Keep in mind he was using surplus H4831 with a questionably calibrated scale to boot.

guyandarifle,

The Rigby case actually doesn't have quite the capacity of the .416 Weatherby, despite the Rigby's lack of a belt, due to some other minor changes in shape.

I did an article a few years ago for HANDLOADER that partially involved loading the .416 Rigby to "modern" pressures, and after some calculating decided 50 fps less than .416 Wby. velocities should be doable, which amounted to 2650 with 400's. It worked fine in my rifle, a CZ 550 Magnum, and recoil really wasn't all that bad. But I've never hunted with the higher-velocity loads, and in fact when I went Tanzania a year or two later used the standard-velocity loads. They killed a Cape buffalo nicely, just like they've been doing for over century.

So it would appear that brass or freebore really aren't a big issue. (with 50fps-ish being the difference while still safe)

Appreciate the input. I'm not really trying to make a Rigby into a 'Bee but it's nice to think one should safely be able to explore up into that general area without profound concerns you're pushing the Rigby that hard, assuming usual precautions of course. (mine is also a CZ 550)

Wrong-O. Weatherby freebore is a BIG issue, particularly when shooting Weatherby/Norma ammo, and when exploring the upper reaches of velocity. Always has been, always will be. Maybe 50-ish FPS is a decent place to stop when working toward Weatherby velocities, but rifles without Weatherby-style freebore definitely cannot handle the same powder charges as Weatherby rifles. Case in point: When I fired Weatherby 30-378 ammo in my Sako M995TRG/S magnum rifle so chambered, bad things happened. To its credit the rifle stayed together, but just about every other pressure sign you can think of (and some you wouldn't) showed up. It pained me to disassemble those Weeatherby rounds so they could be loaded for the rifle, but that is exactly what I did. The maximum charges I came up with were a full ten grains below advertised maximum charges in reputable manuals for Weatherby rifles.

I probably worded that poorly without specific context. I have no desire to actually try to be going over 2800fps with 350's or 2700fps with 400's. Now THOSE loadings I would think that freebore (or more specifically the lack thereof in the Rigby) could very well become an issue. More likely than not actually. It does however sound as though from MD's work that practical loads can be developed that, while short of full-on Weatherby velocities, can safely dip into the lower ranges of the Weatherby's loadings. (at least on a rifle by rifle basis)

Actually to your point I've got a Lyman manual that for the Weatherby calibers specifically states that the listed loadings are ONLY for rifles with Weatherby's freebore chamber dimensions.

You got it right, guy. Hope I didn't sound like a dick. Wasn't tryin' to.

Oh no it's all good. In fact your experience is a good cautionary tale for others to bear in mind. I appreciate the input.

Hang on fellas, the Weatherby does not have feebore. The .416 and the .240 Weatherby are the only 2 cartridges in the line that do not have a longer throat as even today's Weatherby's do not have the publicized freebore that was promoted back when the Mark V's were made in Germany with a lot of 12" twists across the range.

John

Yep. In fact SAAMI specifications show the throat of the .416 Rigby is a little LONGER than the .416 Weatherby's.

Well there's a little revelation. And once home and digging up the aforementioned manual, sure enough, no admonishment about freebore mentioned for the 416 Weatherby as opposed to other Weatherby calibers.

Thanks guys.

I have played around with RL22 and 400's in the neighborhood of 2700 fps in the Rigby and there is a noticeable difference in recoil to say the least. I have kept it to about 2500 with 370 North Forks since then. I think they are 2530 fps with H4831

With 4350 I split the difference, instead of the 90 grains listed for the Rigby and the 110 for the Weatherby I load 100. It doesn't make my 416 as flat shooting as my 300, but it does make a difference.

However, if I ever go dangerous game hunting I will be happy with factory rounds.