reduced loads for a 416 Rigby

[onehousecat]

Due to advanced age and a very serious car accident last December, I need to find some reduced load data for my 416 Rigby. I have access to 350 and 400 grain cast gc boolits. The most appropiate powders available to me are Unique, 2400, IMR 4198, and 4759. If a load requires the use of a dacron filler, please mention it with the load. I’m a long time pistol cartridge reloader, but my rifle reloading was limited to semiauto cartridges. In the last few years, I became infatuated with Ruger #1s. The 416 loads will be shot from a Ruger #1. Any help will be appreciated.

[Bigslug]

For my CZ 550, I ended up doing a progressive load work-DOWN (the only rifle for which I've done this) from listed 350 grain bullet data for Accurate 5744 until I got to the middle 1800 fps range, but I wouldn't call that a light load - it just doesn't detach your retinas anymore. It'll be a couple days before I can get you the exact charge, but can throw it up if you'd like.

[15meter]

This:

https://castboolits.gunloads.com/showthread.php?92124-416-Rigby

[elk hunter]

Years ago I looked at a #1 in 416 in a shop in Idaho. The shop owner told me he had sold the rifle several times and each time the buyer would bring it back and trade for something a little less vigorous. I've not shot a #1 in 416 but did try one in 458 Lott. The owner of the Lott was surprised when I asked if I could shoot it a second time. My Rigby is one I put together on a P-14 Enfield action. With cast I've had decent results with 40 grains of 5744 with a 400 grain round nose and 45 grains of H-4198 with the 400 RN and a 350 grain flat point. Both bullets are plain base and were cast with air cooled wheel weight metal. I plan on trying the same loads with both bullets cast from linotype.

[TurnipEaterDown]

4th Edition Lyman Cast bullet Handbook has just such loads for 416 Rigby, w/ a 350gr RCBS GC. SR4759, 5744, and W748 showing lowest starting velocities (1700-ish). They also show loads of 3031, 4064 & 4895 that Might be able to be reduced a little.
A friend has a 416 Rigby that we had loaded w/ compressed 8700, and got 22-2300 ish fps, so, uncompressed might do what you want too.
I wouldn't leave too much airspace in that, but when I went looking for reduced cast loads in my 416 Taylor w/ the 350 RCBS I did get 8700 running at 1800 fps w/ 20 SD for 32 shots and Very round primers (almost no flattened annulus). Didn't shoot too bad for offhand practice. Switched to other powder later, but it worked OK.