Having some trouble finding load data for the 350 Rigby rimless. Anyone here load for this round? Thanks, Joe.

Hang in there,; one of these guys used to, was it Phurley or ScotinPA, or someone.
They'll come along shortly.

Joe,

I am about to begin load development for a 350 Rigby Magnum. The 350 Rigby Magnum Bertram brass is very similar in capacity to the 358 Norma Mag. Obviously the Norma is loaded to higher pressure levels, but I intend to use Norma Mag data as a starting point. Since the original 350 Rigby Mag factory load was a 225 grain bullet at 2625 fps I will start with a load for the 358 Norma that produces slightly less velocity with this weight bullet and work up from there. With powders appropriate for the 358 Norma this will allow for a good starting point without being higher in pressure than original Rigby ammo (assuming that I keep my loads at or below the original velocity level).

Keep in mind that you need to slug the bore first, as some of the original Rigbys had a .356 groove diameter. If this is the case you may need to adjust your loads downward slightly to stay within factory pressure levels (17.5 tpsi) with .358 diameter bullets. I would also be cautious about using monolithics in .356 barrels, but I do not know how much effect this might have on pressure or barrel wear.

I will be glad to share my results when I have time to do some load development if you would like, and would like to hear how you are doing as well. I would love to hear about, and see, a photo of your rifle .

Good shooting,
Jim

Thanks Jim. My rifle is an original Rigby Mauser built in 1921 and has been swaged to .358" Lucked out and bought the last of Huntington's Bertram brass @ 10$/box of 20! Dave at the very helpful Sierra tech center did some research for me and found a reference from Donaldson's which gave the following data. Case trim to length of 2.74" LOA of 3.57" 59 gr. IMR4320 duplicated factory MV of 2600 fps using a 225 gr. bullet.
I plan to start at 62gr. 4350 using 225 gr. NP's. Will let you know how it works out. Joe.

I think Paul H (moderator of Medium Bores and the Alaska Forum) has a 350 Rigby has worked a few loads for his. You might post this on one of the forums he moderates.