Thanks guys. I thought I might have had to pull the bullets and add more powder. I'm going to take them to the range today and try the gun out.

Well, congratulations, you are the first person that I know of who has personally experienced a secondary explosion!

I'd be quite reluctant to drop the charge of 4350 as low as the manuals recommend.

It IS a relatively slow-burning powder, after all, and there are better choices for the reduced-velocity role. If I was doing this for MY .416 Rigby, I'd use something more in the 4895/4064 burning-speed area.

Even though the manuals "allow" 4350 loads at the weights mentioned here, I have experienced one blow-up from SEE following a hangfire with H4831, and I intend to err on the side of caution whenever possible.

Actually, most of my reduced-load work with the Rigby uses cast bullets with great success, but that's another subject.

Regards from BruceB (aka Bren Mk1)

IMR-4350 From 73.5 grains to 101.0 grains
Federal 215 Primer

Hornady's Fith edition says the starting load for a 416 Rigby, 400 gr. RN using IMR 4350 is 73.5 Gr. max load is 88.5 Gr. Now if you mean H4350 the starting load is 63.9gr the masx load is 90.5gr. (The 416 weatherby magnum starting load for h 4350 is 89.6gr the max load is 103.5gr)

I recently purchased a 416 Rigby and also got a partial box of loaded rounds with it. The previous owner left a note in the box stating that they were loaded with Fed 215, 86gr IMR4350, and 400 gr Hornady RN. My Hodgdon manual has a starting load of 92 gr of IMR4350 for this bullet weight. Does anyone think this is too light of a load for this slow powder? I am concerned about detonation when using too light of a load of slow powder. Has anyone seen data with a lighter starting load for IMR4350 than is in my Hodgdon manual?

Thanks, Hart