Conversion of M70 Classic Safari Express 458WM to 458 Lott complete. Took it to the range today. Prior to conversion the gun was a tackdriver with WW factory 458WM 510 gr SPs, big ragged holes. These fired and cycled well after conversion but the groups opened up. Then shot old redbox Hornady 458 Lott and IT is now the tackdriver. 2 big ragged holes. All afore mentioned shooting done at 50 yds. The gun is 9.1 lbs unloaded. It kicked some.

Sweet! Did you happen to do a before and after chrony?

No. The Win factory stuff is 2050 or about. Hornady...?? I'm going to handload Lott cases to moderate velocity, that was my goal. To be able to shoot 458wm factory ammo, fine. To be able to shoot factory Lott loads, great. But the real deal for me is to make the 458wm what it should've been! I'm going to explore the 450 gr meplats too. I was convinced in the other WM/Lott threads that these bullets/loads are the ticket too. Same for 470NE. Was second guessing not having got a 500NE but if the Capeshok chronos OK then the 470 Trophy Bonded Sledgehammer will do anything a 500 will. These flatnose solids are awesome.

I'm thinking the same route to get 2150 with ease. May just do the magazine first and long load. I'm not going to buy or use a reemer myself and I'm a little chicken when it comes to going to the gunsmith. Who did the chamber if you don't mind me asking? Did you have the barrel stamped?

Showbart, I have been down this path in regard to your plan to improve your 458 velocities. I have a CZ 550 with a 21" barrel. 458 WM with Barnes 450 gr banded solids, seated on the 2nd groove from the front, 79gr H335 or AA2230 give about 2260 fps. The 500gr bullets, seated on the 3rd groove from the front and 76 gr AA2230 give about 2160 fps. I just tested some 450 gr Northfork cup points, long loaded with 79 gr AA2230 and got around 2250 fps. An important caveat is whether or not they will feed in your rifle. The 450's have a little less shoulder thump than the 500's and they both work very, very well on bufalo. Hope this helps.

Snowbart, I have the CZ 550 American Safari 458 Lott. I have put three bullets into 5/8" at 100 yds and three into 1/2" at 50 yds These bullets were going 2280 FPS for the 500gr and 2210 for the 550gr. The 500gr are Hornady the 550gr are
Woodleigh both soft point. The powder is IMR4320. My solids go 2320 FPS.

Excellent!

My shoulder's fine, the M70 bangs my cheek. I'll install recoil reducer and steel glass bed it to get the weight up. A PH would love it at 9.1 lbs tho.

I'm going to work with Lott cases and with bulkier powders.