Well my brother picked up a Ruger M77 tang safety in .458 Win Mag the other day so yesterday we topped it with a new 2.5-8 Leupold in standard Ruger rings. I threw together some loads using 67 grains of IMR-4895 and 500 grain Hornady bullets, CCI mag primers and new unfired WW brass. Also loaded up a few more on up to 71.5 grains of IMR-4895 and same components.
The rifle was easy to sight in with no quirks and started shooting well in short order 1" high at 100 yards. Only trouble is the floor plate kept popping open so we'll have to work on that to fix it.
Fun to shoot but we both ended up getting a bit of bruising, we just didn't know when to stop.
Dug some of the 500 grain Hornadys out of the sand and they are impressive in the way they hold together.
My brother may use this rifle on his upcoming Utah Bison hunt just for the heck of it.
Gotta love the big guns!

Good stuff!

Be mindful that a 500gr. bullet might punch through on some shot presentations, endangering any animals standing behind the one your brother is trying to kill.

quote:

Only trouble is the floor plate kept popping open so we'll have to work on that to fix it.

Could your trigger fingers have been tapping the floorplate release under recoil?

George

quote:
Only trouble is the floor plate kept popping open so we'll have to work on that to fix it.
Could your trigger fingers have been tapping the floorplate release under recoil?

George I'm pretty sure we weren't getting any bump to spring it open, neither of us felt that tap. I think the edge of the keeper is worn a bit, we thought about trying to pin it somehow but didn't have any concrete ideas right off. Nice gun though and fun to shoot. Both of us have .375's but there was something more to the .458!
Thanks for the advice on the penetration of the 500 grain bullets! However both my brother and I are level headed shooters and have tons of big game experience, not prone to "herd shooting!" But thanks for the advice anyways.
I should have chronied the load we shot but I didn't bring it along.

I have a tang safety .458 that the floorplate pops open on. I took it to a smith and he "readjusted the floorplate". It seems to hold for now but I don't have much faith. I read an article written for Rifle magazine by Ganyana (An AR member) and he said that glass bedding helps w/ this problem. I will probably have this done but have been busy. I have also heard of people just pinning the floorplate shut. I was just going to have that done as I empty through the barrel LOL. But the smith talked me out of it. Good Luck!!!!!!!!

Perhaps the something is flexing under recoil.

George

This is the same thing my Ruger does, I would like to how you are going to fix yours? Other than the floor plate not staying lock I really like my rifle. Thanks John

That 45-degree angle Ruger front action screw might contribute to a little sliding play in the location of the floorplate,
Get it and the trigger guard locked in place by glass bedding, in proper, fixed position.
That will take out potential laxity due to the two-piece bottom metal.
Also make sure someone did not switch out the original steel bottom metal (standard on the .458WinMag M77) for the aluminum stuff.

Then consider possibly a stronger spring on the inside-the-bow floorplate release button.

Recoil makes the button tend to go forward due to inertia.

Last resort is a machine screw through the floorplate. You'll be sorry if you do that ... but it will never pop open again unless you unscrew that screw.

And what about a piece of duct tape to hold the floorplate shut? Makes a good place to carry strips of vinyl electrician's tape for the muzzle too.

RIP, thank you very much! John

Congratulation , Another 458 Fan ......................... The 77 MK II doesn,t pop open and it is aluminum .. At least they were until the Hawheye ...........

Yep, my RSM 458 Lott bested its floorplate "keeper" and I applied the field repair of duct tape to "secure" the mag floorplate unitl I can get it fixed properly!

John