CZ550 MAGNUM, 458WM Situation

[Riflecrank]

This has been much like watching a train wreck …..
Aside from that, I am intrigued as to what is going on with this rifle
Gumpy

My guess is that there is nothing going on,
nothing that is not a standard, SAAMI/CIP-chambered, .458 WIN MAG CZ 550 Magnum.

Lies go around the world three times before the truth gets its pants on.
That may explain Ridge Runner's confusion.

 

[Riflecrank]

 

[Riflecrank]

 

[Riflecrank]

BTW, "Throat Jump" above was what I was calling it before I started calling it "Slug Jump."

 

[Riflecrank]

Above are feed dummies reperesenting the actual handloading results in one specific rifle.
Note that these feed very well in a CZ 550 Magnum rifle.
They are a better fit for that +3.8 mag box length than the shorter SAAMI .458 Lott factory loads of generally about 3.585" COL.

 

[Riflecrank]

If you are stuck with a SAAMI .458 Lott rifle, you can fix it with a throat from the overall longer cutting reamer of the SAAMI .458 WIN MAG.
Get a reamer with noncutting belt or just be very careful with the standard SAAMI .458 WIN MAG.
Then you too can have a .458 Lott+, a .458 Lott Like Jack Built.
Feel safe in firing top .458 WIN MAGA loads in your new rifle.
Don't do it in a SAAMI .458 Lott.
Remember Art Alphin and moonshine in Kentucky, where the SAAMI .458 Lott was finalized.