The staking tool & the staples I have came are exactly like the ones TOW sell & they go in straight.
M O S T important you figure the thickness of the metal there & also figure in the rifling groove depth as well. Use a Drill Stop on the bit or a stop on a drill press.
Many many many guys have drilled right into the barrel.........
not good.....
I prefer to use a carbide milling bit when I do one so it has a flat tip rather than a angled tip.
Keith Lisle