Hand drill is perfectly fine, and I've stated this before - you're not drilling a new hole, that has to be perfect. You have a guide for your new hole, right there - it's the original hole. It's hard to fuk that up, no offense intended. You're just making a smaller hole, well, larger. The template is already there. Stick a 1/4" (0..250") diameter wooden dowel down the barrel, to prevent you from pushing too hard and hitting the other side of the barrel. Which leads me to something else that I've recommended before...
Use SLOW drill speed with a variable speed drill, and LIGHT pressure on the drill - and just let the drill bit eat. Let it do it's job. You won't hit the other side, when you "break through" if you're using light pressure, and slow speed on the bit.
I drilled up one of these things (a 6.5 Creedmoor barrel) out in the desert a couple months ago, and got the gun running. Right then. At night, with a headlamp and a work light around. Dude's gun wasn't running, we looked at it, someone had a drill, someone looked up drill bit sizes on their phone - and I said "THAT is the bit we need!" Everyone was all nervous, and I said "Give me the drill and the bit, and stand back - I don't know how big this thing is gonna get!"
Two minutes, DONE. Gas block back in place, and he's shooting, and it works now.
This isn't Rocket Science, and you don't need alot of fancy protective parts to do this. You're just up-sizing a hole that's already there.