If your friend isn't worried about a mil/moa setup, I highly recommend the Mueller Tac 2 scope.
For around 270 bucks your get really good glass with capped target style turrets.
For three hundred, when on sale, the weaver grand slam tactical can't be beat.
These are IF he is interested in tactical style scopes.
If he is not concerned about "tacti-cool" scopes, there are plenty of good hunting scopes to be had for 300 bucks.
There is no 300 dollar scope with a top end of 20X that he should even consider.
I have an old B&L elite 3000 4-12 scope with fingertip adjustable turrets (can't reset).
It has decent glass, not spectacular (I used to think it was really good till I got my IOR), but it has ALWAYS held zero and spent considerable time aboard my 7mm magnum. Bushnell sold the model for a few years as an elite 3200 model, but no longer catalog it.
They do, however, have this:
Bushnell 4.5-14x44 Legend Ultra HD Rifle Scope
Weaver has this:
Weaver 4-16x42 Buck Commander Rifle Scope
Leupold offers this, which is a dandy little scope:
Leupold 3-9x40 Mark AR MOD 1 Riflescope