How do you regulate such a barrel?

As for the engraving? Really quite awful. Matches the whole appearance of the rifle, squat and dumpy looking.

Look at the "cheeky" cape buffalo!

The elephants are all on the "bottom of the page" like a immature five year olds drawing.

The leopards? Thankfully the lion and rhinos are too small ... really so much more could be said about the engraving ...
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The concussion the recoil would give one, is the best thing about this rifle ....