With a $7 flashlight fiber optic adapter
NITE IZE Adapter, Fiber Optic, AA - Flashlight Accessories - 5XR78|FPO-07-AA20 - Grainger Industrial Supply
I don't think they make them any more, but a few are still in stock in a few places.
I can see the last 1" of the bore very well with a magnifier.
I grade barrels, and the A+ goes to those that are factory honed.
Last month a built three rifles with Shilen stainless barrels that were factory lapped.
I ran out of time and just had to buy what Brownells had in stock and could not wait 3 months for barrel man.
The "select match" barrel was A+ as expected, but the two "match" barrels were not.