Has anyone who has shot 62 grain bullets out of an NEF Single Shot Rifle with the 1 in 12 Twist gotten any appreciable accuracy? Thanks.......

Tac......

My 223 (not a Handi-Rifle) with 1:12 twist will shoot 60gr Sierra or Hornady's great. If your 62's are FMJ's, that is likely the biggest problem. FMJ's are notorious for inferior accuracy. No doubt somebody has them shoot okay, but odds are against it.
My best example was: some Federal American Eagle 62 fmj shot into a pattern, not a group, over 3". Pulled the bullets, substituted some 60 Sierras (no other change), and the load shot into 0.8"...convinced me!

Mine doesn't seem to care for anything over 55gr.

The slower the twist, the shorter the bullet that will stabilize. Round ball twist is 1 in 66". Try 40 to 55 grainers to see what they do in your barrel............Captain

How to tell the twist of a rifle.
Put a snug fitting patch on the jag and insert the rod in bore. Make a mark
@ 12 o’clock on the rod at the muzzle. Pull rod out slowly until the mark is
@ 12 o’clock and measure the distance
from the mark to the muzzle. The resulting measurement is the twist of your
rifling, ie.
1 turn in ____”.
There could be some slippage between
patch and rifling, but this is close enough for government work.