I now have the book for my H&R Model 623 revolver -- all three pages! Which, sure enough, has useful information I didn't know, like you really want to have the hammer on the half-cock notch to insert or remove the cylinder, and that the little notch on the cylinder shield on the right side is just to see if it's loaded, and should not be used to load the gun.
This is thanks to Rediscovered Shooting Treasures, who sells plenty more: repro OEM manuals for a wide range of small arms, hang tags for classic rifles and boxes for the Colt ACE and 1903, plus Savage and Remington Model 51 autopistols. And, from the note with my H&R booklet, how's this for a promise: "If there is ANY problem with your order please contact me. I WILL do anything I can to make it right and I do offer a full refund for any reason."
3 months ago