All those thousands of posts by people advocating airguns or .22 rifles for a starting shoulder arm? Yes, listen to them. Starting with a Mosin-Nagant M38 will have you flinching with a Diana Model 25 (a delightfully machined chunk of Germanic blued steel that tosses 8.7 grain .177 'diabolo' wadcutter pellets at a leisurely 430 fps with boring accuracy from a 12-groove rifled break barrel).
And I'm not sure whether chunking away with said pelletchucker will cement said flinch or gradually heal it. Bollocks.
(Incidentally, if you shoot steel-cased surplus 7.62x54r, save the cases - they make neato-keen reactive targets. Hat tip to Xavier for the inspiration.)