Training with a rifle that has a recoil that hurts a bit after several rounds is a recipe for getting a flinch. You have to know when to stop or change the recoil pad etc! A flinch will cause you to miss the bullseye or miss the target altogether. I run into folks that show me bruises on the shoulder after shooting too many rounds or shooting a large rifle caliber with a big kick/recoil and no protective gear.
Often the shooter does not pull the rifle firmly into the shoulder too, thus the rifle builds momentum and whacks you. Not so much if you pull it firm toward you.
A flinch is an unconscious brain and body reaction to the anticipated shoulder pain just before the gun goes boom causing you to flinch. It is perhaps responsible for more misses than you can count. How to reduce or eliminate flinch is to be sure to use a shock absorbing recoil pad. Many recoil pads on the market reduce felt recoil by 50 to 60%. They are around 50 bucks and worth every penny.
Secondly, lets say you do have a flinch. Get a hunting friend to load a round in your rifle or maybe make it look like he/she is loading a round for you to shoot down range. So you pick up the rifle, aim and squeeze the trigger, but just as you squeeze and the rifle goes click your body rears back in anticipation. Yep, sure enough you’ve got a flinch. Now a good practice is to shoot a similar rifle in a lighter caliber where there is almost no recoil. Shoot it for a short time and check for flinch, Your unconscious brain knows that you won’t get hurt so for a short time the flinch disappears. On a different day shoot and dry fire your rifle a dozen or more times each day for a week. Then shoot your rifle with a recoil tamer shoulder pad. Not much recoil your unconscious brain discovers. Do that again on a different day. You are retraining your unconscious brain to trust you. Now wear the heavy shoulder recoil tamer and pad and have your friend load the rifle that gave you a flinch and shoot it standing with a live round. Not at a bench rest. You may flinch a bit but your brain says, “Hey that didn’t hurt a bit with the extra pads”! So do that again with your friend with a live round. Your brain again says hey that didn’t hurt but flinched less. Remember to hold the rifle butt firm to your shoulder. Don’t worry about hitting the target, that will come. So, now you understand that repeating a similar sequence can slowly allow your unconscious brain to trust you again. Give it a try, it works!
Good Shooting!