To be obnoxious.
"Any healthy, full grown shooter could handle a 375 w/o a brake."
Sorry to disagree with you. My friend Alex shoots more than I do. He owns a few 308s and some assault rifle toys. He cannot tolerate the recoil from my 375 H & H. He fired 300 grain factory rounds three times and pronounced, "I can't take this."
Maybe I am cut from the same wood as Alex. A wimp, you might say. I can only tolerate around 10 rounds from my 10 pound CZ 550. After that, I start to flinch. I am both healthy, full grown. I am fat as well.
To be more obnoxious . . .
Repeatedly firing a powerful rifle until you flinch makes no sense to me. You can build up tolerance to recoil, over a short period of time, you just need to have enough self discipline to be patient and the desire to prevail. Everyone has their limits and everyone's limits are different. But once a flinch is developed it can take a very long time to overcome, if it ever is. It might even effect your shooting with a rimfire. Why anyone would want to subject themselves to this is beyond me.
First off, I bet your CZ 550 is too long for you, and a long LOP is a sure way to get pounded by your rifle. Most adults do very well with a LOP of 13"-13.5" and a stock that is too short is less punishing than one that is too long, provided that your scope is mounted sufficiently far forward. I prefer to have my scope's ocular lens even with the rear edge of the cocking piece shroud on a bolt action big game rifle. Getting tagged by the scope mounted too far rearward on a powerful rifle is not something I aspire to and I went to custom bases on two of my powerful rifles to ensure it could not happen.
After proper stock fit, the next most important issue is your firing stance. The off-hand position allows the shooter to fire his rifle with the least amount of felt recoil . . . if he fires from a proper stance. You take a boxers stance towards the target, raise the rifle until the sights come into your line of sight, put your cheek on the stock, then bend your forward knee and lean slightly ahead. At this stage the butt of the stock must be in firm contact with the pocket of your shoulder, the looser the fit between butt and shoulder, and the farther out the butt is positioned from the pocket of your shoulder, the harder you get pasted.
I let a fellow who claimed to have all sorts of shooting experience fire my hot loaded .416 Rigby, which developed about 70 ft/lbs of recoil according to the calculator. When he slapped the trigger I could see daylight between his shoulder and the butt, and by the time I could react to stop him the shot had gone off. Lets just say the experience brought a tear to his eye and he didn't ask for a second shot.
When the proper stance and the proper hold is taken, the rifle fires and the recoil travels across your chest and down your rearward leg effectively reducing the amount of felt recoil you absorb. If firing 5 rounds is too many, than fire 3. If firing 3 rounds is too much then fire pairs. If firing pairs is too much from the off hand position, you need to reduce the load to a more tolerable level. However, many hunters take all of their African game with scoped .375 H&H bolt guns, with but a single load of 300 gr ammo, and some of these guys & gals have little shooting experience.
Once you have worked your way up to where you can handle firing 5 rounds from the off hand position, try shooting pairs from sitting or kneeling. When you can fall into a sitting position and nail a 200 yard target dead center, try prone out to 300. Not everyone can tolerate shooting a powerful rifle prone, and it is important not to overdo it, but to me the prone shot, or rather the ability to make a prone shot, denotes the dividing line between a general purpose rifle and the specialty rifle.
