I share the concern about an underlying medical issue or some kind of serious malfunction in the direct impingement gas system on that AR pistol.  We have young kids (girls, too) shooting up 8-10 boxes of 12 gauge shotgun shells in a single day in practicing for skeet and during dove season.  That's 200+ rounds of 12 gauge.  They are light field loads, but still orders of magnitude more recoil than that pistol.

Weight is your friend for recoil.  Add weight to the weapon.  Wear a thick shoulder pad (they make them to wear under your shirt).   Add a recoil pad to back of the pistol stock.

Another thing:  Is it really recoil?  One can get "gun shy" from muzzle blast and start flinching.  That short barrel is going to be very loud.  Better hearing protection may be part of the solution.

Free recoil of a 5.56 on a carbine is typically between about  3.5-4 pounds. That compares to about 15 pounds for a .308 , 22 pounds for light load 12 gauge, 41 pounds for a .45-70 with medium velocity loads, 60 pounds with full "heavy" .45-70 Buffalo Bore ammo.

I'll have to agree with the others..  Something else is wrong..  I would recommend taking a few shots through another AR and letting another person shoot yours, before doing anything to it.  Seriously, just go to the range and look for somebody shooting an AR.  Walk over to them and tell them what's going on.  People do that all the time and I've traded AR's for a few rounds many times..  JMO..

I run Tubb’s CS flatwire springs and H2 buffers for the most part.
I would not describe the buffer as easy to push all the way to the bottom.

If the buffer spring and buffer setup was way too soft, wouldn't the OP start to see some contact from the rear of the BCG?...at least if the rifle was yielding the kind of recoil the OP is reporting?  I only ask due to seeing some contact issues in other threads.  I've never experienced this first hand.  It sure sounds like the OP is able to shoot big caliber, high recoil rifles in other cases, so you'd think there wasn't a physical/medical problem.  He even mentions shooting an AK.  I have a Kel Tec PLR16 and a Steyr AUG...neither have a buffer system like an AR.  Neither one of those guns has anything approaching irritating recoil with decently hot .223/5.56 ammo.

I guess I am too used to shooting my Mauser .270. Now that is recoil. One of the things I like about my AR is a lot of hitting power with hardly any recoil. If it were bothering me I would for sure see a doctor. Something is wrong.

This issue of recoil with a 5.56 AR hurting this guys shoulder is saddening. I agree with many of you that there has to be an underlying physical issue. For me, even shooting my KAC SR-25 does not bother me. My Garand has a little bit, but I can put about 40 rounds through it before it starts to bother me. I was shooting a FR-8 the other day that I sold a guy. Now, that has some recoil, as does my Mosin M38. Recoil from a 5.56 AR should never be enough to cause anyone any pain. As some of you suggested, I, too, would recommend seeing a doctor to see if there is some sort of physical issue.

The BCG and buffer bottom out in the RE otherwise the weapon would not lock back on the last round.
Going to a heavier spring will certainly change the OP’s perception of what the recoil feels like.

Even if the gun is seriously overgassed, it shouldn't be causing lingering pain or bruising after only 60 rounds. I could understand that happening shooting .300 Win Mag, but not 5.56 in any flavor. Most 8-year-olds can shoot 5.56 without bruising.

Turning down the gas with an adjustable gas block should help, but OP should consult a doctor.

I agree with the above. If another shooter has the same problem you know it's the ArR If not then there might be a medical condition you are not aware of or something in your shooting technique . At least you will eliminate one of the variables. 60 rounds of 223/556 should not be causing you the pain you are experiencing.

Neuton's second law of physics - Force = mass x acceleration

a bolt gun 556 and a AR with an extremely weak spring are not at all the same as far as recoil, if his spring is really weak and has no resistance, the BCG and buffer(mass) will be driven back much faster(acceleration) causing more felt recoil(force)

I have seen and felt ARs with excessive recoil (comparatively) due to really underpowered springs, with an unpadded stock I could see how it could cause some discomfort after 60 rounds.

The OP has stated he shoots larger caliber rifles with out a problem, so unless he's lying or delusional, there is an issue with his gun.

Nevermind