ok....think I found my answer.....went to Chuck Hawks tables for both rifle and shotgun.....here is what I found...

listings included 12 ga 3" and 10 ga 3.5".... and the rifles included a significant aray of calibers.....without a 12 ga. 3.5" listed I had to interpolate an answer based on the provided data.... recoil was identified as energy in foot pounds for both shotguns and rifles....rifle weight was also identified.....data breakdown is as follows....

12 ga. 3" was through a 8.75 lb. gun shooting "1 7/8 oz" of shot at 1210 MV ---- recoil energy is 54 ft. lbs

10 ga. 3.5" through a 10.5 lb gun shooting "2 1/4 oz" at 1210 MV, also ----- recoil energy listed as 63 lbs

I would guess that the 12 ga 3.5 would be at least toward 60 lbs, if not slightly over

now the interesting part: expressing the rifle weight and ft lbs. of energy yields some interesting comparisons

.300 Wby Mag - 150 gr @ 3400 MV through 9.25 lbs of gun weight ---- recoil energy is 24.6 lbs
.340 Wby Mag - 200 gr @3100 MV through 10 lbs of gun ----- recoil energy of 29.6 lbs
.375 H&H Mag - 270 gr @ 2690 MV through 9 lbs of gun ----- recoil energy of 36.1 lbs
.378 Wby Mag - 300 gr @ 2900 MV through 10.25 lbs of gun ------ recoil energy of 71.1 lbs
.416 Rigby - 400 gr @ 2400 MV through 10 lbs of gun ---- recoil energy of 58.1 lbs
.458 Win. Mag - 500 gr @ 2100 MV through 9 lbs of gun ---- recoil energy of 62.3 lbs
.460 Wby Mag - 500 gr @ 2600 MV through 11.25 lbs of gun ----- recoil energy of 99.6 lbs

These are very interesting data points for those who have issues with putting a heavy caliber big bore to shoulder but at the same time will put a big 12 ga. load to shoulder on a bench when we pattern our shotguns for spring turkey.....I for one put a new BPS 12 ga NWTF 3.5 to my shoulder this way a couple of weeks ago to get ready for spring gobbler....patterned the turkey full choke at 15, 25, 35 and 45 yards for two different federal 3.5" load types....had a nice case of recoil rash on the shoulder....was enough to prompt taking it to the gunsmith to have a new kickeez installed to replace the factory pad.....but all of this was instructive to me....I have never ventured past a Wby .300 Mag in centerfire....and the notion of putting a Brown Bear load up, not to mention a load for African Big Game, was something that just never held much attraction....so these comparisons are interesting and informative....hope they are to you as well

WOW
VERY interesting.
Strange that I shoot my 12ga 3 inch all day but hate shooting a 300 magnum.
Must be the noise factor

Noise is probably part of it, but I think there's a difference in the feel of the recoil also. For me, at least, the 12 ga. recoil doesn't seem quite as sharp. That is, it seems like it's spread out over a longer time, though I'll admit that it's probably like 4/100ths of a second instead of 2/100ths of a second. Still, it just doesn't feel as much like a sudden hammer blow, but more like a hard shove.

I can agree with the notion you bring up.....one missing component on the shotgun table was recoil velocity.....velocity was a column on the rifle table that sat along side of the recoil energy data....the shotgun table had no mention of it...

and as the rifle table explained, velocity was more about the sharpness of the recoil.....wish that data was included for the shotguns to fully compare the feel factor....

still, what was fully compared was more than a little telling.....when those 3.5's light off, you know it.....and now I can respect the situation all the more.....

regardless, a good recoil pad and well positioned butt along with a "past" pad make a lot of sense when at the bench testing....

What you feel sitting in a duck blind or goose pit when you have a death grip on the gun is a little bit different than what you feel with that rifle at the bench. However, lay that shotgun up there on the sandbags and gently squeeze off five 3.5" rounds while barely supporting it with just your trigger hand and it will feel just as enjoyable as that 375 H & H does.

SH

I use a 12ga Remington 11-87 SP for duck hunting and can shoot 3" magnums all day in that thing with no complaints from my shoulder. But then again it's a gas operated semi-auto, felt recoil is typically much less with these.

Sporting Clays I use both a 12 ga Franchi Alcione Field Grade O/U and a Beretta 686 Onyx with light target loads and after 100 rounds I'm a bit sore. Use the same guns for upland hunting with heavy game loads 2 3/4inch 3 3/4 Dram 1 1/4 oz shells. Recoils is pretty stiff with these. Those same loads in my Remington are pretty soft.

It's the same with rifles, an advantage of gas-operated guns is less felt recoil.

The higher your weapon is pointed in the air, the greater the recoil, or am I wrong?
Seldom would anyone have cause to fire a heavy calibre rifle upwards at say 45 deg angle, but it happens all the time with shotguns.
That would definately make a difference on the poor shoulder I would think.

It sure does!!!!!!!!!!!!