Can one build a resistance to rifle kick?

Shoot lighter and slower loads and have the stock tweaked if possible to make it fit. You will never become "used to it", the opposite will happen - you'll develop a serious flinch and really have trouble shooting it

that is a very short somewhat light weight bullpup shotgun.......the laws of physics are already working against you if you are looking for a soft shooter in a 3" chambered 12.......

if you can't modify the gun or loads, then modify yourself.......use a PAST brand recoil shield......you might be able to at least tolerate it for a few rounds..... https://www.midwayusa.com/product/1002531259?pid=699899

One thing that would help if you're not already doing it is hold it tight to your shoulder. If it's loose and is able to move around you will feel more recoil. Other than that like deputy said it's a small light 12 gauge which makes felt recoil increase. Heavier guns and guns in semi auto will feel better on your shoulder as a general rule. Caliber/gauge also plays a big factor or course.

Look at having a recoil pad added to the butt stock of your long gun. Preferably one that is 1-inch thick and high quality, such as, Limbsaver, Pachmayr, etc.

Here is one specifically made for the Kel-Tec KSG .......

https://www.amazon.com/Kel-Tec-Shot...dr-20&linkId=b3706c57632bd914f6764c55d61ba30a

Your shoulder will toughen up a bit and you won’t bruise anymore but like the others have said physics aren’t deniable. You picked a real kicker for your first long gun.

deputy said:

.......use a PAST brand recoil shield......you might be able to at least tolerate it for a few rounds..... https://www.midwayusa.com/product/1002531259?pid=699899

Click to expand...

I'll second that. PAST shields WILL definitely work!
I've used both the strap-on magnum and the field recoil shields.

I just use the PAST field recoil shield for shooting my 8Lb 458WM.
Works great - All I need. Also like the way the field shield fits under even a light shirt, too:
https://www.midwayusa.com/product/1002530831?pid=680235

It would not hurt to increase in exercising and building your body up a bit, but that in itself will will not solve the problem of a heavy recoiling gun. As has already been suggested, insure you are holding the gun firmly to your shoulder (very important) to manage the recoil into a hard push instead of a sharp kick. A good recoil pad will also help. I agree with the PAST Shield being pretty effective. Let the bruising heal up, then go and work at these things diligently. If you don’t practice a firm hold against your shoulder, the shield is not going to help much. And then focus on your aim and trigger pull once you master how to hold the gun to minimize the effects of recoil. Otherwise you will develop a flinch that will constantly ruin your aim.

Recoil pad on butt stock and pad sown into shooting/hunting jacket is what I used with shot guns and big bore rifles.

Wow, lots of insight here, huge thanks to al of you! Will be getting that extended butt pad as well as the butt and shoulder pads. Also will be working out those muscles a bit more and keeping the butt tight to my shoulder when shooting.

I definitely agree with the idea of putting a Pachmayr Declerator recoil pad on it! When I bought my Ruger No. 1 Tropical in .458 Winchester Magnum, I had my LGS put a Pachmayr Declerator pad on it before I fired a single round through it. It's a 9-pound gun but I was loading 500 grain bullets to 2,150 fps for about 5,100 ft-lbs muzzle energy. Even though this is a heavy gun, I'm sure that the recoil is as much or more than your shotgun but, that pad tamed it right down. In fact, it was a "hoot" to shoot.

As I shoot M44 Mosin and a Budapest M95 I have learned to roll with those recoils, Tolerance/Tolerated, NAH, NOPE, I had to learn to take the F out of way (Aint No F In way) I just know s#$% gonna hurt and roll with it