In every case ---- the 12 gauge has much more recoil. This is especially so if you are shooting the heavier 2 3/4" or 3" Magnum loads. If your 12 gauge shoots the 3 1/2" shell , then even more so.
I have attached two (2) Recoil tables from ChuckHawks.com.
The 30-30 has recoil in the area of about 11 or 12 ft lbs.
The 12 gauge has a minimum recoil of around 17 ft lbs. for light "field or target loads" and goes up to as much as 54 ft lbs, for the big Magnum loads.
The 12 gauge definitely has much more recoil in all cases.
The weight of the gun has a lot to do with the recoil as well. The heavier the gun, the less recoil. So a heavier gun will recoil less. If you are concerned about recoil, the lighter 12 gauge 2 3/4" Field Loads (1 oz or 1 1/8 oz of lead shot) will recoil much less than the normal 12 gauge loads.
A couple of "Recoil Tables" from Chuck Hawks are attached below:
Shotgun Recoil Table below:
Rifle Recoil Table below:
Like hitting a golf ball with a driver; then hitting a 16" softball with a driver. Not the same.
12 gauge is a good bit more,considering a 30-30 has no noticable recoil.
Neither one has much,but then again I've shot them both just about all my life.Pick them up and give it a try I promise neither will break a shoulder.
Shotgun and rifle recoil differ greatly. Shotgun recoil= sharp,quick punch. Rifle recoil=blunt,longer,push. They are not noticeably similar.
It depends on a number of factors, including the weight of both guns, the recoil pad on each gun, and what load is being fired. Also, on the shotgun, the action type will make a big difference. Gas operated semi autos kick way softer than pumps and break open guns. Comparing the average pump shotgun to the average lever action 30-30, when firing light target loads in the shotgun, the recoil will be pretty comparable. When firing longer or heavier loads such as slugs, the shotgun will have more recoil.