I have a 870 in 20 gauge w/ 26" barrel, a 1187 youth in 20 gauge with 21" barrel, and a 1187 in 12 gauge with a 28" barrel.
The 1187 in 12 gauge has the least recoil. The 870 in 20 has noticeably more, The 1187 youth is slightly better than the 870 in 20.
If this is for hunting, I suggest the 20 gauge. A heavy gun held all day does not make for good shooting form. If this is for some range fun and a beside companion, then use a 12 gauge and purchase lower recoil rounds. For casual practice, purchse 7/8oz target loads. May not be easy to find at the store, but is very common online. There is little sense practicing with expensive buckshot. However, patterning the buckshot is important. If needed, keep the firearm loaded with remington managed recoil rounds. The most effective ammuniton is the most accurate. A lower recoil round will have a much more effective repeate shot, than those "magnum" rounds.
The bedside companion is the 1187 in 20 gauge at home. The shorter barrel and stock make is easy to manuver and mount in a hurry. IF you have little ones at home, be careful with firearms at the house. The 1187 in 20 is not easily accessible by the little ones. However, there is pepper spray in almost every room in the house. I like this one with the hand strap. Best to use non-lethal as far as your freedom from being locked up in jail goes.
http://www.cabelas.com/product/UDAP...AllProducts&Ntt=peppey+spray&Ntt=peppey+spray
http://www.midwayusa.com/viewproduct/?productnumber=482134
This is a good one to get. Has 1 less pellet for reduced recoil.
http://www.remington.com/products/a...buckshot/express-managed-recoil-buckshot.aspx
Make sure you have an improved cylinder choke, best for close ranges. Almost all new shotguns come with modified chokes. Not a bad choke for hunting. For trap shooting, the full choke is best.
when selecting practice ammunition, also take a look at velocity too. Keep in mind a proper fitting shotgun will produce the least recoil. a 5 foot 2 tall lady will not do well with a regular stock with an recoil padd making the length of pull even longer. Get a 12 gauge and put a youth stock. The factory remington recoil pads are really hard to beat. There is no sense getting anything else. Also, stock placemnt is very important on women. They have tender spots. Make sure she learns to mount the firearm properly. It will really bite her in the wrong spot.