The worst positions for felt recoil are from a prone position, followed by shooting from a bench.
Your body is in a position where it can't move enough to "deflect" recoil, so it "absorbs" the shock.
Shooting with the back of your shoulder against a tree or some other solid object may be worse?
I will admit, I'm recoil sensitive. There are some rifles I just won't even consider shooting because of it.
Lots of good information for reducing felt recoil in the above posts.
Many of my rifles have steel butt plates and IMHO, they don't hurt any more to shoot than others with soft recoil absorbing pads.
If your body is to tense while shooting from any position, felt recoil will be an issue for most people.
I know a 5 foot tall lady, who is close to 65 years old, who shoots a 338 Win Mag, with factory loaded 225 grn ammo. She might weigh 100 pounds, in soaking wet clothes.
Watching her shoot that rifle is painful to watch.
In her words, she "rolls with the recoil" and it's very obvious watching her shoot from the bench, prone or standing.
It looks like she's being pushed, but it's just her body moving to deflect the recoil, rather than absorbing it.
I didn't notice anyone mention "stock fit"
Stock fit is very important when it comes to how your body will "absorb or deflect" recoil.
I find firearms with "to short" for me stocks, produce excessive recoil, and the same goes for stocks which are "too long"
Stock fitment is very important when it comes to recoil.
Some military rifles, such as the Lee Enfields can be had with butt stocks of different lengths. Most others are just "one size fits all"
I don't know of any Mosins, other than one offs, which have short, standard or long stocks.
OP, if the stock on your Mosin doesn't fit you, then as mentioned above you may need an extension, such as a slip-on pad. If it's too long, you're kind of out of luck, unless you are willing to destroy collector value by cutting and reforming the butt.