It is impossible to stop recoil.
Give it a good cleaning, check the recoil spring.
Browning did not invent the 7mm
There are several 7mm cartridges out there.. the basic 7x57 will have less recoil than the .30-06, but there are cartridges marketed as 7mm which produce significantly more recoil.
You will have to call Browning with the serial number.
Browning does not make a M70 semi auto 7mm nag
You can never stop recoil. You can reduce the felt effects, but, the recoil will still be there.
1966.
A call to Browning for a manual or a trip to a gunsmith is in order.
Best left to a gunsmith.
Factory or aftermarket?
300-800 USD
Good rifle