My son now has ownership of my No.4 Mk 1 Long Branch Enfield, re-stocked with a walnut sporter stock by Elwood Epps in Ontario, Canada. This isn't a heavy rifle and having seen some .303 Enfields in a commonly available aftermarket synthetic stock, my son's rifle is about on par with them, weight-wise.
One of the joys of that rifle is that feels light on the arms and light on the shoulder, but it isn't so light that it is hard to rein in whilst shooting in the field. In spite of the long barrel, it still has a handy, dynamic feel. It points like a shotgun. I wouldn't want to mess that up by adding weight to it.
It originally had a solid buttplate when I bought it. Felt recoil to me was less than my Marlin 336 in .30-30. Not a lot less, but less. If one can handle the recoil from a .243 in a standard weight sporter, I should think one would have no trouble shooting a .303 well, even a light six or seven pound one.
The rifle has a Limbsaver pad on it now. With that, felt recoil is nill.
Oh, and another thing I like about the .303 is the report. It is kind of distictive to me -not a thunderous roar or sharp crack, but a mellower boom.
I'm a huge fan of the .303 because it is plesant to fire but has plenty of downrange oooomph for taking game larger than deer. My son has been shooting it since he was 11, and a slightly built 11 at that. We were out at the range one day and this little 9 year old girl wanted to try it. She shot a whole 10 round mag full with no problem. She'd have probably shot it even more if we'd have had more ammo on hand.
I could go on and on.... But that sporterized Enfield I gave my son is one of my favorite recreational target shooting and big game hunting rifles of all time. Pleasant to shoot, but very powerful, and accurate enough to be fun on the range.
JP