shooting
I would just have to shoot the rifles for a zero check, after a swap, and these days, season after season, that could get expensive. Get another scope.
Regards old USA Redfields, I'm talking scopes that are 30 yrs old, maybe more. I have 3 that have seen use in recent seasons. Two have been back to the "Ironsight" people in OK for rebuild about a decade ago. However, only one is on active duty at present, and that is on a rimfire that does most of its work in the bright of the day. What I have noticed was those old scopes were just not as bright on PM hunts in the last 15-20 minutes of the day, often when game/deer showed up. It may well be that my 57 yr eyes got to the point where I noticed it more, but none of my 3 vintage Redfields are as bright as newer scopes of equal quality bought in the past 10 yrs or so.
I had occassion to prove that just today. I pulled a vintage 2-3/4x Widefield from a carbine, and put on a Leupold 2.5x of more recent mfg. I then fired about 10 rds to re-establish zero. It was late in the PM, very cloudy and overcast, flat light. As both scopes were on hand, a comparison was easy. The difference between the old Redfield and the newer scope, in brightness and clarity, was very obvious.
Point being, you can buy a lot of scope these days for $200 bucks or so. You get a glance through a current scope and You may find your old Redfield on its way to retirement too.