I had a two of them, one was a series D in 222 and the other was a series E in 223.
the 222 had a horrible trigger,
the 223 was better, but still not great.
I was told there wasn't much you can do with those triggers.
I was hoping the 222 would be a shooter, so I took the rifles apart and swapped the triggers/sears.
those parts were shaped a bit different, but the holes and mating parts were the same.
After I made the swap to hopefully have a better trigger on the 222,
I noticed the location of the trigger, in regards to the trigger guard, had changed, due to the different shape.
the 223 was fine, but the 222 had little extra room after my finger was in there.
I swapped the parts back and they both got sold at my Auction last year.
Oh, both had predrilled holes in the side of the receiver and had a Weaver brand side mount installed.
NOW, a little info about that weaver side mount, the older side mounts have no clearance for a modern scope that isn't a straight tube(like an old Weaver scope), meaning the scope body is enlarged at the adjustment knobs. But the mount is easily machined to make clearance.