Bullpups harder to shoot...now...that's funny.
I bought my first "real" bullpup'" (Steyr AUG) back in the mid 1980's. Prior to that, I had a couple of more normal sized rifles. I had NO problem going from a full sized HK 91 (.308 cal) to my little AUG (.223 cal.) and back, in the same morning. A heavy kicking, long gun, to a very light kick, short gun, and still hit what I was aiming at..! So...what's the difficulty ? It's ONLY...in ones head. If you don't think about each gun and its differences, and "let yourself adapt". While sure, they are different, after the first or second shot, it SHOULD be of no consequence.
So, back to the Reign. I have the .22 version. I also cut the barrel down to bring the Reign into the realm of a more proper length Bullpup, in my garage. Granted, I do have a short "range", about 18 yrds. (about a foot short), but my hacked up Reign, offhand shooting can produce 1-1/2" groups easy enough. 2" if I'm just shooting in general, but less if I concentrate on what I'm doing. Before I cut the barrel, my accuracy was about the same, no notable change after the cut-off wheel. I don't use calipers to check the spread, I'm almost 70yrs old, and am "way" past (that stopped at about 20yrs old) trying to impress anyone but myself. I just enjoy the shooting and keeping the holes in the targets as small as possible. I'm shooting both JSB 18.13 gr, and JSB 29.39gr. pellets. Just a tiny difference in point of impact.
I like the Walther Reign, feels comfortable at the shoulder, if a little front heavy. I swapped the cocking lever to the left side to make my right handed shooting more comfortable. I shot it yesterday after putting a different sight (red dot) on it. It took a few shots (about a 4" group!) to bring it back to where it should be shooting. I like the smaller "pistol" sight I just put on it better than the larger than the more rifle sized sight.
Anyway, yes, you should be able to shoot 1-1/2" groups at 20 or 30 yrds easy enough. Especially off a rest if you are using one.
Mike