So, a 4+" group with a M41 at 25yds? Pretty good. Better than most can do. Some constructive criticism though...
1. Limit your groups to 5 or maybe 10 shots. Not only more standard, your 4" will likely shrink a bit.
2. Convince yourself that there's no such thing as a "flier". Calling your shots is an important skill to develop, but even a called errant shot counts. If it's truly not representative of your skill level, your average 5-shot group size won't be affected much by it, so record it, but don't sweat it, either.
3. My benchmark for good, but not excellent shooting under these conditions (25 yards, unsupported, 2 hands) is an honest and consistent 3" 5-shot groups. "Honest and consistent" are important qualifiers, implicitly discussed in #2. Your M41 is a fine pistol. With it's preferred ammo, 3" or better is do-able, IMO.
4. Consider using an actual NRA 25 yard pistol target, B-16 or B-8.