Some additional notes.

Sighting distances. Sighting any handgun in at a short distance such as 25 feet isn't an optimum choice. Every handgun that I know of uses sights that lie above the barrel. As a result of this, adjusting the sights for a short distance will cause the line of sight and the barrel axis to converge and coincide at the distance that it's been sighted in at. When you sight in at a short range that angle of this convergence will be higher. The result is that the gun will shoot high at longer ranges. If you assume there is no bullet drop and the offset for the sight line is 3/4 inch, at 25 yards the gun will print 1.5 inches high. Now flip the distances and sight the gun at 25 yards and you have a lower angle of convergence in the sights. Make the same assumption about bullet drop and the maximum deviation of the sights will be at the muzzle and will equal the offset of the sights to the barrel. At 25 feet, the deviation will be 2/3 the offset for the sight, or about 1/2 inch. I'll grant that in a handgun 1 inch really doesn't matter, as long as your using the iron sights. However, if you employ a rail mounted sight, these effects can add up to a significant error due to the much larger offset for this type of sight.

Bore Transit Recoil. It's been mentioned in previous posts that bullet weight and velocity have a distinct effect on the point of impact. The reason for this is that recoil forces start the barrel moving upwards as soon as the primer sets the powder burning. Whats not been mentioned is that gyroscopic precession will also start driving the barrel in a horizontal direction. Fortunately, precessive forces show a much lower effect than recoil forces but with a riight hand twist the muzzle will tend to drift up in a leftwards motion. In my experience that line of motion will be about 15 degrees from the vertical, however that angle will vary with the rifling and speed of the bullet and it's weight. On a side note, a slightly "overtorqued" barrel will tend to compensate for the effect of precession.

Now back to Bore Transit Recoil. As noted that barrel starts moving as soon as the bullet starts moving. The amount of movement of the barrel while the bullet is transiting the barrel will "steer" it's flight. Double the length of the barrel and you will see a doubling of the time that the bullet spends in the barrel. As a result, long barreled handguns will be much more sensitive to the effects of recoil management. They will also be more sensitive to the effect of changes in bullet weight and velocity. As a rule, if pressure is maintained as a constant, the heavier a bullet is, the higher it will print because the slower moving bullet spends more TIME in the barrel. However, with the disparity between the power of the 38 spl. and the 357 Magnum, these rules break down. While I don't think that this change in power level will add up to an 8 inch error at 25 feet, I do know that there will be a distinct difference in the point of impact. My personal experience with my 620 is that at 30 feet sights that are perfectly zeroed for a 125 grain 38 spl. will require a 6 o'clock hold for a 158 grain 357 Magnum clocking 1250 fps. That is about a 2 1/2 inch difference in POI. Factor in the effect of a 6 inch barrel versus the 4 inch barrel on my 620 and we are probably talking about a 4 inch difference. However, recoil management does vary with the individual because some are very firm during recoil and others shoot a bit more freely. Bottomline, the POI difference between a 38 spl. and a 357 Magnum can probably be predicted to fall within a range of 1.5 to 6 inches at 30 feet.

Point is, it's the HUMAN element that has the greatest effect on how well a gun shoots in almost every case. In addition, increasing the length of the barrel in a handgun actually magnifies the effect of the HUMAN element instead of making it easier. I'm actually a pretty decent shot with my 620, especially with a 38 spl. or 38+P. However, with the Magnums I am still struggling a bit with group sizes. I'm also still struggling a bit with my 6 1/2 inch 610 due to the long barrel, I've had days when I can group 2 1/2 inches at 100 feet but generally a 4 inch group at that distance is a good result for me.

Bottomline, even the "puny" 357 Magnum is a caliber that takes a lot of practice to master. Don't blame the gun, it's highly unlikely the gun is the problem. Blame the person pulling the trigger and have have that person spend more time shooting. I'll also note that experienced Magnum shooters are a rare sight at most ranges today. So handing that gun off to a friend and having him "test" it isn't a valid test unless that buddy has previously demonstrated a high level of skill with this caliber. The 357 Magnum is NOT an easy caliber to master and it takes time and a lot of practice. You also have to pay very close attention during that practice because the 357 Magnum is a Flinch builder par excellance.

PS; one tip for gaining skill in feeling a flinch, or what I call "listening to your body". Short load the cylinder and give it a spin with your eyes closed just before closing it. If you've built a flinch, as soon as you hit that empty cylinder you will see it very clearly. While snap caps can be used, an occasional dry fire on an empty chamber won't do much harm. If you have snap caps, use them, however if you don't have any, don't be afraid of an occasional short load, it takes thousands of dry snaps to do any real harm.