As you may notice from my other posts on this forum I shoot Five seveN pistols quite a bit. On my weekly visit to the range I usually bring my Five seveN range gun, a USG that has a few thousand rounds through it. It is an adjustable sight model and I have it sighted in for my practice load the 40gr SS197.
When I just owned one Five seveN pistol (I currently own three), a MKII FDE with adjustable sights, it was clear to me it was sighted in at the factory with 27gr SS195. It was dead on with SS195. When I shot the less expensive SS197 40gr I found it hit between 3" to 4" low. It would take me 16 clicks of elevation adjustment to go between the two loads. I hated that because it was my carry gun and I didn't want to fool around with the sight adjustment every week because my carry load at the time was SS198, which is the same bullet as SS195 but loaded to 150fps hotter. However, they shoot to the same exact point of aim at pistol distances. So I would practice with the more expensive SS195 and leave the sight alone. That got very costly, so I decide to just by another Five seveN and sight it in for the cheaper SS197 40gr and practice solely with that gun and run a few rounds of SS195/198 through my carry gun a few times a year.
Over the last couple of years every time I would post that the 40gr SS197 shoots 4" lower 27gr SS195/198 everyone would scoff and say that is not possible. Well I have thousand of rounds through my Five seveNs and PS90. Probably somewhere around 20,000 rounds downrange. I shoot my 5.7x28 chambered guns pretty well, and practice a lot with them.
I have been meaning to do an actual test of the two rounds out of the same gun to show the difference. But every time I remembered I was at the range and only had SS197 with me. But today I remembered to bring a box of SS198 and my original Five seveN, a MKII FDE sighted in from the factory for SS195/198. I sent the target 10 yards downrange and I loaded 6 rounds of 27gr SS198 in the mag and 6 rounds of 40gr SS197. Both groups were shot Offhand at 10 yards. Here are the results, while clearly NOT 4" in every case, it is NOT far off. Realistically a good 3" difference in POI.
All MKII Five seveNs come from the factory with adjustable sights. The older USG model was available with both adjustable sights and fixed sights from the factory. They didn't make a ton of fixed sight models. My carry gun has the fixed night sights from the factory which I shoot quite well with and love for carry.
If you have a Five seveN be aware of the huge difference of Point of Impact between the different loads. There is some very serious elevation adjustment that needs to be done between the lighter and heavy loads for the Five seveN. For those of you who have been telling me there is no noticeable difference in POI between the two rounds have some practicing to do.
I now carry Elite Ammo T6B with a 32gr copper projectile. It is loaded hotter than SS198 and hit 1" higher than SS195/198. Since my carry gun has fixed sights I practice shooting 1" higher with it.