I have been playing around with my G20 a lot lately and am quite pleased with my results with the VV N105 powder. Only downside on this powder is that the velocities Vihta claims to get in their manual are way over exaggerated.
Vihtavuori doesn't show any data for the 170 grain Fiocchi TMJ bullets I bought, so I started at their max load for a 180 grain bullet (knowing a 10mm max load from their manual is not even close to max) and worked my way up. The 170 grain bullet with 10,5 grain of N105 was my starting load and this one didn't felt too hot. So I moved to 11,0 grain of N105 and this load seems to be a good one. Cases fly pretty far with my stock 17lbs recoil spring (easily up to 15 ft), but don't show any signs of overpressure. Accurcay is very good too, at 50 meters (55 yards) I shot 84/100 yesterday on a standard olympic pistol target, I've seen guys doing a lot worse with a rifle at this distance
I'm guessing this load will do about 1250 fps, but I could be off by 50 fps as I have no chrono and none of my shooting buddies have one either. COAL is 1,255 and I use a Magtech LP primer in my Starline cases.
I also bought the last batch of Sierra 190 FPJ Tournament Master bullets my gunshop had in stock. I got to buy them at a good price I think: € 16,50 for 100 bullets, bought all 3000 of them
Sierra stopped making those 190 grain bullets in 2009 and since a good quality FMJ .40 bullet in Belgium is a hard thing to find I decided to buy all of them, sort of like an investment for the future
Sierra now only makes hollow point bullets in .40 and in Belgium we cannot buy these in handgun ammo (one of the very few things we are not allowed to buy).
I use these 190 grain Sierra bullets with 10 grain of N105 and this feels like a true 10mm load. I cannot chrono these loads, but I guess I get something around 1150 fps. These are very solid bullets, well construced, with good accuracy. If I were living in a bear-populated region I would use these bullets for protection without a doubt as penetration will be superb.