I only use cheap ammo like PPU soft point, AE 150g so I never do any better than 2-3 in at 115 yards, plus I'm not a good shooter anyway.
I don't think you're doing anything wrong. 2-3 is about what one should expect from the -M with regular ammo. Try some PPU 168 gr. About the cheapest factory new match ammo around.
Fool-proofing serves only one purpose: identify bigger fools.