On the range yesterday, one of the shooters on another lane had bullets striking the target side on, keyholing. I suggested his bullets were clipping the grass before striking the target, but he refuted this. (We were shooting at 100 yards from fire trenches, not raised berms.)
He was using factory loaded PPU, he said it was 174g FMJ though I didn't inspect the box. His rifle is a well battered 1943 No 4 that had probably been round the word twice and fought in every campaign. He thought the rifling looked good: I thought it looked eroded but as I didn't have my bore scope with me, I was only able to use the Mk I eyeball.
So I fired ten rounds of the PPU through my 1954 No 4. (This is one of the rifles from the 'Irish contract', one of 50,000 sold to the Irish goverment and mine probably never left the armoury.) In my rifle the PPU factory shot about 18" higher than my handloads with Hornady 174g FMJ-BT. They formed two groups, one of five rounds and one of four (one shot went just over the target board), both groups were under 2", all bullets had struck nose on. Nothing wrong with the PPU ammo, then, must be his rifle.
I then fired ten rounds of my own handloads in his rifle, two groups of five. Again, they formed two groups of 2" (OK, one errant round went out ot about 5", I probably snatched the trigger). So, nothing wrong with his rifle.
So why was his rifle keyholing the PPU bullets? I still say he must have been clipping the grass en route.