"In WWI you needed to put rounds on enemy trenches that may be 2000 yards away. The M1903 would do that, the M1903A3 wouldn't have been able to (accurately), that's not because the 1903 was more accurate then the 1903a3. It was the sights. The sights for the '03 were good to somewhere between 24-2500 yards (depending on the sight model) where as the 'A3s sights are only good to 800 or so yards."
Putting fire on the trenches in WW I wasn't done with rifles and volley fire sights. It was done with machine guns and artillery.
Volley fire as a concept was for long-distance fire against clustered groups of infantry.
The entire concept of volley fire had been born in the middle to late 1800s, and it, as a concept and as a practice, DIED in the trenches of the Western Front.
One of the first modifications the British made to the SMLE during the war (but after the armies started digging it) was dropping the long-range volley sights.
The also stopped teaching recruits how to volley fire as a unit.
I may be wrong, but I don't think, even in the early days of the war, that long range indirect volley fire was used once.
At Mons it was long-range direct fire.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.