Lets see.....
Recently, meaning the past 5 years, I have taken deer with my Marlin 1894S, in .44 Mag, Weaver 2.5 20mm scope. I like the CCI GDSP 270grain
Remington 742 in .30/06, Bushnell 3 X 9 scope, 150 grain Remington SP
FN Mauser, in 7x57 Ackley, 2 X 7 Pentax, 140gr Sierra Game King
M1A, with Federal Classic 150 grain SP, .308 with iron sights
Mannlicher-Schoenauer rifle in .270, Leupold 2 X 8 scope, 130 grain Federal
The M1A with iron sights seems as good as anything else for taking deer under 100 yards.