Hi-Lux Optics currently offers three period-correct models that would be at home on a M1903A4 and the USMC M1903A1 sniper rifles.
Lockhart Tactical Raven Modular Semi-Auto Rifles - Hi-Lux Optics 6 X 3/4 Malcolm Telescopic Rifle scope 32 Long With Mount
Hi-Lux Optics Malcolm 6X17 Long Rifle Telescope, 30 in. Long, 3/4 in. Main Tube, Fine Cross Reticle at Tractor Supply Co.
hi-lux Archives -The Firearm Blog
Hi-Lux Optics M82G2 Vintage Rifle M82G2 2.5 x 7/8 Tube Reproduction Scope, Black : : Electronics
Vintage Gun Scopes, 51% OFF
Hi-Lux Introduces $549 Unertl-Type 8X 'Vintage Sniper' Scope « Daily Bulletin
M82g2 Scope Deep Discounts
Leatherwood/Hi-Lux Optics: 2012
Malcolm 8X GEN II Vintage Sniper Competition Scope (Hi LuX)