The Lyman Alaskan is and was a highly respected all weather scope, and the M81 and M82 were US Government spec scopes that were basically clones of the Lyman Alaskan with differing cross hair or post configuration.
These last two scopes were also used on the M1C and M1D Sniper rifles to great effect.
The test firing report I mentioned gave a few other comparasions, the 03A4 was the lightest of the Sniper rifles tested at 9.5 pounds, the No.4 (T) was the heaviest at well over twelve pounds.
Since of all the sniper rifles tested the scoped 03A1 was the only one that grouped well enough to make consistent hits at extreme ranges, with the 03A4 coming in second only to the 03A1, the accuracy advantage clearly lay with the Springield. I doubt you'll find many who would consider extremely good accuracy and reliability of the rifle to hold its zero after months of combat in moist tropical weather to be unimportant in a sniper rifle.
The earlier non sealed scopes were used because they were available, when better scopes became available they were used. Theres no sense in bemoaning the fact that a better scope was not available in quantity till later in the war.
Had the US adopted any other rifle for sniper purposes, as they had considered a purpose built Model 70 similar to the rifles later used in Vietnam, they would still have been limited to the scopes available in quantity at the time.
The 8X Unertl was also used on the early Vietnam era Model 70 sniper rifles, and once again to great effect.
That would be a difficult claim to defend, since the 1903 rifles were always known for superior long range accuracy compared to any other rifles fitted with milspec barrels, none of the sniper rifles in use by other countries used extra heavy profile target grade barrels with the exception of Australian No.1 rifles with the HT target barrels. The Springfield barrels look plenty heavy to me, and beat the pants off all comers in the 1,000 yard matches with the supposedly too delicate issue iron sights.The springfield was a good service rifle but was never designed for long range accuracy with it's comparatively short , thin walled barrel ,
A dedicated sniper rifle built using a commercial action and heavy barrel would be practically the same as the Model 70 rifles used in Vietnam. Certainly a fine rifle for the purpose,but at the time issuing a rifle such as this would have had a number of drawbacks, supplying replacement parts for a non standard rifle and added training for armorers in servicing what was still a commercial sporter action, addition to inventory of replacement stocks and developing bedding techniques for that specific rifle, etc.
More emphasis has been placed on long range sniping since the mid Vietnam era switch to purpose built sniper rifles, and for the most part the modern versions of the old time sporters have benefitted from advances in barrel making technology. Since no other rifle caliber bolt actions remain in active service, theirs no supply line conflicts as there would have during WW2.
The post WW1 Scoped P-14/No.3 (T) was considered to be a superior sniper rifle when compared to any of the Lee Enfield actioned sniper rifles, but maintaining a limited issue rifle that had all but outlived its supply of replacement parts with no new parts being manufactured resulted in it being a stop gap measure to do the job until the No.4 (T) was developed.
The 8X power Unertl scoped 03A1 was capable of making hits consistently at ranges where the competition were neither accurate enough or in most cases did not have optics suitable for extreme long range sniping.
The 03A4 was a lighter and handier rifle than most of its competition, the low magnification of scopes used on this rifle put it more in the class of a designated marksman rifle , a role the revamped M14 rifles are often used for these days. The rifle was certainly capable of making headshots at ranges where a one shot kill with the rifles of the competition was problematic.
As I've said before I personally don't have much interest in the 1903 Springfield or its variants.
It does have tremendous historical interest, and attempts to dis all versions of the rifle based on the tiny fraction of one percent of the rifles that failed due to brittle recievers has sparked my interest. That and the too often overblown claims made in defense of other bolt action contemporaries which had their own shortcomings.
All were adequate for the purpose they were put to, and all aquitted themselves well in the hands of skilled marksmen.
I'm waiting to hear a good argument that greater and more consistent accuracy was of no particular value in a Sniper's rifle.
One might argue that the low 2.5 power scopes limited the useful range of the 03A4, but then again hunters these days often pick a lower power setting for variable scopes to allow for a better sight picture in low light situations, such as mornings, evenings, overcast skies ,and under a forest canopy where much infantry combat took place both in the Pacific and in the forests of Europe, not to mention the deep shadows of an urban battle zone.
Personally I prefer a 4X scope as a minimum, but the scopes chosen for the 03A4 were very compact, weren't set high enough to prevent snuggling into the butt stock, and less likely to become hung up on vegetation.
Scopes of the same general type were certainly well suited to use on sporting rifles, where quick target pick up and ID in variable light conditions meant the difference between success or failure, and possibly life or death if the quarry is a carnivore.