Reddit mentions of Mauser Stripper Clips 10CT 6.5x55mm 38,94,96 & 30-06, 1903, 1917

The 5-groove barrel is the original barrel; they (and the 1903's) received 2-groove barrels when they were rearsenaled. Standard .30 cal cleaning: bore brush, cleaner, patches.

Get yourself some Stripper Clips and have fun running mad minutes.

Be sure to take the bolt apart and give the internals a look. You'll find a m6 fender washer helpful for not munching your fingers.

It always gets hard dating these kinds of things...but according to this site which not only lists serial numbers but the number of actually produced firearms for the month - the number in process and more importantly the number accepted by ordinance approval it sounds (looks) like its possible for a rifle to be started in one month and then finished (or accepted) in the next as there is constant carry over during all the production.

Of course its also possible someone took off a closely matching barrel from another receiver and put it on yours. Either way I would check the amount of throat erosion and of course if the bolt head spaces into the barrel. If the rifle is solid and that all holds up as long as the price is good it shouldn't be an issue as it probably is an all original (or at least I cant find anything that would say it isnt)

Theyre great guns and if you want a tip buy some of these 6.5mm Laddram Clips as they will work in an 03 as stripper clips (will ping out after loading/as you close the bolt) its impossible to get original 03 stripper clips as they were two parts (brass and steel) and once the rounds were loaded the two parts would separate and really were one time use, ive been using these same couple mauser clips for a few years now over and over no issues, good luck!

edit just saw the price on those 6.5mm clips, when I purchased them they came in a 40 ct milsurp box (in total about $35) so shop around as they aparently now only give you 10 for $28.50 which sounds steep to me.