Any information anyone could give me on this model would be very helpful. It has the mounted site which goes up to 20. The bolt on the side IS a side bolt (it does not curve down, but is perpendicular to the barrel, which is 23', I believe). Does the 1900 take the same cartridge size? I have not found a clip for it (yet). Apparently the 1903 model was the production model, and took 6.5x54 cartridges. I did some searching, and found little info on this particular rifle. One in particular is a Steyr rifle, stamped 1900 on the side, and a serial number and LD 21 on the top.
That said, I've inherited a steyr 1900 rifle from my father (he passed away two years ago, and I am just now getting around to sorting through his firearms and loading equipment). First, apologies all around I am not very knowledgeable on firearms, and don't know a lot of the terminology.