I guess, you are historically confused. At the time of the introduction of the Manlicher 88/90 into military service, Hungary did NOT exist as an independent country. It was a part of the Austro-Hungarian Empire. So what “Hungarian contract” are you talking about?
Having said that, there was, indeed, a contract between “Österreichische Waffenfabriks-Gesellschaft Steyr” (Austrian Armament Plants Co-operative Steyr) which produced weaponry for the Austro-Hungarian Empire, and the Bulgarian State (Principality of Bulgaria). Bulgaria defaulted on the contract and Steyr sold a large number of the M88/90 rifles from that contract to Siam in the 1890s.
Personally, I don’t see any evidence that the rifle is somehow related to that “Simese contract”. The marks on the receiver: OE WG, mean “Österreichische Waffenfabriks-Gesellschaft”. They are pretty normal. Nothing unusual here.
A weird mark on the stock looks to me like an ornamental “CK” initial, perhaps the name of a soldier who carried the rifle? Although, I’m not absolutely positive about that.
Before you start lecturing me on history please make sure you understand the history you are speaking of. Yes Austria-Hungary was a country, however look at the compromise of 1867 and you will understand that Hungary and Austria might have had the same monarch however they were separate countries under the same Emperor. Some stuff they had common control, and others were maintained separately. One of those things that was partially split was the military. There was a common military (the K.U.K), the Austrian military (the K.K.) and the Hungarian military (the Honved regiments). This is also why you will find B-P 'crest' date marked M95s and M88/90s as they were accepted into the Hungarian military.
However relooking I do see that it is a defaulted Bulgarian contract (my mistake, it is hard to find any information on these rifles, let alone such a small number of rifles like the Siamese ones), which actually strengthens the argument that this is a Siamese Mannlicher due to the fact it has the bolt handle with a stamped serial number which was something that was specified for the Bulgarians (Austro-Hungarian M88/90s have unserialized bolts, this also applied for the M95s as well). Seeing as it has the stamped bolt (zooming in I was able to read a '80' and seeing as the serial number on the barrel is 8065, I am fairly confident it is the serial number of the rifle), lacks the Bulgarian acceptance mark (a small lion on the receiver), and has the odd markings on the stock and receiver (OEWG is just the markings for Steyr as you have mentioned, however those were not the markings I was speaking of) I am fairly confident that this is a Siamese M88/90.
The markings on the stock I could discount if they were alone as soldiers from that area loved to mark the stocks with their initials (I have a Bulgarian M95 in 8x50r with several initials on it), but the markings on the receiver combined with the stock show it was a bit more organized than that. Soldiers will sometimes carve stocks, but to imprint metal requires some stamps and a hammer, and these stamps aren't a average European stamp. Here is the link to the exact picture with the stampings on the receiver (on the left hand side, close to the stock on the receiver itself).
http://www.collectorssource.com/med...3525d08d6e5fb8d27136e95/s/t/steyr_nr46264.jpg
It would help if they had better photos but with the evidence available I am now fairly confident it is a Siamese rifle, or at the very least it has something going on with it beyond your average M88/90 rifle. Another thing with this particular rifle is the middle barrel band is on backwards, as the volley sight post should be on the right.
I am not really trying to be argumentative, just expand my knowledge on these odd rifles. Unfortunately information on Mannlicher rifle systems is very limited which means most that I learn is through hearsay or though knowledgeable individuals (I own the only book I know of, and it is a pretty poor book as far as they go, there is tons of information that could be added to it such as Bulgarian rifles and Siamese ones).