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If that action has 'Mannlicher Schonauer 1930 System' stamped on the left receiver rail it is (was) a military Mannlicher Schoenauer 6.5x54mm, more specifically a 'Greek Contract' Model 1903 / 1914 / 1930.

It's likely a sporterized surplus rifle, thus the homemade sights.

Here's a link to some 'Greek' MS. Scroll to the last for the 1903/14/30: 1903/14/30

Here's a video where Othias will tell you all about it and Mae will demonstrate. It's over an hour long and very well worth the watch, as are his other videos. He gets to the 1903/14/30 at 48:15, describes popularity of 'sporterized' Greek MS at 51:50. YouTube:

From a Wikiwand artticle:
The Mannlicher–Schönauer rifle was the main small arm for the Greek military for some of the most active years of its modern history. Greece was almost continuously in state of war between the years 1904–1922 and 1940–1948. The version history of this rifle is rather confusing. It appears that the Greeks issued four main contracts. The original Steyr-made Y1903 ("Y" stands for model in Greek), started being supplied in 1906–07 to a total of about 130,000 long rifles and carbines. This was the main weapon during the victorious Balkan Wars of 1912–13

The Greeks seemed satisfied with the rifle's performance and their armoury was increased with a new batch of 50,000 rifles from Steyr in 1914, with the model Y1903/14, presenting minor improvements, most obviously the addition of a full handguard. These rifles were used for the first time in World War I. When the war broke out, the Austrians stopped the delivery of the rifles, as Greece chose to be neutral for the first three years.

Following the Asia Minor Campaign (1919–22), the Greeks were in urgent need of serviceable weapons and tried to get Mannlicher–Schönauer rifles from every possible source in order to replace war losses (almost 50% were captured by the Turks). Starting in 1927, Greece received about 105,000 "Breda" marked Y1903/14/27 rifles. This Italian factory might have used Austrian captured parts and machinery, or more likely, might have just mediated on behalf of the Steyr factory, due to treaty restrictions with the Austrian weapons manufacturer. These rifles saw extensive use against the Italians and Germans in World War II and many passed to the resistance fighters and thence to the combatants of the Greek Civil War that followed. The last official contract was in 1930, when they received 25,000 more Y1903/14/30 carbines, this time directly from the Steyr factory.