Louis

The circled "T" mark on your rifle is Austrian and is an abbreviated form of the word Tiegelgussstahl. According to my source, his denoted the use of a new high grade steel. This mark is thought to have been first used either towards the end of or just after World War 1. However, because MS rifles weren't manufactured during the war and possibly not until about 1920, your rifle couldn't have been manufactured before that date - not if it has a circled T mark. So in your case the starting point is circa 1920. And, as you know, rifles exported to the UK had to be marked "Not English made" from 1925. So, your rifle was probably made between 1920 and 1925.