Bulgarian Battalion size

I ordered the Micromark army lists covering the Balkan wars the other day and they arrived this morning. Good fast service and quite interesting products. My only concern is that the Bulgarian Infantry division list covers 1912 to 1918 which was quite a period of change in the Balkans. It also shows an infantry battalion being made of 4 companies of 263 men. I had always believed that the Bulgarian battalion was originally made up of 6 companies. Which is why they were quite hard hitting certainly in the First Balkan war. I need to find out when the change took place as the size of the battalion is obviously going to have a big impact on my games and my wallet.