I would keep to a factory round if I had any dreams of travelling internationally with a rifle. My experiences in Africa and Russia made me glad I was carrying famous rounds. My barrels were inspected for calibre stampings. The head stamps on the cartridges were checked, as were the ammunition boxes for calibre designation. Other folks say it hasn't happened to them and bless them. Allocate 6 hours to get through Russian customs with everything above board with an experienced interpreter. If you have a custom I don't know what would happen. Just my .02$ worth.