Picked up a piece of what I thought was 45 brass at the range. Checked the head stamp and it had FLB 11.25x23 on it. I have never seen that number before so i googled it and yes it is 45 brass. According to google it is Argentianian -abrica Militar "Frey Luis Biltran", San Lorenzo, Argentina. It is also Berdan primed. I thought it was kinda cool !