Just a little info...all (most) premium barrel manufacturers stamp the end of their barrel blanks with their brand, caliber, bore size, twist rate, material used, and sometimes even a production serial number. Other larger mass production manufacturers often do not due to volume and time constraints. If you are ordering a barrel from whatever company you choose to finish the blank, always request or demand that you get that coin for a few specific reasons. First reason is that if there is any problem with the bore in production (and yes, it happens to the best of them), the first thing they will do is ask for this information, so it's a good idea to keep this coin handy until you have determined that all is well. Secondly, it's a surefire way of making sure that you have gotten exactly as you paid for and will ensure you have a record for future purchases. Lastly, if you are an avid shooter and go through a lot of barrels, these are nice to have around. I know that @padom has a ton of these and has already or is in the process of making a table top under a thick coating of urethane out of his collection.
John
John