First off, welcome to the forum! As to your bayonet, it is hard to say when the knuckle bow was added. I would say that it was done in the last 50-60 years though and here is why: What you have is a model 1892 Krag bayonet, they were pretty much out of front line service by WWI. It is paired up with a picket pin scabbard which was out of service soon there after. Bannermans acquired both items in surplus from the US government in the 30's or 40's, I believe. You then have a mail order military surplus company with bayonets without scabbards and picket pin scabbards without picket pins. Soon there after the legend of the cavalry Krag was born. These were sold by them in through the late 50's, if I remember correctly.
Thanks Jim! I replied when you answered this question, but it looks like my response is not showing? I appreciate your answering so quickly and your wealth of knowledge!