Below are a few comparison shots of original bcd rifle bolts. The bolts on late bcd rifles will be serial numbered with the last 4 digits on the root, gas shield, and last 2 digits on the safety, cocking piece, and firing pin (these rules apply to late bcd rifles only, the earlier guns had 4 digits on cocking piece and safety). I tried to illustrate what the proper font should be with these pictures. The best thing about late bcd's is the finish- it's nearly impossible to restamp a bolt and match the phosphate finish on them. Pay close attention to the root, as circular mill marks are common.
Next I am going to touch on the subject of fake long side rail rifles. Only because I was able to purchase one for a reasonable price, I bougth one and studied it's construction. I thought it impossible to recreate the thick reciever on these- wrong answer. With some skill with a welder, and a good machine shop, it's not that difficult. On this one, an original bolt was matched to a serial restamped barrel! The bolt is not always the renumberd part, and it took some study to figure it out. The bcd firing proof is an odd looking one, having clipped wings. The firing proof was changed at the end to the full eagle style-- more on that later. Here are some pics of the original bolt, and the renumberd barrel. Notice the black spots under the serial on the barrel- this is where the old serial and firing proof was welded up and smoothed over. Without taking the gun apart, it would have been hard to tell the barrel was not right. Also, notice the firing proof:
Like I said before, the firing proof on late bcd rifles is distinct. Quickly (as to not bore anyone any further)- the early style proof was used up through the 99,999 serials, and rolled over into the next serial range, up to about 5000. From about 5000 on, the new style proof was used. Below are the 2 types of late bcd proofs. Mainly, after the MG barrel guns were produced, the new style proof seems to show up. This range is not set in stone, just from examples studied.
Last, I will touch on configuration. bcd marked rifles will have standard configuration stocks up until the 75000-85000 range. The overlap is considerable though. One thing that remains constant, bcd guns will be marked with a small Eagle large H on the butt, along with a C proof at the keel of the stock. Wood types are either regular laminate or odd size laminate, with the odd size laminate stocks being more rare. The takdown disc dissappears at about that range, replaced by a hole in the buttplate. The stocks also start to show corncobbing around the recoil lug, or roughness. The bayonet mount and cleaning rod provision were used until the end of production. Some of the last bcd rifles (16000 range) will lack the Eagle H proof, and will not have the 749 acceptance proof on top of the reciever. Below are wood types: