This bayonet has a distinct short roundish brass hilt that is just a little different then Ames' hilt type #1.  The smooth ribbed brass hilt is 118 mm long and has 16 ribs.  The muzzle ring is flush to the hilt flat and the inside diameter is 20.9 mm.   There is a forward swept round finial on the bottom of the guard and no finial on top of the muzzle ring.  The press stud spring length is 48 mm. There is no steel rivet in the center of the cross guard.  

The lug slot is chamfered around the top edge and there is no guide slot.  The hilt flat typically has a 4 to 5 digit serial number stamped vertically between the muzzle ring and lug slot in a 3 mm font.  

In the following two pictures the 48 mm long Merrill press stud spring is on the top.  The 51 mm long Collins spring is in the middle and the 41 mm long Ames spring is on the bottom.  It can be seen that the Merrill spring is much thicker in width than the Collins spring and lacks the tooling to thin the spring beyond the screw hole as found on the Ames spring.  Just different in every aspect.   

In the following picture the Merrill press stud spring screw is on the top.  The Collins screw is in the middle and the Ames screw is on the bottom.  It was originally believed that the Merrill screw was a replacement but multiple examples have now been observed with the same screw.  The Merrill screw is very noticeable because it does not quite sit flush to the spring.  You can see this in the above picture of the hilt flat.

In the following picture it can be seen that the Merrill press stud (top) is made in the same manner as the Collins press stud (middle).  The Ames press stud (bottom) is distinctly different.