Bayonet lug top or bottom?

[RSMorris]

What is the advantage of having the bayonet lug on the bottom v. the top of the barrel? I read a bottom lug bayonet had a different slot in the socket than a upper bayonet lug socket. The M1842's of both armories had the lug on the bottom but the Springfield M1861 had it on top. What up wit dat?

 

[Conquerordie]

Well the 1842 has a front sight brazed the the front barrel band, so the lug is on the bottom. The M1861 has the front sight on the barrel, so it can be used as the lug for the bayonet as well.

 

[RSMorris]

Well the 1842 has a front sight brazed the the front barrel band, so the lug is on the bottom. The M1861 has the front sight on the barrel, so it can be used as the lug for the bayonet as well.

I am just wondering what is the advantage over one or the other and if in fact the bayonet sockets are different. I have 10 muskets that are a mixture of upper and lower bayonet lugs.