muzzles of the rifle barrels appear to be octagonal (?) bores....four large lands and grooves (similar to enfield/snider?) on the first three tubes....and the fourth barrel has six quite small lands with much broader grooves.

guess they ran out of matching blanks for this bizarre exercise...thanks for letting us look mike.

best regards,

tom

"it's a poor sort of memory that only works backwards."
lewis carroll, Alice in Wonderland