You must identify the model number of the gun - the serial number is not sufficient.
No.The rifle grenade firing adapter was made for the M-1 Garand rifle only.
m=bar 7=1967
In the year 1880.It was the model 1878 single shot rifle.
$200
100-500
100 USD
your rifle was made in 1940
On of the weapons in the Vietnam war were the M-16A1, 5.56mm Assault Rifle and the CAR-15, 5.56mm Assault Rifle also these M-60, 7.62mm GPMG, BROWNING .50 Cal Machine Gun, BROWNING .30 Cal Machine Gun, M-72, 66mm Light Anti-tank Weapon (LAW) and many more!
What condition is it in. That determines the value.
100-450 or so
100-5000 USD depending on specifics.
Maybe around $1,000 $2,500 the most.