Impossible to answer since you did not mention the make and model.
Very Good Gun. Built in 1954 thus over 50 years old and fine weapon as WAS built years ago. Retail now days is $150 to $200.
Your gun is 36 years old built in 1972
1592
dugh
If there is not an adjustment built directly built into the gun, then it would be illegal to do so in the United States.
Contact a manufacturer, or custom gunsmith.
Probably the Chinese.
None
It was made in 1967
Post the serial number of the gun and I'll let you know.
Eli Whitney built the prototype gun locks in 1801
your gun was built in 1910