Rafter:
I don't know the answer to your specific question,but...
The 40-X was made in several different configurations and used two different actions. Total production was approximately 29,000. That number does not include the limited production of the International Free Rifles and "Sporters" which, I believe still available from the custom shop.
Let me know the model you have (40X-S1, 40X-H1, etc) or give me a more detailed description of the gun and I may be able to give you more information.
John Gyde
40X .22 rimfire
M/40X IFR
Yours sounds like an International Free Rifle. They were made from 1960-1973. A total of only 123 were made. The 1/2 oz trigger was an extra cost option with the gun's retail at $478.00 vrs $361.05 if equipped with the standard 2 oz trigger. Very few (exact number unknown) were equipped with the 1/2 oz trigger. From your description, yours was made in the early 60s.
John Gyde
John Gyde