1945
Best left to a factory trained gunsmith.
On the top of the tang.
1952 was the first year that FN made Brownings with the cross bolt safety as standard. I have seen a few guns made in 51 with the cross bolt and I have seen at least one 1952 gun with a front trigger safety. Many of the older guns were converted by Browning to switch the front trigger safety to crossbolt. You can tell this if there is a slot in the front of the trigger guard. If the customer paid, he could have a new trigger guard installed along with the conversion, thus it is not possible to date a gun by the safety alone. FN continued the front trigger on their guns that they sold worldwide until the early 60's. These were not Browning Arms Co. guns
You need the services of a Browning trained gunsmith
Requires in person examination.
This weapon will need to be appraised and compared against known samples.
You will have to call Browning to see if it is even possible.
Your shotgun will bring between 350-550 dollars,depending on overall condition and a good bore.
Please help us out. The "SR" does not compute. What guage is it?
If you have enough money, yes.
No one Mossberg shotgun. Tell us what you have, we may be able to answer.
You must clearly describe what "up front safety" means to do.