I have recently redesigned an antique falling block single rifle action and need some help calculating the poundage of the firing pin spring. A test that is often used to determine if a firing spring in a gun is still in serviceable condition is to place a coin, which weighs approx 10 grams on the breech face of a gun and fire it. If the firing pin has enough striking force to propell the coin approx 1.5m vertically into the air all is deemed well. The prototype action currently uses a spring and firing pin to the following specifications spring details; o.al. - 24mm, installed length - 20.5mm, compressed length 14mm, no of turns- 6.75, wire dia 2.00mm, external diameter 13.7mm, rated at 108"/lbs. (11.298482902 newton meters) firing pin weight 28 grams, which is approx 1 oz (16 oz to the pound) firing pin travel from cocked position = 6.5mm height of 10 gram coin reached when placed on breech face and fired = 2.9m, which is obviously almost double required height. If the firing pin remains the same weight, what reduction of the spring poundage will be required to propell the 10 gram coin only 1.5 meters vertically? Can anybody advise me?? Thanks in advance.