Have owned a venezulean navy fn 49 for for several years and have shot it with a lot of 175 gr ammo, but was wondering about using some lighter bullets, but want ultimate reliability- something the rifle has always exhibited with the heavier bullets. Need advice on gas regulation adjustment and although I can do the math on ballistic performance for the lighter bullets, front sight past adjustment advice would be helpful. BTW~ buy one of these if you ever get the chance-old school cool and milled out of billet. Had to add that the rifle is chambered in 7mm mauser (7x57)