Being prior military, I have worked on many rifles due to low standards of up keep because of untrained military personnel. I have found that observing a rifle in action speaks like a professor in college. I bought a Marlin 39AS from a auction. I like 22's so this was going to be my new weapon of mass destruction against those Tree Rats. Well, I took it home went to Wal-Mart bought a BSA Scope and a Weaver Mount. When i got home i then proceeded to make this scope a forever part of my rifle. Well, I then took it to sight in the scope and found this rifle Misfires. I figured it was the 22 rounds i was firing so i went and bought new rounds once again it Misfired. Well i figured it needed cleaned SO, I then took it down and cleaned it. After assembly i took it back out since it was seemly dry firing ok. I then loaded the chamber again and prepared to shoot. The hammer dropped but it did not fire. After several rounds i thought well something broken. I then mailed this rifle back to MArlin for repairs. Marlin, replaced the firing pin which is a free floating firing pin. I then recieved it back and replaced the scope mount and scope back on and then took it to be fired. I was assured this rifle fired fine. Once again it Misfired. The firing pin was hitting the shell making a light indent in the rim but it wasn't firing unless i pulled the hammer back a second time and fired it. I then was sure i knew what it was! The Hammer spring! So, I took it home and pulled the hammer spring out. The spring had been grinded on so i enlongated it a little reaplce it and the next day took it out again to test fire it. Again, It misfired after firing the first shot off fine. Well, I remember looking in the chamber and seeing the front of the bolt. I seen that the round portion which the shell sit into once the bolt is locked in place was not like normal rifle It sat were the round portion barley toughed the top of the bolt. I then brought it back home. After oberserving it a few minutes i pulled off the scope and mount. I then pulled the lever out causing the bolt to move outward. I then measured the scope bolt thickness as compared to the thickness between the top to the rifle. The bolt had plenty room and did not sit down on the bolt. I then remember that i saw the bolt front resting upwards so, I then closed the bolt back and took a tooth pick and measured the distance between the front scope mount screw hole on top and the bolt inside. I then compared the screw with the tooth pick and found that the front scope mount screw was to long and was barley touching the firing pin causing it to slow down and not impact the rim of the shell to make it fire. To comfirm my suspicion i took the rifle back out and it shot fine with the scope mount off. Be advised if you place a scope on your MArlin 39AS .22 rifle and misfires, You need to take and get shorter screws. they should only be the length of the filler hole screws. I have found many problems and concerns with this misfiring after a scope had been mounted on the Marlin 39AS Golden .22. The scope mount screws are the problem! Hope I helped you get into a better mood after a hard day of misfiring problems!