Hammer spring? Hammer wear?

[Joseph Scott 0]

I received one of the trigger groups which had double fired. Noted top of hammer worn more than normal and hammer tension was harder than normal. Someone installed a 1/4" longer spring for more tension. When I pulled out spare springs marked with correct number, they are shorter and heavier wire so that they don't want to slide on hammer strut. Several used springs measure 1-7/8" x .050" wire and spring moves freely on strut. New(?) spares are 1-5/8" x .060" wire. The (new) spares came from Numrich many years ago. Does anyone know if the LMG had a different hammer spring? If so, I suspect that they might have been mixed up as they look similar. If you have a spare hammer spring, please measure them and let me know. I am wondering if the excess hammer tension may have effected sear engagement or the hammer face wear may have prevented bolt from pushing hammer down enough to catch both sears. I hope these technical discussions don't bore everyone and are helpful.

[TomW 0]

Joseph

I do not find these techinical exchange's at all boring, but very helpful. After Jim Pullen started this website, & people started to pull the Johnson 1941 Rifle out from the back of the closet, problems & questions started cropping up. It was only through the help of the many contributing experts, and the publishing of the Johnson Rifles and Machine Guns Book, that they have been answered.

When ever I use to order parts from John Darling, I would have about 20 questions ready to ask him. To his credit he was always willing to answer every one of them.

I checked my parts warehouse & found that I have #5 of the suspect Numrich hammer springs, that I purchased back in early 2002 for $3.15 ea.. You did not mention it, but they appear to only have 11 links of twist in the spring, but otherwise, mine are the same as yours. Also tightish on the hammer strut.

I paid $3.05 for hammer springs in 2001, and I think they were still correct at that time. The one that I have left is 0.050" wire, but is 2 inches long with 13 links of twist. The new price today, for hammer springs?, is $3.35.

Sometime I must check out one of the Johnson's that I rebuilt, (have not fired yet) to see which hammer spring was used.

[Joseph Scott 0]

Tom, my shorter springs have 11 turns vs 13 for the longer. I found a LMG hammer link in my future project stuff and the short spring will slide nicely on it. I also noted that Gun Parts has a different number for the LMG spring. Their numbers are same except for the suffix "a" or "b". We may have mixed up springs from long ago. Maybe we can find a drawing or specification for the springs. Springs are usually specified by ID or OD, wire diameter and free length. Maybe Jim can find out if there was a design change during production. Also think we should check the hammer link shaft for smoothness (no wear or burrs).