I have a full size - had 2 failure to load problems at around 1,500 rounds- the slide was not closing - had to bump it for the last 1/2 inch - I called and ordered 3 recoil rod/springs.
They were on back order for a few months - I finally called and got them to ship me one.
I tested both new and old springs - old spring tested 14.5 pounds - new spring was 16 pounds.
I have not had any issues since replacement. I plan to test the strength every 500 or so rounds - just to see if it changes. I do not know if the original spring was weak to start with - or wore out quickly. A new one is $7.00 -
I made my own spring weight test machine - it is very crude - but works - I need a better scale.
I took an piece of 2x2 that was left over from a project about 12 inches long (a 4x4 would also work)
Took a drill bit that was slightly larger that the end of the recoil rod and drilled a hole all the way through the 2x2.
Next took a drill bit slightly larger that the diameter of the recoil spring and drilled it about 3/4 the way through the 2x2 in the same place as the first hole.
Then I took a scale (I used our bathroom scale)
Put another scrap piece of wood on it - and set the scale to zero
Then stuck the recoil rod into the hole I drilled - and pressed it against the wood on the scale - using the board with the hole drilled to force the spring to compress.
I must have too much time on my hands.