It seems like opinions / experience on this is all over the map. While most seem to be in the 10, 11, or 12 lb Recoil spring area some like the 9 # and some go even heavier to 13 lb.
I decided to ask the question to Ed Brown and Wilson
Ed Brown : Our recommendation for standard pressure ammo is 10 lbs, so if you're shooting a hotter load, suggest going with a heavier spring. We also suggest contacting Springfield regarding their recommendation for +P in their firearms.
Wilson: For plus P 9mm I would go with a 13LB and a 12LB for standard ammunition.
For Springfield Armory. I called them as I wanted to ask about + P as suggested by Ed Brown
The official stance is: Any standard 9mm ammunition is OK. NATO or + P 9mm ammo is OK in a full size (5") 1911 but they don't recommend a steady diet as you could get more wear over time. They won't recommend +P+ as there is no SAAMI standard. Non +P 124 gr, even the 1181 fps or the Norma 1181 FMJ (Hungarian or Swiss?) and 1200 fps TMJ (US assembled) loads are fine. ( Norma told me that the thinner jacket on the TMJ loading as mostly where the extra speed to get 1200 come from)
As far as springs; SA assembles them with a 9 lb spring to cover the spectrum of standard ammo from lighter 115 grain loads to the standard heavier bullet loads. and occasional +P. They said if I was using the 1181 - 1200 FPS 124 gr ball ammo and the Speer 124 Gr +P gold dots it wouldn't hurt anything to bump it up a pound or two. I went ahead and removed the 12 lb spring and put an 11 lb in as kind of a middle ground. Now I'll see where the ejected cases land and how it shoots ( muzzle dip etc ). For my Ronin and the factory loads used I don't think I would want to go heavier than a 12 lb action spring and I think the 11 lb may good. Time will tell.
I probably think too much but I am by nature curious and want to learn all the time. This is actually the first 9mm of any make that I have ever owned. My previous 1911 was a .45 Cot Series 70 and back then 40 years ago I just shot the heck out of it and knew little about spring rates etc. I also like to tinker now that I have retired.
