Recoil spring by power factor

[Intercooler]

  I have been looking at Henning's site which lists springs:

http://www.henningshootsguns.com/shop/pinspringscrew.html

It appears a 20PF increase equals 2lbs of spring increase. Some of the hottest 10mm is 240PF.  Does this mean a 20lb spring may do more harm in cycling?

[The_Shadow]

You will have to play around some I suppose, the slide mass of the EAA is probably heavier than that of the 1006's.
The 1006 used a factory spring of 18 lb and I settled on 22 lb for most all of my stuff to include the 10mm, 40S&W and 9x25's,
As I stated before the I felt the 24 lb was too much spring for everyday stuff, but some of those loads from Underwood, SwampFox and even the matching loads using the 200 gr Speer Gold Dots may benefit using the 24 lb.  Some of these have shown the case to pull free from the extractor during recoil/extraction phase, leaving the case inside the chamber or loosely laying in the ejection port.   That is why I had mentioned about dropping the load down on the 200 gr Speer Gold Dots, to allow better timing without having to do a spring change.

[Intercooler]

The lightest I have is the 11lb which looking at Henning's page is Major in 9mm (Underwood's 115 +P+).  Those other 9mm rounds which are weaker may not eject properly until I go down to a 6. I'm going back today with the 11 and will report back.  With some of the smashed up brass I have seen on here I'm wondering if pistols are being oversprung.

[The_Shadow]

In the case of too high of an impulse vs. certain springs in use.
The cases that get smashed between the ejection port and barrel could be that the impulse of the cartridge is pressing outward and holding tight to the chamber still as ejection starts, being pulled free of the extractor, then smashed by the returning slide to battery.

Then in some instances the recoil spring may be bunching up (too long or to large in diameter or round wire vs. flat wound springs) adding drag or not allowing the extracted brass to fully strike the ejector with enough force to kick it out of the ejection port or out from under the extractor. These can also be smashed into the barrel by the returning slide.

In the case of too light of an impulse vs. certain springs in use.
Extraction may not occur for lack of impulse vs. to heavy slide mass & recoil spring, case may remain inside the chamber.  By going to lighter spring may help in some instances, If the slide mass and frictional forces are too great the lighter spring may not help.  If the lighter springs do not help, more impulse will be needed to get the mass moving to have extraction & ejection occur.

It goes back to working inside a required amount of energy to do the job or adding or subtracting spring to compensate for the energy being used.  Delicate balance especially if a broad range of ammo impulse id being used!

[Intercooler]

    Remington had a few malfunctions with the 11lb spring but the PPU being hotter functioned pretty well with it. Not perfect but 85% of the 150 or so rounds I put through it. Given the PF of a 115gr in this Long Slide with a flat bottom I'm going to order a 6lb and 8lb. Hopefully those will work for even the weaker 9mm rounds. 

[RkyMtn]

It goes back to working inside a required amount of energy to do the job or adding or subtracting spring to compensate for the energy being used.  Delicate balance especially if a broad range of ammo impulse id being used!

I had a long conversation with my Bob Marvel trained gunsmith and I was amazed at how finicky some guns can be while other will digest just about anything you stuff into their chamber.  My gunsmith was working on an officer model 1911 and he put every kind of spring in it to try and get it to cycle properly, cutting small parts of springs off,....  Finally he modified the recoil system to use a Glock flat coil spring.  Bob Marvel incorporated it into his signature gun that Nighthawk Custom makes.

It really makes sense as to why the military has strict specs on their ammo.

Thank goodness most of my guns have been real cooperative!

[The_Shadow]

In this instance Intercooler is using the EAA chambered in 9mm, there are many different levels in ammo and his gun has a heavy slide that takes some energy to get things cycling.  This gun is also new so it may also require a little amount of shooting to loosen things up.  I think he's looking for what will provide reliability across a spectrum of impulse levels for best function from mouse farts to master blasters.  I believe he wants to also run a conversion to 10mm for this setup.  He has shot a ton of mild to wild 10mm ammo form some of his guns and has a good spreadsheet of velocity performance.

Not all guns utilize the recoil spring weight the same way, 1911's with the swing link help to maintain lock up, where as S&W, Glocks and other makes utilize specific angles and the recoil spring to hold the dwell of lock timing.