EDGE 15lb mainspring & ?

[seanr]

OK in the pursuit of the customers desired "fastest/flattest" gun cycling we took a 38 super (minor STD/Limited Gun) EDGE tricked the trigger with Cylinder and Slide components - the hammer is light, then fitted a 11lb recoil spring and a 15lb mainspring (both ISMI)

Recoil (flatness) and Recovery (sights returning to desired location for 2nd shot) were AMAZING very flat, very fast - a joy to shoot...

the cloud in the silver lining was light strikes (lots of them) - Tried using (crush primed) Federal small pistol to no real avail still getting about 4 in 10 clickers, in the end just to get the thing to function test we cut about 10 coils of the firing pin spring. Works but seems like a short fix and we don’t want any run aways here!!!

The hammer fall is frankly pissweak with the 15lb and it’s no surprise we are seeing the light strikes...all the guns I do normally have 17lb mainspring as a minimum, but we are chasing the unicorn here...

Any suggestions to what we can try to get more ignition reliability without removing 1/2" of the firing pin spring?

[SLM]

If you haven't, try an extended firing pin. I have 15 pound mains in both my 9mm Open guns with M2i (Matt McLearn) firing pins and haven't had any problems with Winchester small pistol, small rifle, CCI small pistol, brass colored Wolff small pistol or Fiocchi lead free small pistol primers.

[BMartens]

If the extended firing pin doesn't do it I believe the Unicorn will suggest the 17lb mainspring. I tried a 15lb mainspring in my single stack and went back to the 17lb before I finished the second magazine...

[G-ManBart]

Yeah, extended firing pin and even that probably isn't enough to fix the problem. 17lbs is about the limit and I know a couple of famous gunsmiths that really only like to use 19lb springs.

Putting a radius on bottom of the firing pin stop can really help reduce the amount of effort it takes to start the slide moving back, and that will cut down on muzzle flip somewhat. R,

[twodownzero]

Funny thing is, my most recent email from STI states that a 15 lb. spring is stock on all guns that use small pistol primers (9mm, .38 Super, .40, etc.).

I suspect that they lie. I run a 17 lb. in mine.

[Raudi]

I guess it has to do with the ISMI poundage. In my experience ISMI springs with the same nominal poundage tend to be a tad lighter than Wolf springs with the same nominal poundage. (Had a 12.5 lbs recoil spring from ISMI that was lighter than a 12 lbs from Wolf.) Anyway, I run my 40 with a 15 lbs Wolf mainspring and had 1 light strike in about 10000 rounds. It very probably was due to a high primer, but I switched to the Mclearn firing pin, just to have some extra leeway. Since then no light primer strikes at all. Primers I use are CCI, so you should be on the safe side with Federal primers. (Trigger components I run are cylinder and slide sear and disconnector and a Doug Koenig hammer, in case it makes any difference.)

[ebg3]

An ext. pin should solve your light strike problem. Also, try an 8 or 9lb recoil spring.

[G-ManBart]

I guess it has to do with the ISMI poundage. In my experience ISMI springs with the same nominal poundage tend to be a tad lighter than Wolf springs with the same nominal poundage. (Had a 12.5 lbs recoil spring from ISMI that was lighter than a 12 lbs from Wolf.)

I'm not so sure that's really a pattern as much as poor QC or an inexact process. I built a spring tester and checked new ISMI and Wolf springs and found that almost none of them were what they were rated, and both had springs both heavier and lighter than rated. That was when I decided to switch to Sprinco springs (not the recoil reducer) which seem to have a much higher level of QC done to them. R,

[el pres]

?? I have an Edge in .40 with 30k of mostly CCI's and about 4k Wolf primers through it.

15 lbs. main spring with not "one" misfire ?? I just put in a 15 lbs mainspring in my Spartan and I'm at about 3k with no misfires ?? Everything else is stock, pins, hammers, etc.. I'm useing STI packaged springs.

[Raudi]

I guess it has to do with the ISMI poundage. In my experience ISMI springs with the same nominal poundage tend to be a tad lighter than Wolf springs with the same nominal poundage. (Had a 12.5 lbs recoil spring from ISMI that was lighter than a 12 lbs from Wolf.)

I'm not so sure that's really a pattern as much as poor QC or an inexact process. I built a spring tester and checked new ISMI and Wolf springs and found that almost none of them were what they were rated, and both had springs both heavier and lighter than rated. That was when I decided to switch to Sprinco springs (not the recoil reducer) which seem to have a much higher level of QC done to them. R,

G-Man Bart,

That is very probably true. My sample was certainly not big enough to draw any definite conclusions. What I stated was just the pattern I observed with my limited batch.

[ParaGunner]

I agree with Gman,Sprinco recoil springs are great. I switched to them and haven't looked back.

[seanr]

I too had seen the famous "15lb main spring in STI as standard", but from memory it was on a forum and not on anything official...please feel free to correct me if i am wrong.

One thing i CAN say without question - the mainspring that I remove from the Edges, Trojans and Rangemasters i have worked on is significantly heavier than the 15lb (or even the 17lb ISMI springs). Maybe these are put in by the local agent - its a moot point, the felt recoil and hammer fall is reduced using the ISMI product...

We are getting a Mclaren Extended Firing Pin for the "unicorn" and we will see what happens.

thanks for the input the suggestions are a nice way to confimr the ideas we had locally!

[kgunz11]

It's true, STI uses what they rate as a 15 lb mainspring. I have not tested it to confirm that it is actually 15 lbs. I trust them to know what parts they are using in their guns. I also think installing a 17 lb ISMI might make the gun appear to shoot a little flatter as it will slightly retard the energy in which the slide slams rearward aiding the recoil spring in doing its job. It will also allow you to use a slightly lighter recoil spring to in turn drive the slide back forward. Grabbing the next round with the breech face, stripping it from the mag and up the feed ramp into the chamber will retard some energy of the slide going forward and prevent the muzzle from dipping. There is a bit of a relationship there.

[TonyH]

I have used 15# springs for several years now in many different guns with no problems. Winchester primers!!!

[seanr]

I guess it has to do with the ISMI poundage. In my experience ISMI springs with the same nominal poundage tend to be a tad lighter than Wolf springs with the same nominal poundage. (Had a 12.5 lbs recoil spring from ISMI that was lighter than a 12 lbs from Wolf.) Anyway, I run my 40 with a 15 lbs Wolf mainspring and had 1 light strike in about 10000 rounds. It very probably was due to a high primer, but I switched to the Mclearn firing pin, just to have some extra leeway. Since then no light primer strikes at all. Primers I use are CCI, so you should be on the safe side with Federal primers. (Trigger components I run are cylinder and slide sear and disconnector and a Doug Koenig hammer, in case it makes any difference.)

?? I have an Edge in .40 with 30k of mostly CCI's and about 4k Wolf primers through it.

15 lbs. main spring with not "one" misfire ?? I just put in a 15 lbs mainspring in my Spartan and I'm at about 3k with no misfires ?? Everything else is stock, pins, hammers, etc.. I'm useing STI packaged springs.

I have used 15# springs for several years now in many different guns with no problems. Winchester primers!!!

some facts:

The unicorn is running a 15lb "ISMI" main and 11lb "ISMI" recoil spring - I know as I opened the packs for them.

The rounds are using crush primed Federal Small Pistol...these go off in custom ICORE revolvers with LIGHT triggers no problem.

The stock mainspring spring in the unicorn was heavier (much heavier), than the 15lb ISMI that replaced it.

We have a Mclaren Extended firing pin on order from the states...but have yet to test (takes awhile to get to Oz)

We want to run the ISMI combination because that was what gave the really nice results (sans the light strikes).

To ask a modified version of the orignal question...

(apart from the extended firing pin issue) does anyone have experiance with a functioning, no light strike EDGE with ISMI 15 Main/11 Recoil?

We are also getting in a Koenig hammer as well - customer is happy to spend some coin on the chasing of the unicorn (and there is nothing wrong with me bodding the slightly used C&S ultralight hammer for the parts bin!)

Thanks in advance!

[Bear23]

I use a 15# mainspring with lightened hammers, i.e. Koenigs. Ti mainspring cap and strut. I generally use an ISMI 17# in most triggers.

I also heavily polish the firing pin channel with 400 grit and take the firing and polish on a wheel.

I've found in my SV built guns, 15#'s are not a problem due to the light trigger components.

RM

[seanr]

Unicorn captured

We ended up using the following combination:

ISMI 15lb mainspring

Cylinder & Slide Ultralight hammer and sear (the Koening gave a lighter but "mushier" hammer fall, so we ditched it!)

ISMI 11lb recoil spring with 1 x Wilson Shok Buff on a Tungsten FLGR

McClaren Extended firing pin with ISMI firing pin spring.

No more light strikes (was the firing pin that did it), one awesome shooting EDGE and one happy customer

thanks for the input

[twodownzero]

I too had seen the famous "15lb main spring in STI as standard", but from memory it was on a forum and not on anything official...please feel free to correct me if i am wrong.

I have an email from David Cupp at STI that confirms this. 15 pounds in the small pistol primer calibers and 19 pounds in everything else.

I use a 17 lb ISMI in my limited gun (.40 STI Eagle) and 19 lb in my Single Stack (.45 Kimber).

[G-ManBart]

I'm not buying STI's claim it's a 15lb spring. I have one out of my Trojan that was replaced as soon as I got the gun and set it to Matt M. for his magic. I also have one that was used a bit out of an Edge. I'll compare against a new ISMI 19lb spring and see.

People need to realize that the weight listed on the side of a spring package (at least from Wolff and ISMI) is only a ballpark and they're frequently off by a fair amount. R,

[twodownzero]

I actually agree with you. The spring I took out seemed heavier than the one I installed.

[seanr]

no doubt...the "stock" STI springs were much heavier than the ISMI 15lb springs. I do not have empirical data (I havent tested them other that using the Mk1 eyeball and my fingers) but after several years as a mechanical engineer and a toolmaker, I know the weight of the STI is heaver than 15lb/or the ISMI 15lb is lighter than the STI...moot point in many respects.

We decided to stick with the ISMI in the unicorn simply because we had a "known result"...we knew what springs were in the gun and we knew that while it shot really well, the light strikes were a killer.

The extended firing pin solved the issue, no doubt the effect of the given kinetic energy was multiplied by the "deeper" strike of the extended pin.

Gun works, customer happy...problems solved (till he needs new springs )

Thanks for the input guys!