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Extended firing pin for SVI


HDGoose

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What are other SVI shooters using for extended firing pin? I've had some light strike problems lately so I ordered a Dawson which is .035" longer than the stock SVI FP but had to trim 5 coils from the FP spring just to be able to get the FP stop in place. I assume this is because of the IBF?

 

Does someone make an extended pin that doesn't require trimming the spring?

 

 

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Taking the IBF design into account, I don't think there are firing pins out there you don't have to trim the firing pin spring. 

 

The svi firing pin is similar in design to the Dawson pin, right?

Edited by yoshidaex
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Just my humble opinion but if you have an unaltered SV pistol that is having light strikes I would look everywhere else before I changed out parts. Type and brand of primers, seating depth, etc. 

 

i have put many hundreds of thousands of rounds through SV pistols and can honestly say the pistol was never responsible for light strikes. Adjustments that moved on my loaders were the biggest issues ( high primers) followed by certain brands of primers. 

 

Again, just my opinion.  And my experience. ?

 

 

 

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I have had great luck with uncut  Wolfe extra power FP springs and stock SV firing pins in all 3 of my infinity pistols.

 

As Don_B said, primer seating depth and brand could play at part in this.

 

Whats the round count on the gun? Have you ever changed the main spring?

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11 hours ago, yoshidaex said:

Taking the IBF design into account, I don't think there are firing pins out there you don't have to trim the firing pin spring. 

 

The svi firing pin is similar in design to the Dawson pin, right?

Yeah, the SVI and Dawson are similar but the SVI is .035 shorter and the shoulder that the FP spring stops against is set back about .180" further on the SVI than on the Dawson.

Edited by HDGoose
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8 hours ago, Don_B said:

Just my humble opinion but if you have an unaltered SV pistol that is having light strikes I would look everywhere else before I changed out parts. Type and brand of primers, seating depth, etc. 

 

i have put many hundreds of thousands of rounds through SV pistols and can honestly say the pistol was never responsible for light strikes. Adjustments that moved on my loaders were the biggest issues ( high primers) followed by certain brands of primers. 

 

Again, just my opinion.  And my experience. ?

 

 

 

 

I appreciate your opinion and experience but I'm relatively confident that high primers aren't the problem. I could definitely be wrong but I'm confident that my reloading and inspection routine is solid. I'm running Winchester small pistol primers - which I ran over 15k of through my STI last year with zero problems. My STI has a lighter main spring (17lb vs 19lb in the SV). The most obvious difference between the guns is the much shorter FP.

 

I'm not sure there is anything wrong with the gun at all as the number of light strikes is pretty low - maybe 15? I guess I'm hoping the extended firing pin could possibly make the gun a little less sensitive to primer variables?

 

7 hours ago, OPENB said:

Main spring weight? Cheapest & easiest fix, check it after primers.

 

19lb.

 

7 hours ago, xSTONESx said:

I have had great luck with uncut  Wolfe extra power FP springs and stock SV firing pins in all 3 of my infinity pistols.

 

As Don_B said, primer seating depth and brand could play at part in this.

 

Whats the round count on the gun? Have you ever changed the main spring?

 

I don't know the round count but it is low. I bought it used from another Enos member and it looked absolutely brand new. I've run just under 1800 rounds through the gun so far. I have not changed the main spring.

 

 

 

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Check your ibf screw is not loose. I have seen phantom light strikes appear in svi and it was loose ibf. It uses a 1/8 hex key from memory. Put one down the firing pin tunnel and ensure its tight. 

 

I run the sv pin in my sv. It has the firing pin spring cut as per sv instruction (they specify to leave x number of coils past the head of the pin). 

 

My trigger is just under 2lb and hammer spring is either 17 or 15 (I think it has the 15 in there). No light strikes ever though I only run federal spp and srp. 

 

Other things in the system can also contribute to light strikes like a short hammer strut or bent hammer strut. But I'd check the ibf first. 

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"Check your ibf screw is not loose. I have seen phantom light strikes appear in svi and it was loose ibf."

"But I'd check the ibf first."


And we have a winner! Thanks for the pointer Baron - the screw didn't seem to be backed out but it wasn't even finger tight. Cleaned the threads and gave it a drop of blue loctite. Hopefully that'll solve it. I'm betting it could also help the erratic ejection I've been seeing.

I think I'll order an extra screw or two and begin checking to make sure the screw is tight each time I clean the gun.



I may still try the extended FP but I want to see what it'll do with the stock pin for now.


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Ding ding ding! :)

 

can you please tell my wife that on occasion I am right?

 

most often when I've seen head scratching light strikes in an ibf gun it was the screw backed out (doesn't have to be much). One guy didn't even know he had an ibf so it would have taken him a while to figure out!

 

I'm glad I could be of some help. The stock sv pin seems to work well as long as we remember to cut the spring to the length sv reccomend. 

 

I also carry a spare ibf screw but I carry lots of spares...

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Well, it turns out that tightening the IBF was not the solution to all of the problems. Prior to a big match last weekend I test fired one magazine with the Dawson extended firing pin and shortened FP spring so that I would at least know whether or not it would work for a backup if needed. Luckily it did work because on the 2nd stage of a 20 stage match (roughly 50 rounds in) I had two light strikes again. Switched to the Dawson between stages and the gun ran great for the remaining 18 stages (roughly 700 rounds). I think I'll stay with the extended pin from now on.

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If your IBF screw was loose and you ran a bunch of ammo then the screw is possibly damaged. If the screw is damaged then the longer firing pin only temporarily solved your problem again. I would remove the screw and inspect it, replace if necessary. If the screw is damaged and you continue to use it the damage can worsen and that is no bueno.

 

I'd bet a shiny nickel that the gun will run with the standard FP if there was no problem or you solved the problem. I am sorry but I don't believe the pistol is repaired, yet. 

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If your IBF screw was loose and you ran a bunch of ammo then the screw is possibly damaged. If the screw is damaged then the longer firing pin only temporarily solved your problem again. I would remove the screw and inspect it, replace if necessary. If the screw is damaged and you continue to use it the damage can worsen and that is no bueno.

 

I'd bet a shiny nickel that the gun will run with the standard FP if there was no problem or you solved the problem. I am sorry but I don't believe the pistol is repaired, yet. 


I'm going to order a replacement screw tomorrow but mainly just to have a spare. I did examine the screw closely and there is nothing visually wrong with it.

I'll let you keep you nickel. You may be right and I may be able to get the gun to run 100% with the stock FP but frankly I don't see anything wrong with running an extended pin. It seems like cheap insurance against light strikes to me.


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yeah there's no real drama with running a longer pin. the only minor 'issue' is that because of the spring space taken up by the IBF the stock SV pins have the 'shoulder' on the pin further back to allow a decent FP spring length. when using another makers pin you'll have to cut probably 1-2 more coils than you do with the sv pin. not a big deal.

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yeah there's no real drama with running a longer pin. the only minor 'issue' is that because of the spring space taken up by the IBF the stock SV pins have the 'shoulder' on the pin further back to allow a decent FP spring length. when using another makers pin you'll have to cut probably 1-2 more coils than you do with the sv pin. not a big deal.


So does the factory SV pin also require trimming of the FP spring?


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Yes.

 

Right down the bottom on here:

 

http://www.sviguns.com/4007.php


 

Quote

 

The firing pin channel on an Infinity slide with Interchangeable Breechface is shorter than a standard 1911. The firing pin length is standard, however, the firing pin spring must be cut to a length where the end of the spring is flush with the tip of the firing pin when the spring is fully seated on the firing pin.


 

 

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Well crap - there's the problem. I had read somewhere (or maybe misunderstood what I read) that trimming the FP spring was only necessary when running a non SVI firing pin - so I've been running a stock length Wolff spring which is likely causing coil binding and occasional light strikes.

 

So let me make sure I have this straight:

For an IBF gun FP spring should always be trimmed to " flush with the tip of the firing pin when the spring is fully seated on the firing pin". Non SVI pin will require additional trimming because of the shorter length from end of pin to shoulder. Is that about right?

Edited by HDGoose
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