Extended Firing Pin Fitting

[ihatepickles]

I have a CZC SP01 Shadow Target. It's got a 13 lbs mainspring, a standard firing pin with a standard firing pin spring. While doing some load development with WSP primers I got 2 light strikes in about 100 rounds. So, I looked to install the extended FP that I'd ordered along with the pistol.

The numbers:

Standard pin was 2.467" in length and 2.435" from the firing pin stop to the tip.

Extended pin was 2.499" in length and 2.445" from the firing pin stop to the tip.

In other words, the extended pin was +.032" longer in total length, and .010" of that was on the front part of the pin between the firing pin stop and the tip. The extra .020" was obviously on the back end of the pin which protrudes from the firing pin stop.

With the extended pin installed, I held a straight edge to the firing pin stop to simulate the hammer being down. The tip protruded from the breechface by .009". I didn't feel safe with that condition. I took .009" off of the back end of the firing pin so that the pin wouldn't protrude from the breechface. This still leaves the extended pin .013" longer at the rear and .010" longer at the front.

To shorten the pin, I used 120 grit sandpaper and worked slow, being careful not to let heat build up. Once I got close, I chucked the pin into a drill and spun the back end of the pin on an Arkansas stone. I took care to maintain the domed profile. Once I was at the correct length I polished to rear of the pin with Flitz. I did a test fit and I was no longer protruding from the breechface. I cleaned and degreased the pin well and cold blued the part I worked.

Since I'd read a few topics about the extended pin without any conclusions or consensus on the topic, I wanted to put my results out there for everyone to see. I'd appreciate any thoughts on this, as I had nothing to go by except my own common sense. The protruding firing pin seems very unsafe to me, especially in light of the fully down hammer starts. How do the rest of the CZ fans feel about this?

I ran the extended pin for a match on Sunday, and had no hiccups or light strikes. From what I've read an extended pin shouldn't have been needed with a 13 lbs spring and WSP primers but for reasons I can't explain they happened to me. I always deeply seat my primers on my XL650. A RAMI firing pin spring is on order as well, might as well go all the way since I'm going to experiment with a <13 lbs mainspring at some point soon.

My concerns at this point are whether the extended firing pins are fully heat treated or just surface hardened. I'm going to keep an eye on the rear of the pin to look for any flaring due to repeated hammer strikes. Anyone have any information on this?

Steve

[poopshooter]

protruding pin does seem like a bad situation. i do hope that working that pin down doesnt shorten its life span. i use fed primers with the 13lb and standard pin. those all light, but when i used wsp i did get a couple that didnt touch off. when its time for you start experimenting sub 13lb, do you plan to clip coils or try a mainspring designed for a differant pistol? for a cz part the 13 is the lightest i have seen available.

[ihatepickles]

I know Cajun Gun Works has a light trigger kit with a 12 lbs and 8.5 lbs spring that they bundle with an extended firing pin.

With that said, I'll take a 13 lbs spring, compress it about 50% on a tight fitting guiderod chucked in a drill, and then spin it on some sandpaper to thin the steel. Clipping coils changes the spring's length which has implications beyond just the weight. Thinning the material evenly along the whole spring changes the weight only. I have built a few spring testers though so I have a repeatable way to know the parameters of my experiment.

I'm not sure which other firearms have a similar spec'ed mainsprings. If anyone has that info, please share.

[desman]

Your post definitely got me thinking.Ive noticed on my Shadow as well that when the hammer is fully down,that the extended FP does protrude a little.I did a small test one day and chambered a primed case.I gently tapped the back of the hammer with a wooden dowel and this definitely left an impression on the primer.While this didnt set off the primer it definitely made me leery of dropping the gun after LAMR!.I think that I may shorten the FP like the OP has done,good idea!Ive also noticed that with the light mainspring(13lbs),that there isnt enough force to push the hammer flat against the FP retainer,so it seems possible that a blow onto the hammer may get a bit of a "run up" to get the FP moving.What do others think?

[SteelShooten]

With the extended pin installed, I held a straight edge to the firing pin stop to simulate the hammer being down. The tip protruded from the breechface by .009". I didn't feel safe with that condition. I took .009" off of the back end of the firing pin so that the pin wouldn't protrude from the breechface. This still leaves the extended pin .013" longer at the rear and .010" longer at the front.

To shorten the pin, I used 120 grit sandpaper and worked slow, being careful not to let heat build up. Once I got close, I chucked the pin into a drill and spun the back end of the pin on an Arkansas stone. I took care to maintain the domed profile. Once I was at the correct length I polished to rear of the pin with Flitz. I did a test fit and I was no longer protruding from the breechface. I cleaned and degreased the pin well and cold blued the part I worked.

Since I'd read a few topics about the extended pin without any conclusions or consensus on the topic, I wanted to put my results out there for everyone to see. I'd appreciate any thoughts on this, as I had nothing to go by except my own common sense. The protruding firing pin seems very unsafe to me, especially in light of the fully down hammer starts. How do the rest of the CZ fans feel about this?

You've done it properly. Once these relatively hard small-rifle-primers I have are used up, and I switch back to WSP, I'll be doing the same thing.

I ran the extended pin for a match on Sunday, and had no hiccups or light strikes. From what I've read an extended pin shouldn't have been needed with a 13 lbs spring and WSP primers but for reasons I can't explain they happened to me. I always deeply seat my primers on my XL650. A RAMI firing pin spring is on order as well, might as well go all the way since I'm going to experiment with a <13 lbs mainspring at some point soon.

The XL firing pin will increase your reliability. Recognize that adjustments to the mainspring tension will influence the amount of time the pistol stays locked in battery.

My concerns at this point are whether the extended firing pins are fully heat treated or just surface hardened. I'm going to keep an eye on the rear of the pin to look for any flaring due to repeated hammer strikes. Anyone have any information on this?

The hardness of the pin should be consistent throughout. You may still see some -slight- deformation from repeated hammer blows until the impact surface work hardens.

[ihatepickles]

I've run 400 rounds through the gun with the modified extended pin. No malfunctions to report.

I examined the firing pin afterwards, there's a bit of peening on the back of the firing pin. I used a fine file to remove the small amount of mushroomed material and smoothed it with an Arkansas stone.

I don't like seeing that peening, but hopefully it's normal and won't continue to mushroom after the part is work hardened. There's no reduction in length due to the peening, measured to 2.4901" with a micrometer before and after. I'll keep a report going on this until I feel things are good to go (or not good to go).

[ihatepickles]

After a month running about 2000 rounds with the new firing pin, no more mushrooming to report. It seems like there was a small amount of it immediately after I did the work but then none thereafter.

[oddjob]

Did you use the regular firing pin spring or go to the extra power one (from CZ Custom site)?

[ihatepickles]

Did you use the regular firing pin spring or go to the extra power one (from CZ Custom site)?

The pistol arrived from CZ Custom with a stock length firing pin and stock firing pin spring with some coils clipped off.

I replaced the spring with a reduced power spring made for the RAMI, it's a $2 part from CZ USA. I wouldn't have minded buying the RAMI FP spring from CZ Custom, but they were out of stock when I made the order for my pistol.

You benefit more from the reduced spring, an extra power FP spring would make the pistol less likely to fire. There's a tradeoff though, the purpose of that spring is to prevent the pistol from firing full auto every time the slide falls on a live round in the chamber (and it won't stop until the mag is empty on a Shadow due to lack of a firing pin block). Be careful when you're swapping springs. I tested about 50 rounds of ammo by dropping the slide and then extracting the round and looking for slight indentations on the primer from the firing pin lightly tapping. I didn't see any evidence of that, and I still check occasionally.

Sorry for the scary disclaimer, I don't know everyone on the forums or their experience level. I don't want anyone to hurt themselves. That reason is why I thought I'd post my experiences with the extended firing pin, I was concerned people were just dropping this pin into their guns without checking for protrusion when the hammer was fully down on the back of the pin. As far as I'm concerned, this part must be fit to the gun and it's not a drop in-part.

So yes, the extended firing pin makes the pistol more likely to fire. The reduced power FP spring also makes the pistol more likely to fire. This hopefully will allow me to reduce the mainspring power a bit in search of a lighter double action trigger pull. If I can get things nice and reliable for say... a couple thousand rounds, then I'll trust it more.

[1SOW]

Mine on a 75B doesnt't protrude--original spring. No lite strikes with 13# main with two coils cut off using Fed or Win primers.. I was getting the same 2/100 with WIN as the OP.

Cajun Gun Works (CGW) makes and markets a new extended pin and matching light spring. His other kits and mods work well. he offers down to an ultra light (FED Primers only) 8# kit. Makes no difference to speak of with SA, but does in DA.

Edited December 14, 2011 by 1SOW

[eerw]

2.490 seems to be about the length you can go on the extended firing pin. I got a couple more things to check ( I am setting up on a firing pin block gun at the moment)

CGW ran some FP for me at 2.500 and they are definitely too long on a DA gun with the hammer down on the pin.

Also CGW has changed some of dimensions of his firing pin, so make sure you have the correct firing pin spring from him.

IIRC, the CZC ext. firing pins are coming just over 2.480