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Locking Trigger Pins in Blowback PCC


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#1 Jesse Tischauser

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Posted 10 March 2017 - 10:47 AM

Thought I'd share this excellent bit of info from Mark Passamaneck

"Basically the force on the hammer pin in a blowback is significantly higher than in a DI or Piston .223. As such, that pin can start to egg out the pin hole. In a standard trigger geometry, that geometry then changes and it causes predictable issues. In a drop in, it is less, but the hammer pin still takes a lot more force than the trigger pin. When you use locking pins, you transfer some of that energy to the trigger pin and mitigate the egging out of the hammer pin. Basically, the locking of the two pins prevents rolling (galling) and more rigid structure to spread out the energy. Especially the guys who are trying to use low mass buffers and springs, the hammer pin forces are extreme in blowbacks. In the MPX, it does not matter."

#2 Tech

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Posted 10 March 2017 - 10:55 AM

Where's the link so they can take my money?



#3 Matt Rigsby

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Posted 10 March 2017 - 11:34 AM

KNS pins. Tony probably sells em.

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#4 Wall

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Posted 10 March 2017 - 12:02 PM

They've been out of stock.

Btw. They aren't necessary with a drop in cartridge type trigger like those from BoomerShooter sopnsor Timney Triggers. It's just the individual component types like a mil-spec, JP, Hiperfire, etc. that need the extra support.

I'd use them for cmc also because that sheet metal cage is flimsy.

#5 Flatland Shooter

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Posted 10 March 2017 - 02:15 PM

The folks at Hiperfire caution that anti-walk and anti-rotate pins can cause problems with their Hypertouch triggers.  

 

They recommend installing first with mil-spec pins then try the anti-walk or anti-rotate pins to see if the trigger pull is adversely affected.

 

https://www.hiperfir...-rotation-pins/



#6 MikeF

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Posted 10 March 2017 - 03:41 PM

They've been out of stock.

Btw. They aren't necessary with a drop in cartridge type trigger. It's just the individual component types like a mil-spec, JP, Hiperfire, etc. that need the extra support.
I'd use them for cmc also because that sheet metal cage is flimsy.


CMC triggers ship with their own anti rotation pins for this reason.

#7 Tuflehundon (Rob Gee)

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Posted 10 March 2017 - 03:57 PM

The folks at Hiperfire caution that anti-walk and anti-rotate pins can cause problems with their Hypertouch triggers.  

 

They recommend installing first with mil-spec pins then try the anti-walk or anti-rotate pins to see if the trigger pull is adversely affected.

 

https://www.hiperfir...-rotation-pins/

 

Interesting. I've been running KNS pins with my 24C for 2 years. 


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#8 Flatland Shooter

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Posted 10 March 2017 - 06:55 PM

Interesting. I've been running KNS pins with my 24C for 2 years. 

 

Good to know.  I knew about the problems with the hammer pin hole and wanted to add anti-walk / anti-rotation pins but with the 24c trigger, I did not want to be the first to experiment. 



#9 usmc1094

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Posted 10 March 2017 - 07:11 PM

I used KNS pins in my 24c all last year.

#10 Flatland Shooter

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Posted 16 March 2017 - 07:29 PM

Well I installed the KNS pins on my PCC last evening.  The result was a great trigger has become a good trigger.  Not what I wanted.  Ran just over 70 rounds through the gun this afternoon in hopes it would clean up.  But no change. As Hiperfire cautioned on their website, adding anti-walk/anti-rotate pins may degrade the quality of the trigger pull.

 

I'm sure there is nothing wrong with the KNS pins or the Hiperfire 24c trigger, but with the pins added it is now "slushy" possibly with increased trigger pull weight.  Nowhere as nice as it was when the 24c was first installed.

 

Now I need assistance/recommendations.

 

First, anyone that has put in the pins with a 24c trigger and continue to use them, was there a change in the "feel" of the trigger after adding the pins and in time did it improve?

 

Second, can anyone tell me how many rounds were fired in their 9mm PCC before they started having problems with the hammer pin hole egging out?

 

I need to decide to either accept the trigger as it is now or put the mil-spec pins back in and plan on replacing the lower receiver in time.

 

Suggestions will be appreciated.

 

Bill



#11 Wall

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Posted 16 March 2017 - 08:39 PM

Well I installed the KNS pins on my PCC last evening.  The result was a great trigger has become a good trigger.  Not what I wanted.  Ran just over 70 rounds through the gun this afternoon in hopes it would clean up.  But no change. As Hiperfire cautioned on their website, adding anti-walk/anti-rotate pins may degrade the quality of the trigger pull.

 

I'm sure there is nothing wrong with the KNS pins or the Hiperfire 24c trigger, but with the pins added it is now "slushy" possibly with increased trigger pull weight.  Nowhere as nice as it was when the 24c was first installed.

 

Now I need assistance/recommendations.

 

First, anyone that has put in the pins with a 24c trigger and continue to use them, was there a change in the "feel" of the trigger after adding the pins and in time did it improve?

 

Second, can anyone tell me how many rounds were fired in their 9mm PCC before they started having problems with the hammer pin hole egging out?

 

I need to decide to either accept the trigger as it is now or put the mil-spec pins back in and plan on replacing the lower receiver in time.

 

Suggestions will be appreciated.

 

Bill

The sprung detent inside those hiperfire triggers has a hella spring on them & that's probably where you're picking up the drag since the pin can no longer rotate.

 

Try swapping them & using the screwed (rotating) pin in the hammer & the other (slotted) pin in the trigger.

This will still keep the force of the hammer from moving the pin around & egging out the hole, but it will be able to rotate with the hammer.



#12 Flatland Shooter

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Posted 16 March 2017 - 09:00 PM

Thank you sir.  I will give that a try.



#13 Flatland Shooter

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Posted 17 March 2017 - 01:04 PM

On Tony's suggestion, I put the KNS rotating trigger pin into the hammer hole and the KNS non-rotating hammer pin into the trigger hole.   To allow the pin to rotate, I did not torque the screws tightly that go into both ends of the trigger (now hammer) pin to allow the pin to rotate.  I cleaned the threads, added a little primer and #242 Loctite to hold it together.

 

A few minutes before making the change, I installed the Mil-spec pins so the "trigger feel" was fresh in my mind.

 

The end result is Tony's suggestion improved the trigger feel.  It not quite up to the Mil-spec trigger feel but its close enough that I'm now a happy camper.  Plus I have the KNS anti-walk/anti-rotate pins in place to avoid future problems with the hammer hole egging out.

 

Thanks Mr. Wall

 

Bill



#14 Wall

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Posted 17 March 2017 - 05:50 PM

On Tony's suggestion, I put the KNS rotating trigger pin into the hammer hole and the KNS non-rotating hammer pin into the trigger hole. To allow the pin to rotate, I did not torque the screws tightly that go into both ends of the trigger (now hammer) pin to allow the pin to rotate. I cleaned the threads, added a little primer and #242 Loctite to hold it together.

A few minutes before making the change, I installed the Mil-spec pins so the "trigger feel" was fresh in my mind.

The end result is Tony's suggestion improved the trigger feel. It not quite up to the Mil-spec trigger feel but its close enough that I'm now a happy camper. Plus I have the KNS anti-walk/anti-rotate pins in place to avoid future problems with the hammer hole egging out.

Thanks Mr. Wall

Bill

Cool, happy to help

#15 Matt Rigsby

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Posted 17 March 2017 - 06:05 PM

Tony is a smart guy when it comes to guns, now ask him an algebra question.

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#16 Wall

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Posted 17 March 2017 - 07:02 PM

Tony is a smart guy when it comes to guns, now ask him an algebra question.

I'll get my 6th grader to field all the hard stuff




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