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PCC Doubling - Causes and Cures?


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I shot an indoor match this evening and my PCC decided to double on me, twice  I have a little over 2000 rds of 132 PF ammo run through it.

 

It doubled once on 24 rd stage 1 and then again on 32 rd stage 3.  No problems on stage 2.  Both times it doubled I was engaging a close target and really pushing the speed.

 

It has a PSA Glock magazine lower with Hiperfire 24c trigger with the heavy springs (for the lightest trigger pull) and a CMMG ambi-safety.  I installed KNS anti-walk/anti-rotate pins about 300 rds ago.  The trigger pull did degrade slightly when I installed the pins.

 

Inspection shows nothing unusual.  No strange wear, cracks, chips or peening of the hammer or disconnector.

 

Ideas on what is causing the doubling and more importantly, ideas on cures?

 

Thanks.

 

Bill

Edited by Flatland Shooter
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Were you riding the sear?  I have seen in pistols that some individuals with very light triggers barely let the sear reset sometimes called riding the sear which always the gun to double.

 

Not sure if it is applicable to the PCC.

 

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9 minutes ago, pjb45 said:

Were you riding the sear?  I have seen in pistols that some individuals with very light triggers barely let the sear reset sometimes called riding the sear which always the gun to double.

 

 

I'm not sure.  It is a very light trigger and I felt I was fulling releasing the trigger between shots.  I plan on hitting the range tomorrow afternoon and see if I can get it to do it again.  The second time it doubled it sort of felt like it fired when I pulled the trigger and then fired a second time when I released the trigger.

Edited by Flatland Shooter
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I hope you are right Eric.  All shots were on target.  This morning I'm cleaning out the lower with some carb cleaner and blow it dry with air.  Lube it up a bit and take it to the range.

 

I'll shoot a couple of bill drills and see what happens.   A friend with a little slower trigger finger will join me and see if it does it for him too.

 

Do you thinkj going to the softer springs (increased trigger pull weight) might cure the problem if it bump fire?

 

Thanks.

 

Bill

 

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I was at a 3G match here when a competitors gun double, tripled, etc until the mag was empty.  I was RO'ing the guy.  He was a Vietnam Veteran, and had absolute control during the entire mag.  He left the range and went a purchased a new fire control group.

I went home and cleaned my shorts.

 

I did not know a slam fire would only result in one extra round being fired.

 

 

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Made it to the range this afternoon.  Ran a bunch of Bill drills and it did not double even once.  (It did kind of wear on my nerves not knowing if this would be the one to scare the crap out of me or not.)

 

Just to be safe, for a while I only loaded six rounds in the magazine each time.

 

But now I'm having problems with trigger reset.  Out of  roughly 120 rds fired, the trigger did not reset 5 times. 

 

Now what do I do?  Is it possible I wore out a Hiperfire trigger in just a few thousand rounds?

 

Bill

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1 hour ago, Patrick Scott said:

With all the stuff I have been through I found that a combo of heavy buffer+spring and light trigger would double if I was at all loose on the gun. 

 

 

I'm not running a heavy spring or buffer.  It got the stock PSA 9mm spring and 9mm buffer (5.2 ounces if I remember right).

 

I do have a buck and a half in change behind the recoil spring but its been in there since the beginning.

 

As for holding it loose, my quest for speed may have resulted in me not keeping a really good grip on the gun.  Aircooled6racer also mentioned this in a PM.

 

Its something I'll watch.

 

Thanks.

 

Bill

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I read a message somewhere on here where Hiperfire stated they are OK with the idea of us using their triggers in these guns. Give them a shout, see what they say.

Oddly enough though, putting a Hiperfire ECL in my particular 9mm AR stopped doubling. Was running a JP EZ kit before that and would get doubles/triples with certain hand loads . These guns are strange sometimes. 

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I know everyone wants the best trigger they can get in their PCC, but this is the reason I'm running a light polish on factory FCG, with JP yellow springs. Just not worth what the OP is experiencing, it's much cheaper, & 100% reliable. It's still a decent trigger for pistol bay shooting. We aren't shooting these at 400 yards on a 6" plate!

I'd agree with you that it could just be how you were holding it, except the failures to reset. I bet if you change triggers, you won't have anymore problems. 

Edited by OPENB
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12 minutes ago, OPENB said:

I know everyone wants the best trigger they can get in their PCC, but this is the reason I'm running a light polish on factory FCG, with JP yellow springs. Just not worth what the OP is experiencing, it's much cheaper, & 100% reliable. It's still a decent trigger for pistol bay shooting. We aren't shooting these at 400 yards on a 6" plate!

I'd agree with you that it could just be how you were holding it, except the failures to reset. I bet if you change triggers, you won't have anymore problems. 

Yup, exactly why I carry a ALG ACT with JP springs reading to go in my range bag if my Hiperfire fails me.

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9 minutes ago, Nathanb said:

I'm just really surprised we haven't seen dedicated Pcc triggers done yet. The market is there 

Somebody might be working on it, but the amount of variables in these guns(bolts, bolt speed, buffer, buffer spring, upper to lower fit, ect.) would make it real hard to build a one-size-fits-all PCC trigger I think. 

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The first place I should have checked was the Hiperfire website.  i found a trouble shooting FAQ that addresses both of my issues.

 

From their experience, both doubling and failure of the trigger to reset can be the result of a worn trigger pin hole.

 

My plan is to pull the Hiperfire trigger and put it into a brand new 9mm lower and see if that solves the problems.  If it does, it means some of these lowers can developed egged out trigger or hammer pin holes in as little as 2000 rds.  In my case it was with 132 PF loads.  Folks shooting hotter factory ammo may get even less life out ot their lowers.

 

The anit-walk/anti-rotate pin sets may prolong the life of the lower but in my case it would appear to have been too little too late.

 

Bill

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3 hours ago, Flatland Shooter said:

The first place I should have checked was the Hiperfire website.  i found a trouble shooting FAQ that addresses both of my issues.

 

From their experience, both doubling and failure of the trigger to reset can be the result of a worn trigger pin hole.

 

My plan is to pull the Hiperfire trigger and put it into a brand new 9mm lower and see if that solves the problems.  If it does, it means some of these lowers can developed egged out trigger or hammer pin holes in as little as 2000 rds.  In my case it was with 132 PF loads.  Folks shooting hotter factory ammo may get even less life out ot their lowers.

 

The anit-walk/anti-rotate pin sets may prolong the life of the lower but in my case it would appear to have been too little too late.

 

Bill

Wow, wonder if it's the specific brand of trigger causing the wear or the heavy movement of the blowback PCC system? Wonder if a billet lower would wear differerently? 

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Also, as trigger and bolt wear a bit, it may be that your bolt is just not contacting the hammer enough to get it fully reset. Different bolts interact with the various triggers differently. Most triggers that are solid AR10-worthy triggers, can work fine in the PCC's but they still depend on the bolt for reset. If the interaction between bolt and trigger isnt right though...

Edited by wgj3
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2 hours ago, Aircooled6racer said:

Bill: I just helped another guy who was having trigger problems also. Have you checked that you are not getting bolt bounce causing the doubling? Maybe try a lighter buffer spring setup. Thanks, Eric

 

It will just take a few seconds to switch out the PSA 9mm buffer (5.2 ounces if I remember correctly) and the spring with an H1 carbine buffer (3.8 ounces).

 

I can see where this might help with the doubling.  Can it also help fix the trigger failing to reset?

 

I also have some quarters behind the recoil spring.  I'll pull those out at the same time and see if it helps.

 

I planned on moving the Hiperfire 24c to another 9mm lower but will hold off until I can give these ideas a try.

 

Thanks.

 

Bill

Edited by Flatland Shooter
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42 minutes ago, wgj3 said:

Also, as trigger and bolt wear a bit, it may be that your bolt is just not contacting the hammer enough to get it fully reset. Different bolts interact with the various triggers differently. Most triggers that are solid AR10-worthy triggers, can work fine in the PCC's but they still depend on the bolt for reset. If the interaction between bolt and trigger isnt right though...

 

I have the same trigger in two other rifles (.223) and pulled the uppers to see if there was any difference in the appearance between the triggers.  I was looking for areas of uneven or unusual wear.  Other than a little more wear (removed bluing) on the left side of the disconnector hook on the hammer, all three FCG's appear identical.  I also tried two different bolts thinking there might be a little difference there.

 

Thanks.

Bill

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Hi Bill, I use the 24C and it breaks at 2 1/4#.   5.5 buffer, 130 to 135 PF ammo, .308 heavy carbine spring...and it did the same thing yours is doing.   My bolt was bouncing.   Upon the recommendation of a well respected forum member, I swapped out the .308 heavy carbine spring for a standard .223 carbine spring...and problem solved!   I could never have figured that out on my own; these PCC's are a tricky lot.   Thank you once more Eric, your freely given expertise is much appreciated. Thanks, Paul   

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