Flustered!

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I went back to the farm with a new lower and my recently updated upper and I am flustered beyond words.

I have tried the yellow JP spring kits and it seems I always get a 50% Failure to Fire rate with them, but with subsequent tries, they always seem to go bang. This new lower I put together with the same Spike's Enhanced LPK, trigger adjuster screw and the JP Enhanced Reliability spring kit. This morning, my failure to fire rate was approaching 80%. I literally fired 4rds before given up and no matter how many times they were re-chambered, they just wouldn't go bang.

The lower that I originally put together for this upper has the factory Spike's springs and when I went to the neighbors down the street, I was able to fire 10rds of the ones I had tried at the farm with out a hitch using the same upper as I did at the farm.

Federal/American Eagle Black box 55gr FMJ 100% FTF
Barnes Vor-Tex 55gr 4rds fired

I was under the impression the Enhanced Reliability kit was designed to prevent this. It is the Yellow/Red spring kit.

Any ideas other than the springs, I am all ears. The only difference between the two lowers, are the trigger springs.
 
Originally Posted By: Orphanedcowboy
I was under the impression the Enhanced Reliability kit was designed to prevent this.

it is my impression also.

are you 100 percent sure you have the hammer spring in right? spring legs go over and above trigger pin?
 
Okay, which one?

These are hunting rifles and I was just wanting to zero a new scope. This lower will be for a 300 Black Out I am building. I am really considering just leaving the Spike's springs in, but i would like a little better trigger, not sure I need a sub 4lb trigger.
 
Originally Posted By: SlickerThanSnotOriginally Posted By: Orphanedcowboy
I was under the impression the Enhanced Reliability kit was designed to prevent this.

it is my impression also.

are you 100 percent sure you have the hammer spring in right? spring legs go over and above trigger pin?

Yes, just checked to make sure and it seems to me the hammer spring is very light, possibly out of spec?
 
Originally Posted By: OrphanedcowboyI went back to the farm with a new lower and my recently updated upper and I am flustered beyond words.

I have tried the yellow JP spring kits and it seems I always get a 50% Failure to Fire rate with them, but with subsequent tries, they always seem to go bang. This new lower I put together with the same Spike's Enhanced LPK, trigger adjuster screw and the JP Enhanced Reliability spring kit. This morning, my failure to fire rate was approaching 80%. I literally fired 4rds before given up and no matter how many times they were re-chambered, they just wouldn't go bang.

The lower that I originally put together for this upper has the factory Spike's springs and when I went to the neighbors down the street, I was able to fire 10rds of the ones I had tried at the farm with out a hitch using the same upper as I did at the farm.

Federal/American Eagle Black box 55gr FMJ 100% FTF
Barnes Vor-Tex 55gr 4rds fired

I was under the impression the Enhanced Reliability kit was designed to prevent this. It is the Yellow/Red spring kit.

Any ideas other than the springs, I am all ears. The only difference between the two lowers, are the trigger springs.

You can only use the RED spring with JP triggers!! You need to get the YELLOW spring kit and you will be golden like a shower.


ETA: I see you posted that you have tried the yellow kit before and had failures. I have the yellow kits in 4-5 lowers now and have only had 1 round fail to fire in any of them. I tried it 5 times and would not go so I chalk it up to a bad primer.

What primers are you using?
 
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I had a similar problem with an upper and bcg combo. Other uppers functioned on the same lowers.
My issue was corrected with a firing pin swap. Turns out protrusion was below spec.
Good luck and let us know how things turn out
 
Primers are what ever the factory uses, Barnes Vor-Tex and cheap American Eagle 223.

The bolt carrier group is the WMD Nickel Boron and the trigger is the Spike's Nickel Boron, both have been dry fired well over 500 using a drop block, average pull is 3lb 10oz.

I think the hammer spring is out of spec, it feels lighter than the yellow spring in another lower and way lower than the last lower I put together with a JP red hammer spring.

I am swapping it out with Spike's springs that come in the kit and returning them to JP to let them evaluate them. It sure doesn't feel right.
Thanks for the tips and help so far guys, just flustered to be 35 miles from a known good lower when you're wanting to have fun. Wind was dead calm and I had hung the plates at 200, 300 and 500rds to test the new M223 scope out on.
 
edit -

Never mind. I was going to suggest checking the hammer spring to see if it was backwards, but I see that you already checked that.
 
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Originally Posted By: coyotekillerNEGet a Geissele trigger and don't look back.

Yes +2 just buy a Geissele or Timney trigger and leave all the "Know it all's" to play with springs. I think the idea of having a rifle is when you pull the trigger it goes "BANG". Hard primers need a 4.5# hammer fall.
 
I've used several of the jp yellow spring kits. Only one gun did FTF and I had the hammer spring in wrong. Check that.
 
I checked it twice and it was right. I went back to the farm armed with 3 lowers and 2 extra JP spring kits, the yellow/yellow and the yellow/red. I tried it with several loads, 8rds out of 10 refused to fire on three tries. I pulled the red spring and replaced it with a new red spring and it was a night and day difference. Those 8rds all fired the first go round with the new red hammer spring. I then replaced the red spring with a new yellow spring, all 10rds fired. I swapped the "bad" red spring into a known good lower, the first 5rds failed to fire and I gave up. I looked at it and the spring coils were deformed compared to the other two lowers, the coils had gaps between them, where as the know good springs were tightly wrapped up against each other.

I think this particular hammer spring is out of spec. With the sheer volume that these are produced, I am sure it is quite possible one slipped thru the cracks.

Thanks for the tips and help guys!
 
ALG Defense Combat trigger is a great inexpensive trigger that will ignite primers when the hammer falls. The pull is not 'light' but it is crisp with no grit.
 
Originally Posted By: TnTnTnALG Defense Combat trigger is a great inexpensive trigger that will ignite primers when the hammer falls. The pull is not 'light' but it is crisp with no grit.

I use these with the grip screw and JP YELLOW springs. Mine break around 3#. Don't forget some heavy lube for the first 500 sear releases or so. It lets the parts be completely broken into each other. I've had great luck with this set-up.
 
I just put in 3 sets in lower i have,2 from pallmento armory supplied in there lower build kits,made a huge improvement in pull.
Other trigger kit cam from CMMG didnt help at all.
The hammer seams to be a little differant where the spring crosses from coil to coil.I may take a grinder to it.

I havent fire any rounds thru any yet,just going by trigger pull gauge.
 
Have a timney single stage that breaks at 3.7lbs.I like it a lot & have never had a malfunction. My buddy has geissele triggers in both of his and I have shot both.Get the geissele.My timney is good but not as smooth.same price.
 
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