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Discussion Starter · #1 ·
Going to be a bit of background story to help diagnose. Since I built my 2nd AR the new setup has had some light primer strikes. To give some background my first AR had a RRA 2 stage in its lower. That setup worked fine, never had a problem with striking light. On my new setup I moved the RRA 2 stage to it, and move the single stage that was in this to my other AR.

FYI I did make sure the hammer spring wasnt backwards on the reinstall of the 2stg, as this is a common mistake, and it is in correctly. This is strange because the 2stg was working great in the previous setup, but now its light striking occasionally. What I did was switch lowers on the 2 rifles. Shot off about 20 rnds with no problems in the suspect lower. So that begs the question could anything in the upper cause a light primer strike? Ive checked the BCG in and out and nothing seems out of place. However I have not tried shooting the single stage on the new upper.
 

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Is it possible the hammer is striking the bottom of the BCG? by bottom i mean bottom front in front of the firing pin. Or is your firing pin worn, or out of spec? Just a few suggestions. Good luck!
 

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Discussion Starter · #4 ·
the suspect BCG is brand new from bravocompany. When I am shooting sometimes I can go a whole mag without a light strike then one mag I had 3-4. When i recycle the lightly struck round it goes boom.
 

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Hammer it might be hitting the BC. I got a trigger job DVD and it happened on one of the guns he used in the DVD. He put a bevel on the hammer then it worked,

Thanks,Keith
 

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If I remember correctly, (always suspect) about the only things that can cause lite strikes are a very dirty carrier group with carbon everywhere, the carrier not fully setting forward and the hammer hitting or nicking the carrier and not the pin...

...and finally just a bad or distorted hammer spring. Also a lower probability is a bad firing pin or cam pin. Is the carrier group completely assembled? Missing cotter pin? Try an experiment. When you get a lite strike, punch the assist.

Watch the carrier to seess if it goes forward even a little bit. Let's thank the design team that makes (usually) the rifle platform very safe to shoot. You don't want the carrier hanging up as everything must be in battery for the pin to be exposed.

Usually one would think that a dedicated upper has the necessary compatablity in its components. I am confused; is the stock trigger causing the lite strikes, or is it the aftermarket 2 stage trigger? You only changed the lowers? Humm. HB of CJ :) :) :)
 

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Discussion Starter · #7 ·
I'll make up some names for my ARs: PlainJane (PJ) and Tacticool (TC). I originally started with PJ lower and upper with a 2 stage RRA. Never had a problem on that. Later I built a second AR which started with a single stage. I moved the 2stage from PJ to TC, and the single to PJ. During zeroing of TC upper and lower I encountered the light primer strikes. Later to troubleshoot this I moved TC lower to PJ Upper. No light primer strikes. However I did not try to investigate TC upper on PJ lower.

I dont suspect a dirty carrier group because TC was brand new during zero, and I dont suspect the 2 stage RRA due to it working previously in PJ without any problems.
 

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I'll make up some names for my ARs: PlainJane (PJ) and Tacticool (TC). I originally started with PJ lower and upper with a 2 stage RRA. Never had a problem on that. Later I built a second AR which started with a single stage. I moved the 2stage from PJ to TC, and the single to PJ. During zeroing of TC upper and lower I encountered the light primer strikes. Later to troubleshoot this I moved TC lower to PJ Upper. No light primer strikes. However I did not try to investigate TC upper on PJ lower.

I dont suspect a dirty carrier group because TC was brand new during zero, and I dont suspect the 2 stage RRA due to it working previously in PJ without any problems.
I'm going to guess it's not anything in the lower. I'd suspect one of the things that has been suggested.

Firing pin out of spec, or hammer hitting the bolt carrier somewhere.

Did you try swapping bolt carriers?
 

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Discussion Starter · #9 ·
i havent done that yet. I'll have to find time to make a range trip to test it. I will probably try swapping either firing pins or BCGs. TC's BCG is a M16 bolt carrier group from bravo if that means anything.
 

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I'd double and triple check the hammer spring. The last 3 people that asked me about light primer strikes insisted the hammer spring was on right just to find out it was on backwards.
 

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Discussion Starter · #11 ·
yes ive checked the hammer spring, the spring arms are on the bottom part of the spring coil like shown that picture.
 

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Did you do the AGI trigger job?
 

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Discussion Starter · #13 · (Edited)
no trigger modifications. Only thing done to the triggers was purchasing them and installing them. I compared both firing pins last night and they were slightly different looking but the length was the same. That can be another thing to try out, swapping firing pins. I would like to keep the BCM M16 BCG in TC if possible.

I was also taking a look at how much the firing pin protruded thru the bolt when the bolt was compressed into the BCG. Didnt see anything that stood out but then again its really hard to see accurately due to the size.
 

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Discussion Starter · #14 ·
i did some testing this weekend: swapping around BCGs and firing pins b/t each gun. The problem didnt seem to move around with the BCG changes. I think the single stage isnt resetting properly, but it is clicking when the misfire happens. However when testing the reset with an empty gun it seemed to work. But the funny thing is the single stage didnt have a problem in the other AR it was installed in earlier. This is really bothering me.
 

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The problem didnt seem to move around with the BCG changes. I think the single stage isnt resetting properly, but it is clicking when the misfire happens.

Meaning that the hammer is dropping when you pull the trigger correct?

Have you tried a new hammer spring? or even an extra power hammer spring? That should be on your short list of things to try.

However when testing the reset with an empty gun it seemed to work.

Dry firing will do very little to nothing to diagnose the problem. If it's not together, or there's not a live round in the chamber, there's no way of telling if everything is working together like it's supposed to or if you're getting light strikes or not just by hearing a "click" sound (which could also damage your bolt stop and or other related parts in doing so).

But the funny thing is the single stage didnt have a problem in the other AR it was installed in earlier. This is really bothering me.

It's very hard to diagnose a problem like that on the web. It could be anything from what's mentioned above to the face of the hammer not being square, hard primers, bad lot of ammo, or a host of other things that we have no way of checking.

My best advice, If you're having a problem with something you just bought, send it back and try again.
 

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Discussion Starter · #16 ·
ill consider higher power hammer springs and see if the hammer face is square. I cant tell exactly if its coming from an actual strike or the small strike thats inherit in free floating pin.
 
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