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10/11/2012 4:15:06 AM EDT
I have a bcm upper that has always ran great but lately the bolt catch will not work all the time.
If I cycle it by hand it works just fine but in live fire it might work 10% of the time.
Mags are all new pmags and usgi mags with magpul followers.
Buffer is a spikes st-t2 been there since gun was built.
Here's the catch it started this after I changed out to a spikes chrome bcg ( sold old bcg )I don't know if the bcg could be the culprit or just happened at the same time.
Lower has maybe 2k on it.
Any ideas would be appreciated.
Thanks
10/11/2012 4:47:33 AM EDT
[#1]
Semi-auto carrier to a full-auto carrier? That's all I can think of that could have changed....maybe the extra weight of the fa carrier?

10/11/2012 4:53:48 AM EDT
[#2]
Both are auto
10/11/2012 5:09:00 AM EDT
[#3]
Things that I'd check"
1. Gas key is tight and staked.
2. Bolt carrier bearing surfaces are smooth and polished.  I've never used a chromed bolt carrier so I don't know if the chroming makes them tighter or not.
3. Lube, lube, lube.  I've had a couple of bolt carriers that needed 100 rounds or so to break in and function consistently.

If the gun is cycling fine, but not locking open, then it's probably that the bolt carrier isn't quite making it back far enough and that could just be a little extra friction.
10/11/2012 11:40:46 AM EDT
[#4]
How many rounds have you put through the rifle with the new bcg? Like it was said above it will more than likely have a break in period.
10/11/2012 12:08:45 PM EDT
[#5]
Replaced buffer spring and it is locking back everytime now
10/11/2012 2:23:34 PM EDT
[#6]
Quoted:
Replaced buffer spring and it is locking back everytime now


SURE! Ask for help then fix it yourself.  

Just kidding.  It's nice when it's a simple fix.
10/12/2012 5:27:41 AM EDT
[#7]
Quoted:
Quoted:
Replaced buffer spring and it is locking back everytime now


SURE! Ask for help then fix it yourself.  

Just kidding.  It's nice when it's a simple fix.



Yes it is.
Next thing I was thinking was your first suggestion the gas key.
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