I have an AR556, replaced the trigger and hammer springs w/ JP Enterprise 3.5 springs, now bolt does not lock open after last round. Everything else works great using the same mags and ammo as before. Is it the new springs or something else? If the springs are the issue, why? Anybody have any experience/knowledge on this issue? Thanks!
AR556 bolt not locking open after last round
- Thread starter guns4jrm
- Start date
steelshooterco
Single-Sixer
Sounds like a bolt stop issue, should engage rear of mag follower and stop bolt from going forward, could be stuck or rounded off. There is a spring and plunger in there. Changing out the hammer springs should have no effect.
The video in the earlier response shows how this work at just about the end and does a good job.
The video in the earlier response shows how this work at just about the end and does a good job.
Thanks for the info. I watched the video. Pretty cool!! It provided me with a much better understanding of the AR inner workings. It's a pretty new rifle and the bolt stop on my AR looks OK, no apparent damage. It locks up solidly when I pull the charging handle back and engage the bolt catch plunger. All new mags and the followers appear OK. I will give the rifle another good cleaning and take it to the range and see what happens. Thanks!
dfletcher
Blackhawk
guns4jrm said:
The bolt not locking open on the last round generally means the recoil impulse is insufficient - not enough gas pushing the bolt back. The bolt has to travel just a bit more to lock open when compared to just stripping a round. The hammer spring shouldn't make a difference, but there's an easy way to find out - reverse by putting in the factory original.
.
Bingo!
In view of the fact that he stated the bolt locks back when using the charging handle, I think you nailed his problem!
In turn, that could then be an indication of defective [weak] ammo or a leakage or a partial blockage in the gas system. Also, the buffer spring could be too stiff.
Thanks for the responses. I don't think its the ammo since I ran 5 different brands through it the last time at the range and all had the same result with the bolt not locking open on the last round (same 5 brands I used prior to changing out the trigger springs and no issues then). So it's either the springs for some reason or a partial blockage of the gas port. I will disassemble and give it a good cleaning and take it to the range again before I swap out the springs. I like the new springs much better than the oem ones, but if they are the problem then I will switch back.
steelshooterco
Single-Sixer
Be certain the hammer is not cocked (as firing it and hitting the lower can crack the lower).
Remove the upper from the lower.
Look at how the bolt latch moves.
Put in an empty magazine.
The bolt catch should be forced upwards and you would be able to press on it and force it back and froth against the pressure provided by the empty magazine spring.
Remove the upper from the lower.
Look at how the bolt latch moves.
Put in an empty magazine.
The bolt catch should be forced upwards and you would be able to press on it and force it back and froth against the pressure provided by the empty magazine spring.
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