PDA

View Full Version : AR Bolt not locking open on empty mag


SkryMun
05-23-2011, 9:25 AM
Hi all,

I have read through any post I can find regarding this issue with my recently completed build. So far what I've found doesn't seem to work.

I have a JD lower, DPMS parts kit, and an Adams Arms upper. When I insert an empty magazine the bolt catch comes up, but does not engage on the bolt. It looks like the bolt is catching on the magazine follower before the bolt catch can engage on the bolt.
When I eject the empty magazine, the bolt goes forward without the catch engaging.

I spent a few hours last week trying to modify the spring and bolt catch. I shortened the spring and I attacked the bolt catch with a dremel to see if I could encourage it to engage more firmly.

In the end, I am ordering a new spring and bolt catch hoping that this is just a bad bolt catch from the kit.

Has anyone seen an issue like this? Any suggestions?

Thanks in advance.

ke6guj
05-23-2011, 9:32 AM
did you try a different magazine? Sometimes its a bad mag that isn't putting enough upward pressure on the bolt catch. Does it work when you engage the bolt catch manually?

FrankDux
05-23-2011, 9:38 AM
TrY different mags, what ones are you using?

thekwyjibo
05-23-2011, 9:52 AM
It looks like the bolt is catching on the magazine follower before the bolt catch can engage on the bolt.
When I eject the empty magazine, the bolt goes forward without the catch engaging.



Try this, put everything together and see if the bolt can reach the catch without a magazine in it by pulling the bolt all the way back with the charging handle.

The reason that I suggest this is that it may not have anything to do with the bolt catch or the bolt but the buffer. Different types of buffers are of different links (rifle and carbine for example), you could be bumping the buffer into the back of the buffer tube before the bolt reaches the catch. I saw this myself on my mws when I switched from the standard stock and buffer tube to a Magpul UBR, I had to switch to a shorter buffer.
Damn thing would reach back just behind the follower but no to the catch the bolt face, instead catching on the face of the bolt carrier, the result is when I switched mags and dropped the bolt with the release it would not strip a round from the mag, I would have to pull the latch back manually that extra 1/4" farther (still not enough for the bolt face to reach the catch, but enough to catch a round). I took a look inside and realized what the deal was, ordered a short buffer from heavybuffers and the problem went away.

This could be something similar to what I had.

rero360
05-23-2011, 10:02 AM
The bolt catch is a cheap part but man, just say no to the dremel.

could be you have the wrong length buffer spring, wrong type of buffer, bad magazines or you are under gassed.

AR-15 Rep
05-23-2011, 10:15 AM
There could be a few things to check. Sometimes the bolt catch is not riding properly, or smooth in the lower. Could be the mag as well so its a process of elimination and checking things as you go...

dieselpower
05-23-2011, 10:22 AM
First of all... and this is for all readers....

The AR15 was designed by an Engineer Qualified in firearms design. He has done all the leg work and hard stuff...LEAVE YOUR FREAKING DREMEL IN THE TOOL BOX!

When your rifle is back to mil-spec, start the trouble shooting process based on a simple set of rules that are ALWAYS valid...

A) 11teen billion AR15s work with the standard parts, yours is no different.

B) If yours is not functioning, either you assembled it wrong or a part is bad... you are not going to redesign it to work.

C) If you are experienced enough to identify a malformed part, then you would not need our assistance. Unless you can clearly, and with 100% accuracy spot a problem that a dremel tool will fix..DONT DO IT.

Guys who cut springs are telling me one of two things...they screwed up and used the wrong spring in the wrong place. How are you going to "add" to the short one if cutting the long one fixed a problem? How about getting the right spring in the right place. One long spring means TWO springs are in the wrong place.

PoofNoEyebrows
05-23-2011, 10:26 AM
^ +1

SkryMun
05-23-2011, 10:51 AM
First off, Thank you all for your replies and assistance. I really appreciate you taking your time.

@ ke6guj and FrankDux I have tried several different pmags. I supposed I should see if I can get ahold of a different magazine from another manufacture.

@ thekwyjibo Yes, I can manually engage the bolt catch w/o a magazine in. It locks back, but if I bump it on the floor it will go forward. (One thread I read suggested cutting the spring to correct this issue, which is why I cut the spring)

@ deiselpower and PoofNoEyebrows You are right. I don't have the experience to identify malformed parts.
In my defense, by the time I broke out the dremel I already knew I was going to get a new bolt catch and spring so I figured I would experiment. I also was careful to remove the bolt catch from the lower when I worked on it so I would not be spreading shavings all over.

Again, thank you all for your time and help.

Super Spy
05-23-2011, 10:59 AM
I had this problem with my first AR build...it was due to crappy mags, magpul mags solved the problem.

Milspec714
05-23-2011, 11:30 AM
First of all... and this is for all readers....

The AR15 was designed by an Engineer Qualified in firearms design. He has done all the leg work and hard stuff...LEAVE YOUR FREAKING DREMEL IN THE TOOL BOX!

When your rifle is back to mil-spec, start the trouble shooting process based on a simple set of rules that are ALWAYS valid...

A) 11teen billion AR15s work with the standard parts, yours is no different.

B) If yours is not functioning, either you assembled it wrong or a part is bad... you are not going to redesign it to work.

C) If you are experienced enough to identify a malformed part, then you would not need our assistance. Unless you can clearly, and with 100% accuracy spot a problem that a dremel tool will fix..DONT DO IT.

Guys who cut springs are telling me one of two things...they screwed up and used the wrong spring in the wrong place. How are you going to "add" to the short one if cutting the long one fixed a problem? How about getting the right spring in the right place. One long spring means TWO springs are in the wrong place.

:iagree:

OUTSTANDING... couldnt say it any better or TRUER...

when all else fails go back to the basics... basics being done right the first time there will be NO second time

print this out use as reference...
http://www.ar15.com/content/guides/assembly/lower/lowerKit.gif

you can clearly see size difference in springs...

sacshooter1
05-23-2011, 11:44 AM
I had this same issue with a Adams Arms piston upper and a PWS enhanced buffer tube. I swapped out the buffer tube and the problem was solved for me.