Norc M4 Bolt Catch, Letting Go?

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skinnadoor

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Hit the range the other day, with my New Norinco M4, my friend also had his. As the shoot progressed, on his rifle the bolt was fully back and he loaded a mag... and the bolt catch let go and the bolt went flying forward. So i took my empty M4, engaged the bolt catch and banged the butt slightly on the table... and wham, bolt catch let go on it's own.

Has anyone else experianced this? His is weak for sure as it's letting the bolt go forward from the slight force of loading a mag, but on a US rifle, if you bang the butt on the floor will it also let go?

I know it's the bolt catch for sure because if you hold the bolt catch in with your thumb and bang it, it won't let go.

Would getting a US armalite replacement catch and spring solve this problem ?
"And don't say buy a US rifle...:cool:"

Thanks.
 
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I am having the exact same problem with mine, I just figured that's what I get for buying a norc LOL. I would love to replace bolt catch as well if possible, dosen't give you a good feeling when it slams shut even though it is unloaded as you are setting it down.
 
Are you using the original Norinco mags?

When you insert a magazine, it's the follower that lifts the bolt catch up so that it stops the bolt going forward.

If you install a loaded mag, the only thing holding your bolt catch up against the bolt is friction, so if it was not up there positively in the first place, it can let go easily.

This has nothing to do with the catch itself or the spring for the catch. In fact, the catch spring will tend to DISENGAGE the bolt catch ;)

Try real (non-chinese cr@p) magazines and the issue will probably go away.
 
Claven2 said:
Are you using the original Norinco mags?

When you insert a magazine, it's the follower that lifts the bolt catch up so that it stops the bolt going forward.

If you install a loaded mag, the only thing holding your bolt catch up against the bolt is friction, so if it was not up there positively in the first place, it can let go easily.

This has nothing to do with the catch itself or the spring for the catch. In fact, the catch spring will tend to DISENGAGE the bolt catch ;)

Try real (non-chinese cr@p) magazines and the issue will probably go away.
Click to expand...

Mine does it with PMAGs. You have to give it a pretty good whack, but yeah it will release. Kind of annoying. Not a deal breaker though, I have a MOA (with handloads) AR for $700!
 
Claven2 said:
Are you using the original Norinco mags?


This has nothing to do with the catch itself or the spring for the catch. In fact, the catch spring will tend to DISENGAGE the bolt catch ;)

Try real (non-chinese cr@p) magazines and the issue will probably go away.
Click to expand...

Well no, we are using P-Mags, it only happend on his rifle when loading a mag as well as bumping it on the butt with no mag in and the bolt back. On my rifle, there was no mag in and the bolt was back. The catch holds the bolt back by moving up and resting against/in front of the single bolt lug at the 6 o'clock position... you can see it plain as day.... a mild bump will release the bolt and let it fly forward.. it's almost like there is not enough spring pressure in the bolt catch to keep in place. It seems to me a stronger catch spring would solve this problem i'm wondering if anyone has tried, total cost in US parts to replace the catch, plunger and spring with US parts is around 20 Bucks. There is no wear or anything on either rifle. I'm deffinetly changing these parts, just wondering if anyone has done it yet.

Oh and by the way, I hit a beer can, 2 out of 5 shots at 100 yds, with the iron sights, it was dialed in for 100yds right out of the box. This M4 is super accurate.
 
skinnadoor said:
Well no, we are using P-Mags, it only happend on his rifle when loading a mag as well as bumping it on the butt with no mag in and the bolt back. On my rifle, there was no mag in and the bolt was back. The catch holds the bolt back by moving up and resting against/in front of the single bolt lug at the 6 o'clock position... you can see it plain as day.... a mild bump will release the bolt and let it fly forward.. it's almost like there is not enough spring pressure in the bolt catch to keep in place. It seems to me a stronger catch spring would solve this problem i'm wondering if anyone has tried, total cost in US parts to replace the catch, plunger and spring with US parts is around 20 Bucks. There is no wear or anything on either rifle. I'm deffinetly changing these parts, just wondering if anyone has done it yet.

Oh and by the way, I hit a beer can, 2 out of 5 shots at 100 yds, with the iron sights, it was dialed in for 100yds right out of the box. This M4 is super accurate.
Click to expand...

When you do change these parts please let me know if it solves your problem. Again, I am having the exact same problem. It is with no mag in that a bump can cause the catch to release. It has happened several times and I have only had it to the range a few times.
Thanks
 
I don;t think you understand me. A stronger spring on your bolt catch will make this more likely not less likely. The bolt catch spring is trying to lower the bolt catch, not raise it.

It's the magazine's spring that overpowers the bolt catch spring to engage it.
 
Listen to Claven's advice!

Skinnadoor,

Claven is correct in what he advised you regarding the bolt catch and spring.

The spring forces the bolt catch downwards, out of the way of the bolt, and holds it there.

If it worked the way you think it does, it would hold the bolt open after every shot.

It is the mag spring and mag follower that push the bolt catch upwards to hold the bolt open when the mag is empty.

A stronger spring in the mag catch will mean that the bolt may not lock back consistantly. There is probably something else causing this issue. I will look around, and come back with some possibilities.

Regards.

Mark
 
Possible causes.

Skinnadoor,

Non of the manuals I looked at list this as a specific fault, or any possible remedies for its occurrence.

Other issues involving the Bolt Catch, and remedies for them, suggest checking that it is assembled correctly, that the parts, including the BCG are to spec, without any damage or burrs, that there is no debris present, and the parts move freely.

Has anyone pressed the trigger while the upper and lower were separated, or the action was open? If this was done (usually has to be done a few times, but may happen with a single press) without restraining the hammer, or cushioning the fall, this can cause damage to the catch or frame, and may lead to this issue.

Regards.

Mark
 
Claven2 said:
I don;t think you understand me. A stronger spring on your bolt catch will make this more likely not less likely. The bolt catch spring is trying to lower the bolt catch, not raise it.

It's the magazine's spring that overpowers the bolt catch spring to engage it.
Click to expand...

Hey there Claven, you are bang on, after taking a second look at it. There is no damage on the bolt or the catch, and as MWL stated... the hammer was never let go to smack the reciever/catch. Since i got things a little backwords...... perhaps the norc spring is too strong, and the American one is the right tension. oh and MWL we tried 2 different Norc bolts in the same rifle and got the exact same results, which makes me think that the catch is suspect. The plan is still to swap it out with a US catch/spring and see what results i get. I think more then just a few shooters are having this issue, would love to rectify it. Thanks for the advice guys.
 
It is my understanding that all AR rifle will close the bolt when butt stock is bumped and there is no empty mag in place.

When the bolt is locked back with no mag, the catch is held by friction against the bolt face. The bolt face is held by a spring pushing on the BCG. If the rifle is bumped, the BCG moves back slightly against the spring. Once the slight movement occurs the friction holding the bolt catch is go and it's own spring pushes it out of the way.

It's annoying sometimes, especially on ranges where you have to rack your firearm with the mag out and the action open. I bought a couple of mag blocks from Boonie Packer it part for that reason.

As for the bolt closing when you insert a mag, I am stumped. The follower of an empty mag should actually act to hold the catch in place (that is how the catch is supposed to be activated during firing). As for a loaded mag, it won't hold the catch in place but it also should not put any pressure on the bolt to release the catch.

I might have missed it above but is this happening when you insert an empty mag, loaded mag or both?

Does the bolt lock back on an empty mag when firing? If so, does the catch engage the front of the bolt lugs or the bottom of the BCG behind the bolt? (I have had this happen when messing with a BAL lever)

Assuming it catches on the front of the bolt lugs like it is supposed to, does the catch seem to engage more if you hold the bolt latch and cycling the charging handle?
 
Just a quick update. Installed an Armalite M-15 bolt catch, spring and plunger and the bolt no longer lets go when inserting mags. Still lets go when you bump it on the ground with no mag in, but the mag issues is solved, taking care of this safety issue.

Thanks everyone.
 
bolt catch issue

skinnadoor said:
Hit the range the other day, with my New Norinco M4, my friend also had his. As the shoot progressed, on his rifle the bolt was fully back and he loaded a mag... and the bolt catch let go and the bolt went flying forward. So i took my empty M4, engaged the bolt catch and banged the butt slightly on the table... and wham, bolt catch let go on it's own.

Has anyone else experianced this? His is weak for sure as it's letting the bolt go forward from the slight force of loading a mag, but on a US rifle, if you bang the butt on the floor will it also let go?

I know it's the bolt catch for sure because if you hold the bolt catch in with your thumb and bang it, it won't let go.

Would getting a US armalite replacement catch and spring solve this problem ?
"And don't say buy a US rifle...:cool:"

Thanks.
Click to expand...

I had the same issue with my AR 15 & mentioned to a Gunsmith here in Vancouver. According to the Gunsmith, that's how most AR15's bolt catch are made & not much can be done about it.
 
wanna re open this thread

has anyone found out what causes the bolt to let go after bumping the stock?

Happened to me today. I've been looking but with little success.
 
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