Bolt does not stay open after last round

[marching]

I have a new POF .223- less than 500 rounds cycled. I have had an issue with the bolt returning(not staying open) after the last round is fired. I have only used Magpul magazines, and it does not happen everytime.

I've been told to mess with the magazine spring as they are not strong enough, the upper looks great, and operates awesome-expcept for this obviously...I'm hoping it's a magazine issue.

Has anyone had similar problems? This is my first AR, so I'm working with minimal(none), knowledge.

Thanks advance.

 

[Hellbender]

Re: Bolt does not stay open after last round

Number your mags, so you can see if it just one mag that causes it.

Underpowered ammo or improper handloads can also cause this. Try different ammo.

These are the most common problems.

 

[DPontius]

Re: Bolt does not stay open after last round

If you are running an adjustable gas block, it could be underadjusted...try opening it up more. If not, give one a try. Noveske and JP make nice ones that let you regulate the gas flow into your action, which could allow you to increase the amount of flow currently present from the factory gas block

 

[dlxcupid]

Re: Bolt does not stay open after last round

did you run some sort of heavy buffer or heavy buffer spring? During the course of my build, the wolff power spring gave me problems with holding the bolt open with the last round. I ran a regular carbine spring and voila! problem solved. If that's not the case, I'd call POF.

Also, what kind of ammo are you running?

Here's the post I started when I had my problem:

http://www.snipershide.com/forum/ubbthre...393#Post2525393

 

[3O8Junkie]

Re: Bolt does not stay open after last round

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hellbender</div><div class="ubbcode-body">Number your mags, so you can see if it just one mag that causes it.

Underpowered ammo or improper handloads can also cause this. Try different ammo.

These are the most common problems.

</div></div>

This

 

[KYS]

Re: Bolt does not stay open after last round

I'd say it is your mag as stated before. Usually the follower is worn down or they are just designed to not lock open. You bolt catch in your lower might also be faulty. Both items cheap to replace if need be.

 

[KevinB-KAC]

Re: Bolt does not stay open after last round

As Hellbender said your gun may not be cycling fully. What ammo?

Easiest things first
#1 Number your mags
#2 check different ammo

 

[Captramrod01]

Re: Bolt does not stay open after last round

I had the same problem and it ended up being the bolt release. Guess it wasn't to spec or something because I replaced it and now it holds open every single time the mags empty. Also using pmags.

 

[Inogame]

Re: Bolt does not stay open after last round

I'd check the mags first, separate the lower from the upper and put an empty mag in. The bolt release should engage. Just give it a good eye.

Try it with a P-Mag and then a normal mag, note any difference. If you followed Hellbender's advice you might know which mag has the most problems compare that with a mag that seems to be working properly.

If there isn't a noticeable difference I'd look to buffer/spring or Gas issues next.

When a mag empties and the bolt returns to closed what happens if you pull the charging handle? Does the bolt lock back?

 

[johngfoster]

Re: Bolt does not stay open after last round

This problem can be caused by:
1. Weak mag spring (unlikely being it's Magpul, but not impossible)
2. Weak powered ammo (not enough gas pressure to cycle the action completely)
3. Gas leak somewhere--look at gas key bolts coming loose (again not enough gas pressure to cycle the action)
4. Too heavy buffer or buffer spring--doesn't allow the buffer/BCG to be cycled completely.

 

[Powder_Burns]

Re: Bolt does not stay open after last round

<span style="font-weight: bold">Make sure your bolt catch isn't binding or anything weird going on</span>. The bolt catch spring pushes your catch down so the carrier will clear it. The magazine follower is supposed to push the bolt catch up when the magazine is empty, and cause the carrier to engage with the bolt catch. Test the rifle with all your mags, and different loads. Load 1 round, fire gun. If the bolt catch engages, go to the next mag. Mark all the bad ones if it turns out to be a magazine related issue. If its not the ammo or the mags, its probably down to springs or gas system issues.

 

[msalm]

Re: Bolt does not stay open after last round

How about a simple lube job? Lube up the carrier, receiver extension (buffer spring) and make sure the rifle is working slick as snot. If it feels gritty at all or is dry they will short stroke a bit.

 

[Captain Moroni]

Re: Bolt does not stay open after last round

While a heavy buffer or spring could be the problem it could also be the solution. If your over gassed your BCG might be moving to fast for the bolt catch to engage, I have seen this happen before.
If you have tried everything else and you have a standard buffer and spring you might try a heavy buffer.

 

[marching]

Re: Bolt does not stay open after last round

Thanks to all for the advice- been away from the computer. I'm planning to visit the range this weekend to test the above suggestions.

Will update. Appreciate the efforts.

 

[vinconco]

Re: Bolt does not stay open after last round

One more suggestion. I had the same problem a couple weeks ago. Mag worked in every gun except the newest build and we just installed a lighter bolt catch spring, worked like a charm.

 

[Austincqc]

Re: Bolt does not stay open after last round

My roomate just got his POF and the Pmag that came with it doesn't hold trip the bolt catch. I looked at it and stripped the mag to see if there was something preventing the follower from lifting up, reassembled and when we took apart his rifle to see the magazine and the lower alone, the bolt catch completely misses the rear of the follower. I pulled some of my USGI mags and they worked just fine, some of my Pmags BARELY get caught by the catch. When I took out my AR and compared both bolt catches, his is significantly shorter (a few MM) and can easily be seen by the naked eye.

Did the OP send his lower back to POF? maybe they had a short run of out of spec bolt catches?

 

[hyena74]

Re: Bolt does not stay open after last round

i had this problem on an old rock river. it would only do it using pmags...but steel mags would hold it open.

funny thing is the pmags would work on other guns???

 

[Mr Joshua]

Re: Bolt does not stay open after last round

I would check the gas block like Leroy said. A friend of mine owns a POF and had it set to suppressed. He would have a lot of malfunctions including the bcg not locking out on the last round.

 

[scotharr]

Re: Bolt does not stay open after last round

Couple of thoughts:

Since it is successfully cycling all your rounds and only failing to lock back, that mostly eliminates "under-gassed" as a problem.

As stated, it is quite possible that you are over-gassed. In this scenario, the BCG cycles too quickly and the bolt catch fails to work. This happened to me when using a suppressor. The solution was to use a Tubb CWS to slow down the BCG and reduce bolt overrun: it worked perfectly.

You've had lots of comments on magazines and that is pretty easy to troubleshoot. Try a variety of magazine types and look for any patterns of failure.

Lastly examine the bolt catch & spring.

 

[kstraughen]

Re: Bolt does not stay open after last round

I had this same issue. Checked the mag catch and magazine. Ended up being the Buffer was wrong size. I ended up calling DPMS and speaking with a someone in parts. they helped me out.

 

[USACS]

Re: Bolt does not stay open after last round

Try a few different kinds of mags to eliminate mags a problem.

With that said, I'm starting to read about a lot more POF malfunctions. I also saw a POF P415 go tits-up big time a couple weeks ago. I'm starting to question POF's quality control.

 

[Austincqc]

Re: Bolt does not stay open after last round

Well we took it to an AR shop to try out different mags. We went through 15-20 mags with only 2 that would trip the bolt catch!! When I say they tripped it, if the bolt catch was tilted to the rear, they missed the follower and wouldn't stay open. There was enough play in the lower around the bolt catch to move it forward to catch or move it rearward and make it miss.

Even the guys at the shop that build uppers commented on how there was too much play.

The upper and lower rattle around a lot which shouldn't be the case with a $1700 billet upper/lower combo from the same factory when my forged upper/lower from different companies fits tighter. I think some QC issues in the latest run are evident.

I feel bad for my buddy that spent that much money. He has too much money and not enough knowledge to know what's going on. He's still happy and I'm being a good friend by keeping my mouth shut, but for $1700 a rifle should be 100%.