Bolt Won't Stay Back

[Strider12]

Had a problem today where the bolt won't stay back after the last round or when I do it manually. Sometimes it'll catch for a second but as soon as I move the rifle it saps back. I tried different BCGs and the same. I built the lower and haven't had this issue before obviously.

Any suggestions?

 

[dial1911]

AR pattern rifle?

 

[KGmade]

if its not the bolt, it could only be a couple of other things. Does it fail with other mags? Does the bolt catch have good spring tension and move freely?

 

[Strider12]

if its not the bolt, it could only be a couple of other things. Does it fail with other mags? Does the bolt catch have good spring tension and move freely?

It won't stay back without mags. The mags I use have no issues in my other ARs. This seems specific to this lower.

 

[KGmade]

thats weird it wont stay back if you manually try it. Does the button feel harder to push than other lowers? The spring might be too strong, or the hole not drilled deep enough and its over powering the friction to hold to bolt back. What LPK did you use?

 

[Strider12]

thats weird it wont stay back if you manually try it. Does the button feel harder to push than other lowers? The spring might be too strong, or the hole not drilled deep enough and its over powering the friction to hold to bolt back. What LPK did you use?

Anderson lower, Anderson LPK. They are sending me a new catch and hardware.

 

[Wallace]

Anderson lower, Anderson LPK. They are sending me a new catch and hardware.

Just as an FYI, your bolt catch should have a tab on it that gets engaged by the mag follower. Take a pic of you bolt catch. My KAC SR-15 broke and caused this. I didn't notice it right away with my rifle.

Here is what I am talking about:

ETA: Also don't feel bad if yours did this. Mine broke on my $2K KAC factory rifle. The new part is just as shitty of a MIM part as the one you see below.

 

[Strider12]

Just as an FYI, your bolt catch should have a tab on it that gets engaged by the mag follower. Take a pic of you bolt catch. My KAC SR-15 broke and caused this. I didn't notice it right away with my rifle.

Here is what I am talking about:

ETA: Also don't feel bad if yours did this. Mine broke on my $2K KAC factory rifle. The new part is just as shitty of a MIM part as the one you see below.

View attachment 16983

Thanks man. I checked and all is good on that.

 

[DarthVader]

Thanks man. I checked and all is good on that.

If the catch isn't broken and you can't lock the bolt manually, then it sounds like either the lower or the catch is out of spec. How many rounds through the gun before this started happening?

 

[Strider12]

If the catch isn't broken and you can't lock the bolt manually, then it sounds like either the lower or the catch is out of spec. How many rounds through the gun before this started happening?

1

 

[DarthVader]

1

 

[Strider12]

Ya think Corky?

 

[DarthVader]

Ya think Corky?

I just hope it's not another "Anderson strikes again" situation.

 

[Cudruln]

1

Put a $ in front of that number and I will buy the headache from you.

 

[dial1911]

How much "front to back" play does the bolt stop have in the receiver slot?

 

[Wallace]

I just hope it's not another "Anderson strikes again" situation.

Yeah, their LPK's are super rough and their lowers have less than desirable for holes being nicely finished (or even drilled at all). Then again, what should I expect for $30? Everything but the springs in the kits I have used have been crazy gritty feeling and not very smooth installing. I mean they work, but there is a noticeable finished peice condition variance between them and even a basic PSA LPK.

 

[DarthVader]

Yeah, their LPK's are super rough and their lowers have less than desirable for holes being nicely finished (or even drilled at all). Then again, what should I expect for $30? Everything but the springs in the kits I have used have been crazy gritty feeling and not very smooth installing. I mean they work, but there is a noticeable finished peice condition variance between them and even a basic PSA LPK.

I've actually seen a handful that were truly out of spec, with issues like trigger / hammer pin holes drilled in the wrong location or the bolt catch pin hole drilled incorrectly (too low).

 

[ReservoirDawg10]

What kind of stock did you use? I have had this problem before and it drove me batshit until the light came on in my head. I was using a Magpul PST and the screw that holds the stock onto the buffer extension was too long. Rifle cycled fine, but the buffer was being stopped by the screw a cunt's hair prior to where it should have stopped.

 

[DarthVader]

What kind of stock did you use? I have had this problem before and it drove me batshit until the light came on in my head. I was using a Magpul PST and the screw that holds the stock onto the buffer extension was too long. Rifle cycled fine, but the buffer was being stopped by the screw a cunt's hair prior to where it should have stopped.

Had not thought of that. A short buffer tube could cause the same issue.

 

[ReservoirDawg10]

Had not thought of that. A short buffer tube could cause the same issue.

Shit - could be a short tube, but cutting the screw down worked. I replaced the damn mag release with 2 others, swapped uppers, etc. Finally occurred to me that it had to be somewhere in the extension just by process of elimination. Sounds like this could very well be the OP's problem as well.