Bolt is moving too far forward when firing the last round of steel cased, does it with brass on one of my mags as well. Bolt catch is catching the body of the bolt carrier instead of the bolt face. Any ideas on what could cause it?
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Interesting AR Failure
- Thread starter dennism
- Start date
Bolt is moving too far forward when firing the last round of steel cased, does it with brass on one of my mags as well. Bolt catch is catching the body of the bolt carrier instead of the bolt face. Any ideas on what could cause it?
yes.
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It does. Will take a look at the gas block later this week. Buffer /spring combo is correct.
This does not happen on brass, except for on one mag.
Is it catching the lugs, or the carrier it's self from what i read...
Did you happen to change the buffer tube?
Did you happen to change the buffer tube?
I'm going to go with, Piece of Shit PSA Parts kit. What parts kit did you use?
![[rolleyes]](/xen/styles/default/xenforo/smilies.vb/042.gif "Roll Eyes [rolleyes]")
Could be that the spring behind the bolt catch or something else got behind it and is preventing it from compressing all the way.
Dream to Dream
NES Member
I've seen this before when too long of a buttstock screw is used, and the tail of the buffer impacts the end of the screw. Are you using a rifle stock, or some kind of CAR stock?
Dream to Dream
NES Member
I know you mentioned your buffer spring is correct, but it may be worth checking to make sure it is in spec. Should be roughly 10.5" long, 37-39 coils.
Also, what CAR buffer are you using? Standard, H, H2, H3...?
Also, what CAR buffer are you using? Standard, H, H2, H3...?
Dream to Dream
NES Member
I don't know. The fact that he can manually lock the bolt back properly, and that it almost always locks back when using brass ammo, is making me lean towards a cycling issue. Either under gassed, or too much resistance from the buffer/spring.
It looks to me like the bolt catch is not engaging properly. That has nothing to do with brass or steel case ammo but could be magazine dependent or it could be installed wrong. He wrote in the OP that the bolt moves too far FORWARD. That would not indicate the gas system to me.
Is it that the bolt stops too far forward because rearward motion is limited, thus not engaging the bolt catch properly? That would actually be under gassed, too heavy buffer or too strong a spring. Very tough to tell from the pic.
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I thought ar was 12.75" carbine 10.5"
If you have an iPhone, take slow motion video: Remarkably effective at diagnosing these things if someone can video you shooting. Load three rounds at a time in multiple mags and test the BHO on them in succession.
If he is racking the CH and the bolt catch is engaging as it should with all the mags I would tend to think the bolt catch and related parts/mag spring + follower are working as they should.
OP next time at the range chamber a round and drop the mag, fire while pressing the bolt catch in to see if it engages. Also are you running one of those BAD levers?
This isn't necessarily true at all: It could be installed in the correct orientation such that it engages manually but does not have enough tension for it to engage when the follower pushes on it. Tolerance stacking and all that great stuff. That would also indicate a magazine issue not a gas sys or ammo issue.
I'd number those mags, and start figuring out which one is having the problem. Sounds to me like its the bolt catch on the follower that is the issue. If you can fire flawlessly until then, I wouldn't see any reason to assume its a gas or buffer problem, otherwise you'd see the problem more often. And certainly more randomly.
You have it happen after the last round all the time, so regardless of brass or steel, I'd blame the bolt catch. Something is definitely up with that thing, if you ask me. A pic of the follower on the mag you think is causing the issue might help too.
You have it happen after the last round all the time, so regardless of brass or steel, I'd blame the bolt catch. Something is definitely up with that thing, if you ask me. A pic of the follower on the mag you think is causing the issue might help too.
This could be it too... If the spring in the mag is (somehow) crapping out. Or even if there is just a bunch of grit in the mag. It could easily prevent the follower from being pushed upwards enough to engage the bolt catch entirely. Again - find the mag, and take it apart and clean it, check it out, etc.
Dream to Dream
NES Member
Speaking from experience, the bolt catch has a much better grasp on the bolt face than the carrier. If it is catching the carrier but not the bolt, I'd be astounded if the bolt is cycling fully to the rear.
If it wasn't cycling far enough back to clear the bolt catch on the last round, it wouldn't be pushing the next round into the chamber during normal feeding either. At least not every time. He'd have problems with failure to feed as well, and he hasn't mentioned that being an issue.
Dennis if you want to meet me at the outdoor range again sometime we could try your upper on my lower to see if it cycles okay. Then that might be able to isolate whether it is a problem with the upper or lower. PM me if interested.
