AR15 Bolt Catch question

[HollowPoints]

Here is the scenario.

I finish shooting my mags worth of ammo, the bolt locks back after firing the final round. Drop the mag and insert new loaded mag. If I slap the bolt catch/release it does not chamber a round, I have to manually rack the charging handle to chamber a round.

Does anyone know why my bolt isnt locking back far enough to chamber a round using the bolt release?

I am using a S&W Lower w/ RRA LPK, BravoCompany Upper/BCG/Charging handle, and DPMS Stock/buffer tube/spring.

Thanks for any help in advance.

-Tom

 

[Mr. Brownstone]

Are you loading your magazines to capacity? Are they ghey 10 rounders? Try loading two less. Sometimes fully loaded mags are too tight, and it wont grab a round. Or can you see that the bolt is forward slightly when it locks back?

I assume the rifle is cycling properly otherwise.

Have you tried a different magazine?

Does this happen every time, or just once?

 

[Rotaryrocket]

It's junk. Bring it over I'll take it off your jands

 

[HollowPoints]

Are you loading your magazines to capacity? Are they ghey 10 rounders? Try loading two less. Sometimes fully loaded mags are too tight, and it wont grab a round. Or can you see that the bolt is forward slightly when it locks back?

I assume the rifle is cycling properly otherwise.

Have you tried a different magazine?

Does this happen every time, or just once?

I have tried multiple mags, 10rnds, 20, 30, 40...all loaded to capacity and not loaded to cap. They all do the same thing. Rifle is flawless other than this problem.
This happens every time the bolt locks back.

The bolt is slightly forward compared to other AR15s and my AR10, all my other rifles chamber a round when using the bolt catch. You can physically see that the bolt isnt far enough back to catch a round on the way forward, hence why pulling back the CH and slingshotting it chambers a round, it pulls the bolt back just enough to catch a round.

I have no idea why the bolt wont lock back far enough and am hoping someone has the answer.

 

[Mr. Brownstone]

I have tried multiple mags, 10rnds, 20, 30, 40...all loaded to capacity and not loaded to cap. They all do the same thing. Rifle is flawless other than this problem.
This happens every time the bolt locks back.

The bolt is slightly forward compared to other AR15s and my AR10, all my other rifles chamber a round when using the bolt catch. You can physically see that the bolt isnt far enough back to catch a round on the way forward, hence why pulling back the CH and slingshotting it chambers a round, it pulls the bolt back just enough to catch a round.

I have no idea why the bolt wont lock back far enough and am hoping someone has the answer.

What are you using for ammo?

 

[Golddiggie]

Compare the buffer and spring from that rifle with those from your other AR15's. You could also try that upper on another lower to isolate the issue.

 

[jasons]

Here is the scenario.

I finish shooting my mags worth of ammo, the bolt locks back after firing the final round. Drop the mag and insert new loaded mag. If I slap the bolt catch/release it does not chamber a round, I have to manually rack the charging handle to chamber a round.

Does anyone know why my bolt isnt locking back far enough to chamber a round using the bolt release?

I am using a S&W Lower w/ RRA LPK, BravoCompany Upper/BCG/Charging handle, and DPMS Stock/buffer tube/spring.

Thanks for any help in advance.

-Tom

Try another mag. For what it's worth I've seen multiple brand new P-Mags that like to over-ride from an open bolt for some reason. (Sacrilege to the church of Magpul, I know.)

 

[xtry51]

Something is out of spec if the bolt isn't being held back enough.

 

[HollowPoints]

Something is out of spec if the bolt isn't being held back enough.

Any idea what part exactly would be out of spec? As far as I know everything I used is "mil-spec" for all that term is worth.

Also to answer the ammo question I have used everything from Federal 5.56 to Tulammo BrassMax .223 and everything inbetween, doesnt seem to care what ammo is in it. And like I said, I have tried all types of mags, 40/30/20 round GI mags and also PMAGs.

I will snap some pictures tonight to show you guys exactly what Im dealing with, maybe that will help. Ill try switching lowers as well.

 

[W.E.C]

try a different carrier ,if you have one.
if it happens every time with know good mags.

I had that problem with bolt over riding and not picking up the next round , not locking back every time sporadically,

and a change to a spikes tac. carrier solved it.

visually I could not see any difference in the bolt carriers.

but the function was the proof in the pudding.

( this doesn't mean this is YOUR malfuntion)

 

[SJan]

I would suspect the bolt catch itself. Did you buy or build the rifle? Does the catch move freely with only the springrresistance?
What if you lock the bolt back manually, insert loaded mag, then hit release

 

[HollowPoints]

I would suspect the bolt catch itself. Did you buy or build the rifle? Does the catch move freely with only the springrresistance?
What if you lock the bolt back manually, insert loaded mag, then hit release

This is a built rifle. The catch seems to move freely and works fine to lock the bolt back. Same thing happens if I lock it back manually and insert mag, slap catch, no chambering of round. It just seems the bolt carrier doesnt lock back far enough in the upper.

 

[warwickben]

Did you dry fire it with out a bolt in ? I know you can mess the bolt catch up .

 

[HollowPoints]

Did you dry fire it with out a bolt in ? I know you can mess the bolt catch up .

Never been dry fired. Ive had it apart many times and all the parts look identical to any other AR you would take apart.

 

[not new guy]

Is the bolt stop catching the face of the carrier or the bolt face? Got a picture? Maybe try removing the bolt hold open lever, make sure you have the right spring in there and nothing else is wonky and see if it still happens.

 

[Mr. Brownstone]

So, even when you pull the charging handle all the way back and push down on the bolt catch you have this problem.

When you put an empty magazine and pull back on the charging handle and it locks back, you have this problem.

But if you put a full mag in, pull the charging handle back, and release, it chambers a round.

When you fire the rifle, it cycles and chambers a round.

You say the catch locks the bolt back when pulled manually but it doesn't feed afterward Does it lock it back all the way? or same distance when mag catches it.

If the above is true, it rules out short stroking. I believe it also rules out Mags.

 

[not new guy]

My money's on bolt catch spring or plunger problems, or there being crap in the little space it sits in preventing it from coming all the way up.

 

[dyer01905]

Is the bcg made by the company we shall not speak of? (Ice Arms) or did you dry fire the lower without the upper on allowing the hammer to hit the front of the fcg pocket denting the metal by the bolt catch causing drag on the bolt catch?

 

[soam]

Tom,
When your bolt is locked back, does it look like this:

or like this:

Note that in the second picture the bolt catch is catching the carrier, and not the bolt. If you have a situation like the second picture, I suggest taking the buffer and spring out of the buffer tube and making sure everything looks correct. Are you using a carbine tube/spring/buffer, or rifle tube/spring/buffer?

 

[charlie88]

Had the same problem with my carbine setup(bought it built) it had the rifle length buffer spring in the buffer tube not allowing it to compress enough for the bcg to go all the way back. Get the shorter carbine spring and enjoy.

 

[HollowPoints]

Tom,
When your bolt is locked back, does it look like this:

or like this:

Note that in the second picture the bolt catch is catching the carrier, and not the bolt. If you have a situation like the second picture, I suggest taking the buffer and spring out of the buffer tube and making sure everything looks correct. Are you using a carbine tube/spring/buffer, or rifle tube/spring/buffer?

I was just about to reply with pics when I saw this. Ill still post them but my bolt looks like the second picture. I suppose I should take this buffer and spring out and swap it for another. I have a fixed Carbine style DPMS stock, maybe I need a rifle length buffer tube/ spring/ buffer? My rifle is a mid length setup.

 

[soam]

All that really matters is that all three parts match. If you have mismatched parts it can cause problems like this.

 

[soam]

Specifically I believe a rifle spring in a carbine tube can cause this problem, so I would make sure you have a carbine spring.

 

[SJan]

I have a fixed Carbine style DPMS stock, maybe I need a rifle length buffer tube/ spring/ buffer? My rifle is a mid length setup.

Rifle buffer is 3.765"
Carbine buffer is 3"

Rifle spring is 11 3/4 -minimum to 13 1/2"
Carbine spring is 10 1/16 - minimum to 11 1/4"

The next questions -Is your fixed carbine stock on an actual carbine receiver extension and pinned or is it on a rifle length receiver extension ? (some manufactures do this on fixed telestocks)

Rifle receiver extension is 9 5/8
Carbine receiver extension is 7 1/4 (commercial vs mil-spec will vary a bit)

 

[slugworth]

Nice work mlaboss..

Good info..

 

[HollowPoints]

Rifle buffer is 3.765"
Carbine buffer is 3"

Rifle spring is 11 3/4 -minimum to 13 1/2"
Carbine spring is 10 1/16 - minimum to 11 1/4"

The next questions -Is your fixed carbine stock on an actual carbine receiver extension and pinned or is it on a rifle length receiver extension ? (some manufactures do this on fixed telestocks)

Rifle receiver extension is 9 5/8
Carbine receiver extension is 7 1/4 (commercial vs mil-spec will vary a bit)

Spring is 11" on the button
Buffer is 3.5"
Buffer Tube (receiver ext.) is 7.25"



That's the stock and buffer tube setup.

Do I need to switch this setup?

 

[SJan]

Had to recheck the measurements, my carbine buffer is about 3 3/8.

It doesn't seem to you have a conflict of parts there

 

[HollowPoints]

Is there any possibility the buffer is hitting the back of the tube, not allowing me to pull the CH and Bolt back far enough to catch? Would a shorter buffer work?

 

[SJan]

You said your buffer is 3 1/2
I checked several carbine buffers I have, they are 3 1/4 or 3 3/8 at the most. That may be enough to cause a problem

It could be too long of a a screw holding the stock to the receiver extension.

I'll give you an extra carbine buffer if you want to try it

 

[soam]

Spring is 11" on the button
Buffer is 3.5"
Buffer Tube (receiver ext.) is 7.25"



That's the stock and buffer tube setup.

Do I need to switch this setup?

If it's not too far, I would suggest taking your rifle over to Precision Armament Werks in Franklin. They carry AR parts and will probably be able to help you figure out which part is the culprit and get you a suitable replacement. If I had to take a wild guess, I would look at the buffer. That whole setup looks unfamiliar to me though - it looks like it attaches to the receiver like a rifle tube, but it's carbine length.