Diagnose AR Malfunction

[Coronach]

well, there seems to be some disagreement about what the spec really is. (imagine that)

Huh. OK. Well, before we(I) lambaste BravoCo any more than we(I) have, we should probably try to find out what spec really is. If they're within it, then that's good. I hope they're within it, because I'd actually rather have a problem here than lose faith in a vendor...BravoCo has been good to me in the past. Besides, this would seem to be an imminently fixable problem, even if the easy answer (out of spec buffer spring) isn't right. Also, anyone can sell a lemon...it was just looking like they were selling a bunch of lemons there for a second.

Anyone have access to a technical manual for the M16 and the M4? I have one, somewhere, 300 miles west of me.

Mike

 

[SCBradley]

Both of my Bravo Co. carbine springs are 11 3/4" long, while my rifle spring (also from BCM) measures 12 3/4".

Because of this thread I decided to open the Magpul milspec CTR I got in the mail today. The spring that it came with is 10 1/2" long.

 

[taliv]

this was the answer i got back from bravo

The silvery color is the rifle spring (the others are carbine).
To confirm, count the actual coils in the spring (not the length).
The rifle springs have more coils than the carbine.
Thanks,

How many coils?

I just counted all of them and the silvery one has 44 and the others each have 37

Is there a chance you put the carbine spring in your rifle?


bradley, interesting. when did you order?

 

[ny32182]

This is the demo pic I took a while back, but unfortunately I can't remember if these are Bushmaster or LMT parts in the pic.



I can take a pic of known LMT factory parts if desired. I believe everything they make is milspec (stated, anyway).

 

[Coronach]

Hmm. The differences in spring length are a lot more dramatic in that picture than they are between my four springs.

Is there a chance you put the carbine spring in your rifle?

If the silvery one is the rifle spring, then yes. I put the longer, yellowish one in. So, yeah, this might be a case of running a carbine spring in a rifle buffer.

I still wonder why the carbine springs are longer than the rifle springs, when they're apparently not supposed to be, but hey. If switching the two will fix the problem, I ain't complainin'.

Mike

 

[ny32182]

I have never tried the wrong spring in the wrong buffer tube, but I have heard it can cause the kind of problem you are talking about... if there is a possibility that could have happened it would certainly be the first thing I would check.

 

[ny32182]

I would think a carbine spring in a rifle buffer tube would result in noticeably less effort than normal needed to retract the charging handle as well.

 

[Coronach]

Cycling effort seemed to be the same, but I wasn't comparing them side by side. I'm going to run by Gander Mountain later today, I'll see if they have a rifle buffer spring. Heck, it's a wear item. I'll eventually need an extra one.

Mike

 

[SHvar]

My carbine has a spring with 43 coils, and an LMT Heavy buffer. Of course if you compare it to the picture posted above with both springs and buffers, mine matches the longer rifle spring.
Depends how you count the coils, I dont call the last one a complete coil, so maybe its 44.
Of course the original rifle had a solid stock, but the original owner switched to a collapsable stock.

 

[carbine85]

You said it was a new bolt & carrier and a well used upper correct?
Have you check to see if the the carrier moves properly and smoothly?
Does the bolt move smoothly within the carrier and is the carrier key secured and staked?
Does the buffer move in the tube smoothly?
Do the mags actually fit up into the receiver properly?
Try removing the bolt catch and see if it's interferring in anyway.
Try applying pressure to the bottom of the mag and then release the carier.
Also, do this with dummy rounds. I have about 20 that I use for testing.

 

[Coronach]

You said it was a new bolt & carrier and a well used upper correct?

Yes.

Have you check to see if the the carrier moves properly and smoothly?

Yes.

Does the bolt move smoothly within the carrier and is the carrier key secured and staked?

Yes.

Does the buffer move in the tube smoothly?

Yes

Do the mags actually fit up into the receiver properly?

Yes.

Try removing the bolt catch and see if it's interferring in anyway.

It's not.

Try applying pressure to the bottom of the mag and then release the carier.

No change.

Also, do this with dummy rounds. I have about 20 that I use for testing.

Mine are at home.

Seriously? I'm back to the original idea. Car spring in a rifle buffer tube. It fits with the data, and it explains the phenomenon. It also has the benefit of being a simple check, once I get a rifle spring.

I went out again today with a well lubed BCG. No change. And Gander Mountain once again proved their uselessness by having their sales drones look at me blankly. "Gosh. I don't think we carry any gun parts."

"You have a gunsmith. Doesn't he have any parts?"

"I don't know. I just work at the counter."

"Ok. Is the gunsmith in?"

"No."

"OK. When will he be in?"

"I don't know."



Mike

 

[Evil Monkey]

my goodness, carbine spring, rifle spring, like 5+ different buffers, etc.

I wish Eugene Stoner was still alive .

I'd call him and say, "stoner?"

ES: yes, hello?

me: *** dude, why?

ES: I...I don't know man. I wasn't thinking.

LOL

Seriously though, I have put together a bushy carbine lower with a 16" mid length upper. I don't know the buffer weight and the spring is about 11" long with about 35 coils. Is this the right setup for a 16" mid length? I haven't shot it yet to see if everything's alright but function checking shows I may be good to go.

 

[SCBradley]

taliv said:
bradley, interesting. when did you order?

All were purchased separately from BCM with matching buffers between 1 year and 4 months ago.

Originally Posted by bravoco
The silvery color is the rifle spring (the others are carbine).

My rifle spring is copper colored and looks like the ISMI chrome silicon spring from Magpul (except for the length). My carbine springs are silver.

 

[Walkalong]

I just measured the spring I took out of my RRA A2 stock using a rifle buffer I removed from my RRA Carbine. It is 12 3/4" long and 40 or 41 coils. I am not sure how to count them.

The spring that came with my M4SOCOM stock (short) is 11 3/4" long and 36 or 37 coils.

 

[dc.fireman]

Coronach -

Hi. This is my first post here guys, but that's because this is a thread about a disease I have - BRD.

I have had a similar experience, using ammunition from a (at one time anyhow) reputable loader.

I have an RRA, and a custom built (by me) AR. Both have M4 feed ramps. What was happening to me, was that the primers were dropping out of the backs of the fired casings, before ejection.

Because the newer models use the M4 style feed ramps, they are longer and deeper - primers were actually getting stuck in the feedramps, which prevented full lockup of the bolt. There was enough of the primer sticking up into the breech area, that it was catching the rim of the incoming round, preventing it from being seated properly, and leaving a telltale 1/4" to 3/8" gap. I was able to use a very small long tipped needlenose pliers to remove the primers from the feedramps, and fixed the problem. I have since stopped using this ammo, as when I went to the next gun show and explained the problem to the ammo guy, he rolled his eyes, and handed me a bag of fifty rounds, telling me" yeah yeah, we're aware of that problem."

Hope it helps. Just something else to consider before replacing what may be a perfectly good spring.

-tc

 

[taliv]

dc.fireman, i've seen that happen fairly frequently with the primer landing in the barrel extension just forward of the bolt lugs, but never heard of the primer getting stuck in the actual feed ramp.

 

[KW]

My RRA carbine spring is 37 coils 11", and my Bushmaster rifle spring is 12 3/4" 43 coils. Do you have another stock/buffer/spring combo that you know works that you could swap on real quick to test with? Or possibly take this combo and throw it on a working rifle? That might help you determine what the real problem is before you start buying parts.