AR-15 extraction problem

[fireguyty]

Guys,
I just built a 9" AR-15 in 300 AAC Blk. I took it out the first time to shoot, and was having extraction problems. It would double feed if I had multiple rounds in the mag, and if I only had one in the mag it would fire and then lock, but the brass was still in the chamber. Its not stuck, all I have to do is tilt it back and the brass falls out. It was doing this about half the time. Because of the bolt locking, I don't think it is short stroking. Neither does it feel like it is over gassed.

This is about the 10th AR build for me and my first real issue. I am not an expert with AR's but not new either and this is my first 300 Blk.

Rifle:
9" 1-8" twist Delta Company 300 AAC blackout
Bushmaster 5.56 Bolt carrier group from another functioning rifle (I suspect this)
Pistol length standard gas system with standard gas block
Sun Devil upper and lower
DPMS lower parts kit
Carbine buffer and tube
Giessele (sp?) DMR high-speed trigger

Ammo recipe I got from Hogdon's web page:
BachelorJack's prepped LC brass
135 SMK
17.8 H110
2.120 OAL
CCI 400

I am thinking its a headspace (which honestly I know little about) or bolt extractor issue. So I have taken out the BCG and am gonna try another 223 BCG. The one I was using functioned perfectly in another rifle last firing. Also I cleaned the barrel real well.

Any ideas would be much appreciated.

Ty

 

[johnson]

Re: AR-15 extraction problem

Have you checked the extractor for tension? Does it have any o-rings or inserts?

 

[fireguyty]

Re: AR-15 extraction problem

Yeah, extractor has tension.

I'm not sure what o-rings or inserts you are referring to. The gas rings are perfect, and I have not disassembled the extractor because it feels great. Could you provide more information about what you are talking about here.

I'm gonna use another complete BCG tomorrow to rule out that.

Thanks, and keep em coming.

 

[BBJones13]

Re: AR-15 extraction problem

How many rounds on that bolt? You should not be swapping used bolts to new barrels. If only a few rounds on it, not a problem.

I would try a new bolt & try it with different mag/s. From your initial description, I would guess overgassed, but I think you might be right about the bolt. If you have access to heavier buffers and springs, I might try that after mags and bolt.

Not experienced with 300 BLK, so not sure if there are unique problems in this configuration.

 

[Scottmilk9]

Re: AR-15 extraction problem

the rubber o-ring in my opinion is a gimmick. Either you need a new extractor, extractor spring or your chamber needs polishing.

I built a gun recently and wouldn't extract, the claw part of the extractor was missing on a brand new bolt, so just give it a once over before doing anything extreme.

It is possible that its over gassed and riding over the extractor, but like you already mentioned, put a known good bolt in first.

 

[KevinB-KAC]

Re: AR-15 extraction problem

O rings and D-Fender are not 'gimicks' as they do increase extractor tension -- the question is whether a semi-auto gun needs those...

It does sound like you an issue with your extractor -- be it tension, design etc.

 

[gunslotreaper308]

Re: AR-15 extraction problem

could be a $5 fix...
http://www.bravocompanyusa.com/BCM-Extra...g%20upgrade.htm

 

[fireguyty]

Re: AR-15 extraction problem

Sounds like most of you guys feel its a bolt issue. Although this one feels fine, I have two other complete bolt carriers with bolts that I'll try tomorrow.

I appreciate all the suggestions, and I'll keep ya'll posted.

Scott, I'll be seeing you Saturday!

 

[Scottmilk9]

Re: AR-15 extraction problem

Kevin, it was my opinion, I guess I could have said the thousands of AR's I have built never needed one, but I make(have made for me) a heavy duty extractor spring.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KevinB-KAC</div><div class="ubbcode-body">O rings and D-Fender are not 'gimicks' as they do increase extractor tension -- the question is whether a semi-auto gun needs those...

It does sound like you an issue with your extractor -- be it tension, design etc.

</div></div>

 

[Ballista One]

Re: AR-15 extraction problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KevinB-KAC</div><div class="ubbcode-body">O rings and D-Fender are not 'gimicks' as they do increase extractor tension -- the question is whether a semi-auto gun needs those...

It does sound like you an issue with your extractor -- be it tension, design etc.</div></div>

They may increase extractor tension but are completely unnecessary with the proper extractor spring.

While the Bushmaster bolt group is certainly suspect, I wouldn't overlook the chamber. Who is Delta Company? Did they manufacture the barrel or are they re-selling another brand?

 

[308sako]

Re: AR-15 extraction problem

If you are firing at Desert Sportmans I will be on range #5 and #3 tomorrow AM,

gold Trailblazer.

 

[r1rn04]

Re: AR-15 extraction problem

check the gas port to block for proper orientation, found one on a model 1 sales kit that was out half the diameter of the gas hole.

 

[fireguyty]

Re: AR-15 extraction problem

Guys,
I took out a different BCG with a bolt that I had just rebuilt. Problem solved. I guess I didn't think the extractor was the issue because it was spitting 223 out perfectly a week ago.

I guess when your gun isn't extracting, check your extractor......duh.


Thanks for your time,
Ty

 

[rsilvers]

Re: AR-15 extraction problem

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: m_gale</div><div class="ubbcode-body">They may increase extractor tension but are completely unnecessary with the proper extractor spring. </div></div>

The O-ring is the best solution because the only extractor springs which are not overstressed do not have enough force. The O-ring, in effect, acts as a larger diameter spring - one which would not fit if it were metal.

I know because I bought every spring that Brownell's sells and modeled them all in $600 spring design software. Most of them were scary and the software issued all sorts of warnings - except for the original M16 design.

 

[USACS]

Re: AR-15 extraction problem

I would assume that the double-feeds involved 1 fired case and 1 unfired cartridge then?

If it were two unfired cartridges, then it would also indicate bad mags; though it looks like you have the issue solved.

I would also echo what everyone has said regarding a 5-coil heavier extractor spring. Tactical Springs sells theirs on their website or through BCM and a few other places. Well worth the minimal cost. I run them on heavily over-gassed SBR ARs with no extraction problems.