My 2 new FAXON 5.56 AR-15 barrels are (too) overgassed ... sigh

Surely ... this is not news to FAXON ... but I was blindsided. A very disappointing experience ... x2.

Life.

If only in their details/descriptions they included this information (and the required use of an adjustable gas block), I would/could have taken it into account while making my component/purchasing decisions ... and I would be making initial sights/optics decisions today.

I reeeeeeeally like these 2 Uppers that I have assembled (as well as the GreenMtn Upper, mentioned in the email text below) and look forward to having this situation resolved.

I will update after FAXON responds.


=======[ email that I sent to FAXON last night ]=======

@SUBJ: Overgassed? Issues with 2 of your Gunner barrels

Hello.

Recently I was bitten by the AR Building Bug (directly connected to deciding that it was time to enter the Free Floating Handguard World), something that I have successfully avoided for over a decade (my last two AR Builds were in 2004).

I ordered a new-mfr 1:12 M16-Profile pencil barrel (for some lighter-weight-bullet action) from Green Mountain, which I received a couple of weeks ago, and decided upon two 1:8 5.56 Faxon Gunner barrels.

You have no idea how much I have been looking forward to getting my two Faxon 5.56 Gunner barrels, a 20" from AR15Discounts and a 16" from Brownells.

As with the GreenMtn barreled-Upper a week ago, after checking headspace on both Faxon-barreled Uppers I attached them to Lowers (20" with an A2 rifle stock & 16" with an M4-style collapsible) and headed into the backyard for a quick testfire on each. I only had 7 rounds left in the open box of the SouthAfrican M193 that I use so I fired 4 in the 20" and 3 in the 16" ... collected & segregated the cases and return to the house to inspect them.

The 20" cases looked bad and the 16" cases looked HORRIBLE. The first thing that came to mind was unpolished chambers but I quickly discarded that thought as I thought it thru.

It appears obvious to me that with both rifles the bolt unlocked before the pressure dropped to release the cases from the chamber walls, creating what are apparently drag marks on the cases.

Is this what "overgassing" does? Causes an early unlock scenario and the extractor tries to DRAG the cases out?

Here are 2 pics, this first of the Faxon chamber markings on my barrels:



This 2nd pic shows 3 sets of fired cases. On the left are the 5 that I (test)fired in my GreenMtn rifle, in the middle, the 4 that I testfired in the 20" Faxon rifle and on the right, the 3 that I testfired in my 16" Faxon carbine.



BTW, it does not show in the pic but the "drag marks" are also on the case shoulders of the Faxon-fired cases.

Looking at those carbine cases (3 on the right) it crossed my mind that it was surprising to me that they managed to be extracted. Close inspection of the rims testified to the additional force exerted.

I carefully cleaned the rifles and went back out to test fire again. The cases produced by the 20" were more of the same. The 16" only managed a single shot and then failed to extract, ripping off a chunk of rim with the effort.

After thinking about it a bit, I cleaned the 16" again and mounted it on the A2 Lower to see if the heavier rifle buffer would make any difference. Nope. All I managed to do was get another FTEx with another chunk of rim ripped off (join me in prayers for the health of that extractor ).

---------------------------------------------

So ... it appears that I have invested over $300 in my two Faxon barrels (and hundreds of dollars on components to build up rifles around those specific barrels) that, as it turns out, are overgassed (one severely, so) and, therefore, require the additional purchase and installation specialty adjustable gas blocks in order to be able to even use them. <sigh>

Does that sound like a fair summary?

S'funny ... I was greatly intrigued by those Superlative(?) adjustable gas blocks that you have on your website. They appealed the my Geek Gene. But the thought of spending $180 on adjustable gas blocks for ~$300 worth of barrels, especially when I do not use them in a way the needs the gas blocks to be adjustable was a No Go.

Anyway ... my two new Faxon-barreled Uppers are safely tucked away in my north gunsafe until I can sort out this mess.

I would like to hear your thoughts and/or advice on my situation and the accuracy (or inaccuracy) of my assessment of what is happening with these barrels.

Thank you! I look forward to hearing from you!

someguy2800 said:

What are the port sizes on them and gas tube length?

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20" is rifle-length and 16", mid-length.

No idea regarding the port sizes ... until after I remove the GBs to install the AGBs.

Varminterror said:

Most barrels, in general, are generously gassed, if not overgassed. Personally, all of my AR's have AGB's, so I wouldn't have it any other way.

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If the barrels that you are selling are overgassed to the point where adjustable gas blocks are required for the firearm to properly function, you should include that tidbit in the listed Details about the barrels. All I'm saying ...

Prior to building these 3 I had 5 ARs all with non-adjustable gas blocks. They all run properly.

The one that I just put together around that GreenMtn barrel, with its non-adjustable gas block, runs properly.

LoonWulf said:

Not trying to give you static, but going forward use this as a learning experience.

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Hahaha ... everything is a learning experience.

While I was very disappointed yesterday, I am not upset with FAXON. I just think that, considering that they must be aware that these barrels are overgassed to the point of being unusable with regular gas blocks, they should inform their prospective customers. That doing so is just good business.

It could be due to something as simple as them only thinking in terms of AGBs and giving zero thought to regular GBs. That could result in a blindspot for them reflected in the complete lack of information on this point.

LoonWulf said:

Best to check stuff like gasport dia, and alingment BEFORE installing everything.

Click to expand...

Oh, all of my gas blocks are aligned with great care. Knowing the gas port diameter when I was putting these together would have told me nothing as I was unaware that a reputable barrel mfr would make the port too large.

One thing that I have often wondered ...

Why don't GB mfrs lightly scribe center-line marks on the rear of the GBs that could easily be lined-up on a like center-mark provided by barrel makers on their products. I think that it would make the whole "carefully lining up the gas block" process MUCH easier ... y'know?

LoonWulf said:

Again not giving you static, but knowing the port dia would have told you that they would be over gassed, or at least LIKELY to be over gassed.

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<chuckle> Well, DUH!

OT, sorta ...

That brings to mind the time that I built what I think of as my "carbine" FAL. Must have been about 15 years ago.

Since I cut several inches off of that barrel, I knew that I would have to open up that port for proper function.

I scoured the forums for expert port-size info. Somewhere I found a plausible report that it shouldn't be opened up more than sizeX but I realized the this fellow could not tell me a MAX for my rifle ... so the long cycle of disassemble/drill/reassemble and test, repeat ... began. It took a-while. WHEW! ... but Easy Does It finally paid off. IIRC, I ended up having to open that pup up to, like, sizeX+15% before the rifle performed reliably. It is one fine little rifle. The favorite of my FALs.

So I had to wander over to Fotki to see if I had a pic stored:

MistWolf said:

The Faxon barrels delivering good precision are the match barrels ordered with matched bolts.

GB, contact Black River Tactical and ask them about their Custom Tune Micro Port.

http://www.blackrivertactical.com/concrete5/customtune-gas-port/
View attachment 796245

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Thanks, MistWolf, but I will be happy with what I consider "decent" accuracy; ~MOA.

I already have a pair of adjustable Wojteks inbound. I think that there is a very good chance that each of them, after initial setup & optimization, will never be adjusted again.

If I had rifle(s) on which I was planning to tweak the gas often, I would probably buy one of the Superlatives. For a gas block with port-size options, the BRTs look look very nice. Thanks for the link ... I have added it to my Bookmarks.

I quickly perused the BRT page and it looks to me like one of those gas blocks along with a set of different-size port plugs (assuming that they have designed them to be user-changeable) would be a very nice way to go on a rifle that you probably won't often change but want to be prepared for feeding changes, periodically, down the road.

If your gas block is forward of the FFHandguard, it seems to me that it would be easy to pop off the GB, change the port plug and reinstall. You'd probably want to fit the GB a couple of mm forward of the ridge behind the journal so the you could more easily POP the GB loose from the accumulated carbon. Just thinking aloud ...