Yesterday I received a stripped upper I'd purchased from a well-regarded manufacturer for an SPR-ish build. While inspecting the upper, I noticed a variance in receiver wall thickness. For a normal build I wouldn't be concerned but I'm trying to squeeze as much accuracy out of this thing as possible. Is this worth bringing to the attention of the manufacturer for an exchange?
Out of spec upper?
- Thread starter Thucydides
- Start date
Fuck, did I accidentally go to Reddit?
Stop mincing about, who's the manufacturer so that we might actually be able to help you instead of trying to decipher some circles on a photo.
Stop mincing about, who's the manufacturer so that we might actually be able to help you instead of trying to decipher some circles on a photo.
I’ve seen some uppers that were pretty off in different areas.
One of the things to look out for is the wall thickness under the ejection port door in the mag well orifice on the upper. Some that have been machined way off-center are paper-thin, to the point you can break that section with your fingers easily.
Others have the carrier raceway machined at an angle.
Others have rail dimensions out of spec (too wide vs too narrow, spacing incorrect).
Gas tube apertures too high/low, or not machined all the way through and a thin wall of aluminum left on the inside, obviously not run through dimensional adherence checks and Mil-Std gauging.
These are all pretty rare, but you’ll come across it now and then.
One of the things to look out for is the wall thickness under the ejection port door in the mag well orifice on the upper. Some that have been machined way off-center are paper-thin, to the point you can break that section with your fingers easily.
Others have the carrier raceway machined at an angle.
Others have rail dimensions out of spec (too wide vs too narrow, spacing incorrect).
Gas tube apertures too high/low, or not machined all the way through and a thin wall of aluminum left on the inside, obviously not run through dimensional adherence checks and Mil-Std gauging.
These are all pretty rare, but you’ll come across it now and then.
I'm not sure if what I'm seeing is what your concern is, but it looks like the charging handle slot isn't inline with the center axis of the bore of the upper. If that is the case, I would be checking clocking issues between the barrel extension and bolt lugs as the BCG goes into battery, as the BCG might be rotated the amount of the misalignment.
I am guessing that it i s a BCM.... I have seen several like that. And they are the worst when it comes to their broken ass shit. If it is them, you are better off throwing it away and buying from a good brand.
Good money it's Centurion. BCM doesn't do that index pin cut, but Centurion does in that manner. FCD/SOLGW have a hole for an indexing pin above the gas tube, but not like that.
Centurion...and it wouldn't be the first time with receiver parts out of spec. I know of some of their lowers with their FCG pins holes are way above spec.
Years ago I had one similar but I didn't catch it until it was assembled. Could only pull the charging handle back about 3/4 of it's normal travel. The BCG raceway was at an angle and the carrier would enter the buffer tube at an angle and bind up in the tube.
Do not use that upper IMO.
Do not use that upper IMO.
I bought a blem BCM upper receiver that was cockeyed like that, it was like when it was made they drilled it at an angle or something is the best way I can describe it. They sent me a new one.
I did not even ok at the pictures. Only upper that I have ever seen out of spec is BCM. And ithey were WAY out of spec.
I've updated the post with the areas circled that I'm measuring
Yes, left side upper wall (where charging handle/gas key would travel) is .03 thicker than right side. Again, I don't have any concerns regarding safety, just wondering if it would impact accuracy. Also, BCG moves freely and gas key lines up with the port.
Nightforce, Leupold, Sierra, Nosler, Hornady and Geissele sell blems through their own sites or retail outlets
To me it's more important if they actually stand behind their product or not
Unfortunately some companies have "haha fuck you" warranty policies
- Nov 3, 2010
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Don't necessarily agree. There are no altruists in business...just people who care enough to not have their rep damaged to where it will hurt sales and the bottom line. Kinda like a politician...once you get past a certain level, they're just out for themselves and you're too insignificant to matter.
Shit happens in production and always will. I don't begrudge selling a "blem" for less so long as defects are noted or it can be verified to be fully cosmetic. Better than trying to pass crap off on me and hoping I won't notice. And if we're being honest, the presence or absence of blems for sale isn't a true indicator of a deceptive practice either way.
I am not saying that nay company is altruistic. They all want to make money, some are willing to cut corners to make more. Some companies pride themselves on quality and do not sell blem parts. The companies that produce truly great quality parts don't sell blems.
Shit does happen in production. Companies can either scrap the mistakes or try and scrounge some money from people. It is all about QA/QC.
Have you ever notice that some companies seem to always have blems and others only have them once in a while? And some never have them?
THAT, I will give you, is sus. Geissele in particular when the HK super modular rails for the 416 is one they would do limited runs and have large "blem" sales of that item. Thus a high margin of blems on a particular product, but less so with their "regular" production line.
Yesterday's "Tier 1" is tomorrow's "Shit tier" (Hell damn near all of 'em are "mid-tier" anyways)
Said it long ago, I no longer have "good guy" lists....just groups of vendors and mfg's that have yet to fuck me over...
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Quoted to preserve retardation so future generations can see the effects of alcohol fetal syndrome.
So you must be a special kind of retard..........
I am guessing you just fan boi and do not actually know anything on the subject.
Not just that. It's a way to move higher volume without diluting your brand. You can also write off the difference to minimize tax burden. Finance guys understand this. It results in higher revenue and profit while decreasing taxes owed. Win, win, win. It's cheaper to keep a machine running spitting out parts than to shut it down. It results in higher ROI, even if you have to sell it at half the price. A machine not running is loosing money anyway you cut it.
There are reasons alot of products are sold as 'blems" without a flaw to them. I have entire guns build from "blem" parts that are indistinguishable from the same parts they sell as new / non blem other than markings. I mic and measure most critical dimensions out of habit and function test with known dimension parts like BCGs. Save the money and buy the blem. 99% of the time it's a cosmetic issue, if there is one.
Get yourself some tools to correct this. This first thing I would buy is a lapping tool. That should fix most issues.
Unless you have a lathe it's a waste of time and money. You aren't getting the RF square.
Or you can just buy an upper that is already true...because it's part of the manufactures acceptance procedures / qc.
I have been fixing and building AR uppers for over 20 years. It's not worth breaking out the fixtures unless it's the only option.
- Nov 3, 2010
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Is there anything you don’t do?
Exercising restraint, humility?
If the bolt race is correctly centered then you should have good alignment with the barrel. If the bolt is aligned with the barrel then locking lug engagement should be good. Throw a charging handle in it along with a bolt and see if there is any problems cycling the bolt. If not go for it.
On the other hand, if you paid good money for a product and you think there is a problem, then contact the manufacture and work things out.
On the other hand, if you paid good money for a product and you think there is a problem, then contact the manufacture and work things out.
