a thread on DPMS barrels sparked the question: why does DPMS produce such inconsistently chambered barrels?
expand upon that, why is any un-true 556 barrel un-true? in other words, what about the manufacturing process is flawed? why are so many low-tier manufacturers’ barrels not true 556 when labeled and advertised as such?
a couple of possible answers come to mind, knowing what i do know about machining and manufacturing-
do these manufacturers ream their chambers thinking a tighter chamber will compensate for other manufacturing deficiencies? i.e., increase chamber pressure in the hopes of increasing operation reliability, etc?
are they using worn out reamers? i assume these tools are tungsten-carbide-ish and can’t be resharpened or used past their effective life, so this doesn’t seem likely.
cheap reamers from less respectable toolmakers, producing inconsistent results?
are shop machining tollerances so loose that they simple “err on the side of caution” and shoot for tight?
I have a feeling that it stems from the common misconception that 5.56 NATO is .223 Rem, and the manufacturers that produce mislabeled guns are betting that their primary users will simply bimble into the nearest wallyworld and pick up a box of the cheapest .223 they can find for their next year of shooting. This also explains the oversized gas ports found on many civilian marketed ARs.
since the oversized gas ports are for the cheapest, lowest pressure .223 ammo on the shelves @ wally-world (Wolf)…how come they ship a gun with a chamber so tight that Wolf cases stick and rims tear with staggering regularity?
Wow, that would be a really tight chamber, and I would assume that if this is happening “with staggering regularity” that there would be a serious fault at play and numerous threads on it. As it is, I don’t shoot Wolf, nor do any of the people I shoot with, so all I know about Wolf is what comes in here. Because of my aversion to steel cased ammo, I inflicted my thought process onto the buyer, figuring that they would at least buy PMC.
I just noticed that “inconsistently chambered” was mentioned in the original post. On that matter I have no idea other than poor workmanship and poor quality control.
“staggering regularity” was hyperbole. i meant that stuck wolf cases seem to happen far more often with certain brands (bushmaster, dpms) than with others
i shoot wolf sometimes, especially with movement drills. however i only shoot wolf thru one AR (LMT upper…eats it fine). the rest of my ARs only see brass. i don’t like shooting wolf either, but i feel like its worth it sometimes. i just try to contain the cat piss smell to one rifle
if that’s true, why not simply label them 223 and chamber them 223? i might be giving the average AR enthusiest too much credit, but i would imagine that people looking for 556 specifically do know the difference, and will notice the difference in the form of headspace gages, stuck cases and the occasional kaboom, etc.
i dont see any benefit from deliberately mislabeling/misadvertising a barrel- not saying you’re wrong, just kind of hoping so.
on the other hand, which is worse? lying about your product, or having such shitty machining practices that your product lies for you?
it seems like the biggest issue is inconsistency. using DPMS as the example again, seems like a crap shoot as to what your chamber will look like- a lot of guys report true 556 chambers, most report tight chambers, and a smattering of too tight and too loose (unshootable) to boot. i’ve seen a few examples of the randomness myself, and many more here.
i’m guessing its basically poor workmanship, but interested in what part of the workmanship could be so poor. having a lead machinist for a father, i know quality tools and proper setup should give consistent machining results. everything is CNC these days- the programmer sets up the machine, and operator makes sure the machine and tool are operating correctly during a run, places and changes the part, and the leads (generally also the programmers) batch test the parts as they come out on the carts… it’s very simple, especially for something like chamber reaming. i just dont know how so many could fuck it up so bad.
sharp tools
proper setup
batch test the parts
it’s that simple to produce consistently in-spec parts.
You are giving the average enthusiast too much credit. When you can have arguments with gun store owners and supposed gunsmiths about the difference between 5.56&.223 how can you expect the general public to be any better. And yes I have had arguments with both in the last year. :rolleyes:
it’s too bad any resident barrel makers are too busy making barrels to chime in on this thread.
ETA: but these guys who dont think there’s a difference between 223 and 556 are exactly who i’m not talking about, though- they won’t NOT buy a barrel because it’s marked 223
Unfortunately, they have no real incentive to improve their methods or QC since they sell every barrel they make anyway. That’s the sad part of this story.
Here’s my thoughts on the matter. By marking a barrel 5.56 you have essentially bamboozled the less educated AR buyers out there who think they are getting something they’re not. That will allow you to potentially compete with companies like Colt, LMT, Noveske, Daniel Defense and the few others who turn out a good product. Then factor in gun store owners and sales people who know Jack Shit about AR’s and it’s easy to see.
Another thing to consider is how many people who have purchased an Oly Arms, DPMS, or Bushy upon learning that they didn’t get what they thought they were getting have then contacted the manufacturer to complain or ask for a refund?. Probably less than 1%. Most just end up buying a new bolt and/ or barrel and fix it themselves. So why make your stuff the right way the first time when your consumer base doesn’t know better or is indifferent?
I’ll take a stab in the dark and say that Bushmaster, Oly, DPMS, and the other poor performers make more money in the long run than Colt and the others simply because they crank out quantity, rather than quality and the money that they save in not HP/ MPI testing their stuff, not staking their castle nuts and carrier keys just adds up to more profit.
DPMS doesn’t do a lot of things correctly. Just this week I had to turn down about an inch of barrel to .850" so that a KAC RIS rail would fit on a DPMS M4 profile barrel. The area just behind the gas block was .936".
It was another case of “Just as good”…
I’m wondering if the issue lies in the chrome plating of the bore and chamber.
There are differences in 5.56 NATO, and .223 Rem. to be sure, but the major difference is the length of the throat. The actual chamber size shouldn’t be an issue with either cartridge. (Unless the chrome is taking up .002 per side.)
Wolf ammo has some kind of coating, hence the gunk and smell. Steel doesn’t contract the same as brass either, so chrome, gunk, and steel cases could combine to cause problems.
I guess the thing to do would be to do a chamber cast of the “tight” chamber, and get some accurate measurements. Compare these dimensions with what is stamped on the barrel. This would go a long way to eliminate speculation.
Good question. First, manufacturers always use “556 NATO” as a marketing tool on barrels. Remember that a lot of “manufacturers” don’t ACTUALLY make their barrels in house (read no control). DPMS most likely buys barrels from several sources.
I typically find barrels that are marked 556 NATO having everything from a 556 chamber to a 223 to something inbetween (that has no name). The “in between” chambering is the most common IMHO. How can I tell you ask? I have reamed a true 223 chamber with a 556 reamer and seen the amount of material removed. I have reamed an “in between” chamber and seen the amount of material removed.
So why don’t more companies use a true 556 NATO chamber? The reason is simple. Manufacturers do NOT want their customers calling them up and saying that their gun shoot 4MOA at 100yds (and want to return it)! These manufacturers are also assuming that their customers are most likely NEVER going to shoot true 556 NATO ammo and they are also NOT going to shoot it very much. Both of these statements are generally true (which is kind of sad) and is why we do not see more complaints about blown primers and stuck casings.
Not really. The chamber and bore are produced slightly oversized and then chrome-lined (or at least as I was informed by Dean Caputo).
There are differences in 5.56 NATO, and .223 Rem. to be sure, but the major difference is the length of the throat. The actual chamber size shouldn’t be an issue with either cartridge. (Unless the chrome is taking up .002 per side.)
The throat and free-bore are critical dimensions though. It is rarely an issue of the chamber body being too tight, but rather the throat (and headspace) that cause the most problems. As pointed out it really isn’t that the .223 Rem chambers are tight, it is that they are .223 Rem chambers in lieu of 5.56 Nato chambers that run much better on the ammo most guys here are using for the rate of fire required. The Wylde and Noveske chambers seem to be very good compromises in terms of reliability and precision by having chambers with just the right amount of free bore.
Wolf ammo has some kind of coating, hence the gunk and smell. Steel doesn’t contract the same as brass either, so chrome, gunk, and steel cases could combine to cause problems.
It also doesn’t expand and obturate the same way a brass case will, which is why a lot of crud gets pushed past the case neck, causing other problems.
I guess the thing to do would be to do a chamber cast of the “tight” chamber, and get some accurate measurements. Compare these dimensions with what is stamped on the barrel. This would go a long way to eliminate speculation.
The easiest thing to do would be to just buy one of Ned Christiansen’s 5.56 reamers and check all your chambers (except Noveske, Wylde, or dedicated anti-varmint rigs) by inserting it into the chamber area and turning it until it bottoms out. If there are metal shavings, you didn’t have a true 5.56 chamber ;).
Shooting steel ammo is not the problem (as long as you clean). The Lacquer on the Wolf cases does not come off (FYI).
The biggest issue seen is when people shoot steel cased ammo (do not clean well) and then go to brass ammo. Since the brass does expand, you tend to get stuck casings and or blown primers.
Assuming the plater has COMPLETE control, all the time, it shouldn’t be an issue. Things just don’t always work out.
I’m amazed at the speculation on this forum, of all places. Chamber dimensions have to be taken in these cases, otherwise it’s anyone’s guess, including mine.
How can you ream a plated chamber? That would leave steel and plating on the same surface. If you notice, chrome plating goes out the breech and muzzle so there isn’t a chance of the plating flaking.
The magic has to end somewhere.
as far as reaming a plated chamber, it’s done. i’ve never done it, but a lot of guys here do it in the course of employment. iraqgunz, for one, has reamed a few hundred bushmaster chambers. would you rather have a dangerous/failure-inducing chamber, or one with plating milled away? brass isn’t going to kick the shit out of CMV steel.
i dont yet know enough about barrel manufacturing to comment on whether or not it can flake. i do know that barrel chroming is a different process than, say, bumper chrome. it wears through. ever seen a shot-through chrome-lined bore?
