PDA

View Full Version : Define "Mil-spec" BCG....


missiontrails
05-01-2009, 5:17 PM
I have an upper on the way, and the BCG is not described as Semi or Auto, it simply states that it is a Mil-Spec MP BCG. I don't think "Mil-spec" could mean "semi", could it?

jeffyboy
05-01-2009, 5:23 PM
Here is the best write-up I have seen to date:

http://www.ar15armory.com/forums/Mil-Spec-t557.html

Fjold
05-01-2009, 6:15 PM
Mil Spec means - Made to the "minimum government standard". Which I also think is strange, how can anyone make "milspec" parts for parts that the US Government doesn't have a standard for.

entoxica
05-01-2009, 6:28 PM
"Mil-spec" today is a garbage term and cannot be used to accurately gauge or discern anything from a product. It has been applied to anything made in China that is camo patterned all the way up to meticulously crafted objects build to the exact specifications of the U.S government.

dchang0
05-01-2009, 6:34 PM
There's a standard--it's just not published for us to see.

missiontrails
05-01-2009, 8:35 PM
My question is, is there such thing as a "Mil-Spec" semi-auto BCG? I don't think the military is going to order SA BCG's.

evan69
05-01-2009, 8:39 PM
I would imagine that they meant "Mil-Spec" when describing the quality of the metal, and not whether or not is was SA or FA.

"Mil-Spec" seems like more of a marketing term anyway, correct me if I'm wrong.

maxicon
05-02-2009, 8:29 AM
In a nutshell:

Mil spec means:
MPI AFTER HPT
black extractor insert
5 coil extra power extractor spring
black o-ring
MPI = magnetic particle inspection, aka magnaflux
HPT = high pressure test. This is where they fire a proof load cartridge thats ~70k PSI.

How much any of this guarantees quality is another question, but the military specification for AR style bolts is clearly defined. Here are some of the references:
Drawing 12972700
MIL-W-63150
MIL-W-13855
MIL-C-71186
MIL-STD-109
MIL-STD-1949
MIL-STD-45662


Here's a huge thread where this is discussed extensively:
http://www.ar15.com/forums/topic.html?b=3&f=118&t=413742

Timmay
05-02-2009, 11:26 AM
Mil Spec means - Made to the minimum government standard". Which I also think is strange, how can anyone make "milspec" parts for parts that the US Government doesn't have a standard for.

"Mil-spec" today is a garbage term and cannot be used to accurately gauge or discern anything from a product. It has been applied to anything made in China that is camo patterned all the way up to meticulously crafted objects build to the exact specifications of the U.S government.

Mil Spec doesn't always mean minimum. It's the minimum of quality that can be accepted. The lowest bidder doesn't always get the contract if they can't meet the minimum requirements for that particular contract. I speak from experience. I am a contractor and work for USN/USMC aviation contracts. Trust me your money is being wisely spent....:smilielol5:

But with that said. A recent contract that went back up for bid was won by a company that over bid the cost for the Marine Corps. They still won it even though a few other companies had lower overhead costs. It was just that those other companies couldn't meet the "mil spec" requirements to land the contract so it went to the company that was essentially charging more but could meet the minimum requirements. So on a scale of 0-100 (100 being top notch) the bar could be set at 90 for all you know. mil spec BCG (at least in terms of the metal used in construction) could be made of a lot worse quality than "mil spec" and I am sure some here have owned one of those piece of craps. My point is if you go mil spec, or at least something close. You know your going to get something that is of at least respectable quality, and will work well. Some one can produce a BCG above those mil spec standards easily but at what cost and at what end result? I have a few BCGs that are mil spec and have yet to disappoint.

Josh3239
05-02-2009, 12:11 PM
Only difference between the semi carrier and the auto carrier is a small bit of metal.

aplinker
05-02-2009, 7:55 PM
It only has meaning if they actually define what they mean by mil-spec. I'd be much more interested to know what they use and how they inspect it than simply to say it's mil-spec.

Generally the term mil-spec means solely that the dimensions are consistent with real mil-spec items.

RECCE556
05-02-2009, 10:12 PM
Most companies don't build to MILSPEC because quite simply, they don't have to and it's cheaper for them not to. Now the common question is "if my stuff isn't MILSPEC tested, is it going to blow up on me?" The short answer is "not necessarily" but what's nice about TRUE MILSPEC stuff is they are AT LEAST tested to a minimum standard. Commercial companies don't have to follow MILSPEC and in nearly all cases, they don't. So you could get a BCG made from inferior metals (not just the raw metal alloy, but the quality of the metal bar they start with), you will most definitely get a BCG that isn't tested to MIL standards once they're machined (as Maxicon listed) and most companies don't even stake the keys to MILSPEC (CMT/Stag, RRA, Bushmaster, DPMS, CMMG, etc.)

So you have two things that are established...1) they don't test to "minimum" MIL standards and 2) they don't stake their keys correctly. Now ask yourself this, WHAT ELSE ARE THEY CUTTING CORNERS ON?

Also be wary of "contractors" who build for MIL companies. Just because they once subcontracted (or still do) for one of the actual TDP holding companies...subcontractor status does NOT mean that their own branded stuff is just as good. Case in point, CMT and LMT. CMT/Stag, most people know their stuff isn't so good. LMT though, surprisingly, has put some serious lemons in my experience. From re-drilled lower (through the anodizing and they ovaled out the holes) to bolts that wouldn't fit.

Now think about that. I had several bolts that would not fit into ANY barrel extension I had including real deal MIL barrels. That made me wonder...LMT claims to HPT/MPI each and every bolt like Colt does but how could they have HPT'd the bolt if it wouldn't even fit into a barrel extension? (Unless they're testing the bolts w/o using a typical barrel extension) So that made me think that if they didn't HPT this bolt, did they even bother MPI'ing it? Or shot peening it?

Another LMT issue I had. Several carriers came in when I fired them, they all kept eating up gas rings. I tried different gas rings AND different (Colt) bolts in the LMT carriers. Same issue. I sent them back to LMT and they told me (get this) that they were "NOT LMT CARRIERS"...mind you, I received these directly from LMT. The best part was that they were going to do me a "favor" and replace them with "legitimate" LMT carriers.:rolleyes:

Now over the years, I've gone through literally HUNDREDS of Colt bolt carriers. From the least desirable Semi-Auto, Unshrouded ones to the highly desirable "Full-Auto" ones (full circle, shrouded firing pin). NOT ONE SINGLE ONE EVER FAILED. Things like THIS is the reason why I pick Colt parts. I have also had good results with BCM's BCG's (including GTS's Ion Bonded/HPT/MPI'd BCM BCG's) and at this point, those are the only two I really trust.

Of course, YMMV...hell, you might have a Vulcan (Spechul Phorces don't ya know!?) BCG that runs like the proverbial sewing machine...I doubt it, but you never know....stranger things have happened... :)