AR Sponsor
Posted: 7/15/2005 10:34:11 PM EDT
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You know what I find funny is that most every part of an AR is swappable with most any other manufacturers parts. But every one keeps talking about parts being made to mil- spec. Think about what you are saying here. If you can take BBL from company A, and install it on company’s B, C, D, or E’s. upper assembly as well as all the other parts and pieces. Then what the hell is not to specification. Ok so Colt is the different story here. Lets see here though. What is different about Colt? Just a few parts and pins. All the important functioning parts, Bolt carrier and bolt as an example will fit into every other brand of upper out there. You read in here all the time that this is done by do it yourself AR builders. So if these important parts will work from one to another I say again what is out of spec? Or not to Mil-Spec. I wonder where Logic and reason go sometimes. I was a machinist many years ago. Do you all want to know why parts can be out of spec, so to speak. I will tell you. How long do you think a drill bit will last? The first hole you drill will be perfect. After the 50th hole guess what the bit is beginning to wear down. This means the hole it created is slightly smaller and not as deep as the first one it made. If you think that because the hardened steel of the drill bit will not wear out because you are drilling aluminum think again. There are other factors to consider as well. The machinist themselves just doing the work will differ. Do you feel that each part gets locked into the holding block or vise Exactly in the same location as the five thousandth one before it? Did the guy put the exact same amount of pressure on the clamp? Did a small flake of debris get in the vise and hold it off centre? The same goes for CNC machining. The automated stuff that we mortals do not even touch while the process happens. Maybe the air pressure dropped or raised throwing things off a hair. There are many other examples but that would make this read way to long. Truth is there are plus and minus tolerances in machine work and specs. That’s why every once in a while you get something that don’t fit quite right. Like trigger pins as an example. As a example this particular lower was the last one drilled before the bit was changed and the trigger holes were not 150.000 in diameter but 149.050 just a fraction small but still in tolerance. The pins were also the last ones to be made and the cutting tool that makes them was worn so instead of the pin being 150.000 in diameter they are 150.100 Therefore the pins are ok but to the larger end of the tolerance. They must be out of SPEC then right? Nope but you can bet they will fit but you will be pounding a bit harder than normal. Ask Mongo ARFCOM’S one and only Evil Machinist and respected person of knowledge if I am wrong. The AR is a precise piece of work no doubt. But they are not precision pieces of machinery with tolerances of + or - .000000000000001 If they were only Bill Gates and Donald Trump would be the owners of these weapons. Just my thoughts on Mil-Spec |
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what about lowers with raised rear shelfs? what about stocks not fitting on all tubes except on certain manu.? what about h sear block? what about big pivot pins? what about big trigger/hammer pins? what about all the guys that use that sales pitch?  just giving you a hard tim, there are slight tolerance/spec difference due to things you have stated and i agree! just like everything else in life.what i believe in is great qc process! |
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The fact that you devoted an entire post about MILSPEC to machining practices shows that you are maybe a tad unclear on the concept. The milspecs for AR based rifles all contain exactly one line devoted to machining and dimensions. That line says, and I am paraphrasing here, " All parts shall be made as per current drawing". That's it. The remaining dozen or so pages are all devoted to inspection and quality control. Some not-to-spec anecdotes: The upper receiver that came on my "stop sign" era SGW / Oly Arms rifle will not fit on any other lower I have tried. The takedown pin holes are misplaced. Now, that rifle works just fine as it came from Oly, and for years I didn't know there was an issue, but the fact is that interchangeability is zilch. I bought a selector at a gun show once, and when I tried to install it, it wouldn't go any further than about half way into the receiver. Inspection showed it was bent along the shaft. Closer inspection revealed that this was because of a quench crack that had occurred at the root of the "fire" cutout along the shaft. Both of these are issues of QC. In the case of the Oly upper, QC missed the poor hole placement, and the gun went out to a customer. In the case of the selector, the manufacturer's QC probably did catch the bad part, and rejected it. It then somehow ended up as a gun show special. Bottom line, I have two bad parts. No matter how reputable the company that made them, how perfect the raw materials, some stuff gets out that is bad, and if you buy stuff that is not coming from first line of a top tier contractor, you run a much higher chance of getting a bad part, because their QC is not up to the government contractor levels. How you want to proceed knowing this is up to you and your personal risk tolerance. Some people want only the best. Some people are willing to chance a bad part in the quest for a good deal. Either party may get an excellent rifle, either party may get a lemon. All they have done is swung the odds one way or the other. Decide which avenue you prefer, and go for it. I never understood why people on the internet get so worked up over other people's personal choices. |
| the term "mil-spec" when refering to a AR, is nothing but a sales pitch, and a way for them to justify a higer price, to fool people into believing that their rifle is made to the same standards as the M16 carried by the military.........the only thing mil-spec about a AR, is you have a USGI magazine |
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I’m new to ARs, so excuse this post if it seems obvious, but Why is it that so many ARs come with crappy 'out of spec' parts yet so many other platforms seem to be just fine? I hardly ever hear about an HK USP or SIG not working properly, or having some sort of malfunction. How about Remington 700 rifles...how many of those do you hear about having this problem or that problem? and the list goes on.... After doing a LOT of reading on the subject what I found is that Colt seems to be the best because they test all parts they subcontract to other makers and make sure they are within spec...where others like bushmaster or RR test a few out of a batch and that’s it (unacceptable IMO). I guess if the average Joe had the tools to test the parts then you could buy any rifle and test each part to see what was and was not in spec, send those parts back, and fix the rifle up yourself...all while getting the same quality of a Colt at a lower price. I just don’t understand how a company that makes a living off of selling a product could let sub par quality out the door...and especially when it may make its way into the hands of people who would potentially depend on this rifle to save their life. Why put up with sub par quality? |
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Wow - this is going to turn into a shitstorm. First off - technical speaking, there is no such thing as military spec AR15. The military does not use AR15's so there is no such thing as "mil-spec" for the AR platform. With that out of the way, I get the impression you are either trolling or have no idea what mil-spec means? (if I'm wrong I apologize ahead of time) The term mil-spec is thrown around a lot and is not always used they way it should be. Mil-spec means the part is made exactly to the specifications called for in the TDP that Colt and FN uses to build M16's\M4s. That does not mean the part has to be built to .00000x tolerance but it does have to be made to within the specified range. All parts\dimensions called for in the TDP have an acceptable tolerance range that the part needs to fall within. The fact that a barrel from company A can be installed on a Mil-spec upper does not mean the barrel is mil-spec. For a barrel to be considered truly mil-spec, the following must be true... Made from 4150 steel. Milled to the correct profile (varies depending on weapon (i.e. M16, M4, etc)) Fully Chrome lined bore and chamber 1/7 twist rate 5.56MM chamber High pressure load and MP tested Parkerized finish. Barrel threaded to 1/2x28 to accept FH forged front sight base with bayonet lug "M4" barrel extension (only for barrels designed for the M4) + probably some others that I missed\forgot about My point is, there are 1000's of barrels out there that you could install in a true M16 or M4 that would not have even one of those specifications and yet could potentially work just fine. Using your logic, they are "in-spec" but in reality they are not. |
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Physical dimensions (or form, fit and function) is only one component of what goes into military specifications (mil-spec). Other attributes include things like: materials certification testing Just because you can pound a pin into a hole to make it fit doesn't mean it fits the specifications. |
tag for reference 
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| I think alot of this mil-spec doesn't matter argument comes from people who are attempting to justify paying an extra thousand dollars for a Colt, and or people like "This is just like what the uber tactical SEAL Delta Ranger Recon ninja space shuttle door gunners use, I know that because thats what the SEAL at the gunshow said when he sold it to me, along with that bag of Beef Jerky".... |
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To me, Mil-spec means the rifle and it's componants are inspected and approved per military specifications before they're boxed and shipped to the troops. Doesn't matter what size they are or what specs their built to, so long as they're given a go/no-go by military needs and requirements. Not many manufacturers do that and Colt is the first one that comes to mind. I have a 6400 and a franken gun built on Oly, RRA, Bushmaster and Cavalry Arms parts. The franken gun works fine but the Colt is what I'd take with me into a situation. |
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Like most of us here, I've heard this argument over and over again. The way I see it is, I'm happy if my rifle is more or less as reliable, accurate and durable as the rifles the military buys and uses. If the USMC and US Army require chrome bores and chambers, I want them. If they call for a forged FSB, I want that. And if they expect lowers and uppers to fit well and not need a hammer and punch to disassemble, without a screwdriver, I expect the same. That being said, I believe Bushmaster, Rock River and several others make what are essentially a good quality M16-type rifle in "civilian form." I have a Bushmaster with a Government Profile 20-inch barrel and I know that it is the same weight and length and operates very much like what our troops are issued. I also have a 20-inch HBAR and I know it is heavier than what are troops carry and has a naked muzzle, with no flash hider. They are both accurate and reliable. If the military demands a part be hardened steel, I want it that way. If they insist that a part be chrome, I want my part chrome too. The assumption is, the Army and the Corps want it that way because it works better and/or doesn't break as often! Don't tell me about the "lowest bidder." We all know the military has the ability to request changes and improvements to everything from B1 bombers to M9 pistols, and they do it periodically. I think that's all most guys are looking for in trying to get a product that is "Mil-Spec!"  (Edited to fix typo) |
I know of a lot of pistol manufactures that put out crap. Some AR manufacturers pu out crap. What is so confusing or mystical aboout that? There is Lorcin and Davis, etc pistols. There are Hesse assualt rifles. How many companies produce Remington 700s? How many produce HK? Just one. If you want to look at multiple pistol manufactures its easy to see crap out there. Look at a Norinco 1911 and compare it to a Springfeild or Kimber. |
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I could care less if my AR15 is/isnt milspec. I'm not dragging it through hell. I'm taking it out to shoot at paper and cans, then it gets cleaned and put back. Colts' may cost more because (maybe) they put more money into their QC department. Thus more rifles get checked over before being shipped off...thus the Price of each rifle goes up. Maybe the tighter spec'ed ones go to the military. And looser spec' (but still within) go to civilians. Maybe others (RRA, BM, ect.) are cheaper because they dont check them ALL before shipping. They use the money they saved on having less QC tech's...and lower the cost of the end product. just my thoughts,  |
| MIL-R-45587A, MIL-R-63997B, and MIL-R-71135 are three applicable MIL-SPECs. They are all currently "inactive" according to http://assist.daps.dla.mil, as is MIL-C-70599A regarding the M4 and MIL-C-71186 on the M4A1. As stated earlier, the biggest part of the content of these (and all) MIL-SPECs is the QC requirements. When using ASSIST, it's best to choose the "Search By FSC" option-small arms of 30mm and below are in FSC 1005. |
Thanks for the links and #s. Those seem to cover complete weapons. I am looking for MIL-SPEC parts. Like a MIL-SPEC for Carrier, M16A2, Firing Pin, M16A2, etc. I will search that site and see if anything turns up, but I have not seen anything to suggest there is a MILSPEC for each M16 part. |
| Here we are allowed to use alot of different parts in our weapons, but there is one that is absolutely forbidden. I dont know what it is called in english- it is the pin that holds the firing pin in the bolt carrier. Because it is so small and easy to lost when you are cleaning the weapon some stores here started carrying plastic ones. That most definietly is no mil-spec, or whatever that means. For us it meant that it dont work, and messes up weapons, only you dont know till you need the gun... |
thats not a question if mil-spec, thats just a question of how smart   |
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To clear up a bit. My mind only thinks in black and white. I understand there are many specifications regarding the AR. The materials, chrome lining, dimensions and so on. By my own error I was addressing only one issue with dimensions. I see now that this was not as clear as I thought. As one reads in here the problems with parts fitting or not fitting seem to be common. More than anything I was not looking for debate but providing basic information for the layman. |
There are many people with varying problems in here that are always questioning about something not being to Mil-Spec. The most common read is something seems not to fit well. I was just attempting to point out to those members that may not understand why there parts may be too tight or too loose. |
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