milspec/commercial tube?

Its like a Vampire rendition of Romeo and Juliet in here...

To stake or not to stake....that is the question...

Or maybe it was deciding if I wanted to goto the Keg or an Oyster bar...

To steak or not to steak..........

That being said, I have not the proper tools nor the proper knowledge being an AR noobie. I'll check that it is tight, see if it is staked or not...but yah, keep on staking in the free world.
 
Lower Reciever Extension Differences

Mmattockx,

My apologies if I misread the tone of your post, I assumed (obviously incorrectly) that you were just responding to my earlier comments.

The original "milspec" lower receiver extension (commonly, but incorrectly, called a "tube" or "buffer tube" but hereafter referred to as a LRE) was forged from 7075 alumium. The threads are then cut in the end of the "tube", and the rest of the "tube" is turned to its outer diameter of 1.14".

The "commercial" LRE is extruded from 6061 aluminium, and is made with an outer diameter of 1.17" with the threads then cut into it.

Why the differences? The original LRE had a fixed inner diameter due to the diameter of the buffer, spring and BCG. However, it is expensive and somewhat difficult to manufacture. In order to produce a cheaper version, the "commercial" LRE was developed, but because the inner diameter had to remain the same, and the outer diameter still had to have a similar thread to the "milspec" version, it ended up being a little thicker. ITAR had nothing to do with it.

Which one is better? the "milspec" LRE is forged from 7075, while the "commercial" LRE is extruded from 6061. The "commercial" version is thicker along most of the body, but is the same thickness along the length of the threaded area due to the constraints listed above. The threads also tend to be rounded on the "commercial" version rather than sharp as per the "milspec" LRE.

For most users who don't abuse their ARs or run them hard, the "commercial" version will be adequate. Others, including the military, opt for the "milspec" version. The other difference is that some manufacturers do not make stocks for both sizes, so if you like a particular brand, you should look at what sizes are available before deciding on which LRE to buy.

The one thing that should not change for either, is the necessity to properly tighten (not necessarily torque, but it is better if you don't have extensive experience regarding what is tight enough), and then stake the Receiver End Plate (often incorrectly referred to as staking the Castle Nut). Some people, and even some manufacturers, try to justify Loctite, but it is usually incorrectly applied, and can take more force and trouble to remove than staking. Staking is a two minute job using an automatic center punch, and directions are posted all over the net.

It just amazes me that some think this is not necessary, and yet we see people coming on forums all the time with problems caused by not staking (see the thread I referenced earlier). Strangely (or perhaps not so strangely) these are the same people that think that Tier 2/3 AR are "just as good as", and balk at spending a couple of hundred more on a rifle, but then go out and festoon their AR with hundreds of dollars worth of aftermarket junk, most before they have even shot the rifle once. And before you jump on this comment Angry, it is not aimed at you.

Regards.

Mark
 
MWL said:
It does appear to be "commercial-spec" from the look of the threads.

On a somewhat related matter, you need to ensure that the castle nut is torqued to 40 foot pounds and then properly staked.

Regards.

Mark
Click to expand...

Don't forget the threads must be lubricated before installing and only then torque to spec. Never do this dry like 90% of the folks do!

Personally, I find staking unnecessary when the tube is lubed and properly tightened. It will never come loose by itself.

Regarding receiver extensions:
The only sure way to know what you have is measure the diameter with a mic or vernier. Many tubes, but not all are mil-spec size with a 90 degree back. Over all length and number of position detents are not a guarantee either.
 
Angry by name ...

Angry,

If anyone jumped on someone's post, it was you. I advised the OP to stake the LRE, and you stated it was not necessary. You also made the assumption that because I am "new", I need you to watch out for me and the advice I give.

You did not explain why, give any alternatives, or offer any advice regarding them getting someone else to do it, etc. You just stated that I was wrong, although we both apparently know what can happen when the guy's castle nut backs off a little. It may never happen, but if nothing ever happened, we wouldn't need insurance, and I would also be out of a job (the current one, that is).

Regarding that issue, I have currently have a day job (although I seem to work a lot of nights for a "day" job), but that doesn't prevent me from doing something I have done for a long time (and make some pretty good pocket money at the same time), nor does it mean that I have never used or relied on a weapon in my previous employment, but that discussion is not for an open forum. I am certainly not 16, and I don't live in my parents' basement (oh to be 16 again though...). I have as they say, seen the elephant.

This is one of the reasons I generally don't go on many of these forums, and don't post much. I can almost smell the testosterone coming out of the screen on forums like this. Guys who would probably lend you their last dollar, or buy you a beer, act like dicks.

I really need to rethink this whole forum thing, in the end, I really could care less if no one pays any attention to what I have to say, and in most cases I could care less about what most other people have to say, so why I even bother, I don't know. I only really come on here during quiet moments at work. Maybe I should just take up knitting or something.

To the OP, my apologies for derailing your thread. It's your rifle, do whatever you want.

Regards.

Mark
 
Liberal-hater,

Good catch on the lube. It slipped my mind, even though I did one last night. I use Never-Seize or something like that, which I got from NAPA, rather than lube. I use the same stuff when installing a barrel, you just have to make sure it has no graphite (I think it's graphite) in it due to the reaction it can cause between the aluminium receiver and steel barrel.

We will have to agree to disagree regarding the staking, as I have seen castle nuts loosen, and those weren't even lubed, which I would think makes them easier to remove.

Regards.

Mark
 
mmattockx said:
Here is my dumbass black rifle rookie question for the day. Why are there two different tube diameters? Is this a US ITAR related issue?


Mark
Click to expand...

Nothing to do with US ITAR.

Military receiver extensions are machined from solid 7075 T6 and feature rolled threads for strength. This makes the thread's major diameter larger than the tube body.

Way back when aftermarket manufacturers came along to get a piece of the civilian market, they came up with a way to make extensions for less cost. Extrusions were used and had lathe cut threads. Because cut threads would have minimal strength if the tube was the military diameter (since cut thread major diameter is the same as tube diameter) a larger diameter "commercial" tube became standard.

As I understand it, 7075 does not extrude well, and so the more common, slightly less strong 6068 aluminum is used in any receiver extensions made from an extrusion.
 
MWL,

Fair enough. You last post was well written and you've made your point. In the interest of clarity, I'm not adverse to staking my receiver end plate or properly tightening a castle nut. The crazy part of all of this is that I AGREE with you. It is the best solution, of that there is no argument.

Anyway, I'm not going to press the issue anymore. I think the horse was beaten to death a long time ago.

Don't take up knitting (it's kinda lame), keep posting and offer your advise. In the grand scheme of things, the more info that is out there, the better.
 
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