Norc M4 buffer tube size ?

bobusboy said:
The term milspec needs to die.
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There is a very real difference between milspec and commercial receiver extensions ("buffer tubes"). Stocks intended for the smaller diameter military extension will not fit on the larger diameter commercial extension.
 
bobusboy said:
The term milspec needs to die.
Click to expand...

tjhaile said:
There is a very real difference between milspec and commercial receiver extensions ("buffer tubes"). Stocks intended for the smaller diameter military extension will not fit on the larger diameter commercial extension.
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From a previous thread on the same subject:

MWL said:
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.
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Mark
 
wildernessguy said:
Newbie question..... Would anyone happen to know how many rounds it takes before you replace a buffer tube, or a gas block? If they require regular swapping, I should have replacements on hand.

Thanks
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Now thats an interersting question. I'm thinking you would be replacing most of the rest of the rifle before either of those parts need replacing. The barrel will shoot out long before the block needs to be replaced, you will replace the gas tube sometime althought in firing over 75,000 rounds from one of my AR's, the SGW in the photo of me, I have replaced the barrel once and a bolt head once, thats all. Other that regular lubing and cleaning, for those who know me I clean when stuff stops working, I've never replaced anything on that rifle and it still chugs along!

Scott
 
m39a2 said:
Now thats an interersting question. I'm thinking you would be replacing most of the rest of the rifle before either of those parts need replacing. The barrel will shoot out long before the block needs to be replaced, you will replace the gas tube sometime althought in firing over 75,000 rounds from one of my AR's, the SGW in the photo of me, I have replaced the barrel once and a bolt head once, thats all. Other that regular lubing and cleaning, for those who know me I clean when stuff stops working, I've never replaced anything on that rifle and it still chugs along!

Scott
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Ah okay, that is likely why I didn't see any info on the subject when I searched online.......:redface:
 
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