Thread: AR lower
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Old 01-13-2013, 09:44 PM   #33
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Originally Posted by wrighterjw10 View Post
are any of the $300-400 AR15 lowers on gunbroker decent for just target and stuff?
That's difficult to say without knowing a brand/make. Will it be in spec? More than likely, yes. Price will not be a determining factor.

Each component has a tolerance that it has to meet to be in spec. That tolerance can be greater or lesser than the called for dimension. Problems start when the QC process is such that as long as a part is in spec, it passes.

So let's look at the upper and lower receivers. They are tested individually, and the QC guy tests (hopefully they have someone testing) the lower and spec is considered 3.0 - 5.0. The lower tests as 3.1 and is considered "in spec" and is passed and set aside. Now he is testing an upper receiver and spec is considered 3.0 - 5.0. The upper tests as 4.9 and is considered "in spec" and is passed and set aside.

Joe consumer buys an upper and lower, tries to mate them together and guess what? The take down pins barely fit and need to be hammered just to get them together, or they don't fit at all. But how is that possible? They are both "in spec"! Because the company isn't looking at the finished product as a whole.

Now look at a company like BCM (my favorite, my example). The same upper and lower will probably be rejected and sent back to the foundry (likely to be sold to the company above) because they will consider "in spec" 3.5 - 4.5 and both of the pieces would have failed.

These are BS numbers that I just made up for this example, but I hope you get the point.
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