Is there a background check and 10 day waiting peroied for AR-15 upper receiver and lower receiver assemblies?

Online. Midwayusa.com I know haas them. Sometimes the upper and lower may not be perfect and cause wiggle.

This does not affect accuracy.

http://www.cheaperthandirt.net/ARR006-7.... Strictly speaking, they aren't seals or gaskets. Neither item is going to do any harm, in my opinion. As people have mentioned, eliminating uppper-to-lower receiver wiggles isn't critical for mechanical accuracy.

But it can give a shooter some peace of mind.

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