I'm looking to buy/build a RRA varmint rifle for my brother. On www.adcofirearms.com you can buy a complete rifle for 843.33, but you can buy the varmint upper (complete with bolt,carrier,and charging handle) for 472 and a complete lower WITH the NM trigger group for 290. That only adds up to 760. Why is it almost 100 more to get the complete gun? Am I missing something? All I would have to do is order the upper and lower separately, slap them together, and I'd save 100 bucks?!? Thanks in advance...

If adco or anyone assembles a complete rifle for the purpose of selling it they must have a firearms manufacturing license and pay Federal Excise Tax on every complete rifle they manufacture.

If they sell an upper, no FET.
If they sell a lower, no FET.
No FET means lower cost to sell.

Thanks, that makes sense

Never too old to learn. I didn't know that either, but if you buy over the net you don't pay tax unless it's in the state you live in. I just bought a couple of lowers over the net, had them sent to a ffl dealer pre-paid and I didn't have to pay tax on them. If I had ordered a completed gun then would I have had to pay tax????

You still would not have had to pay the state SALES tax, which is what you avoid by buying from another state over the internet.  The company you bought it from WOULD have had to pay an excise tax to the feds, because it's a complete rifle, and would've most likely passed that cost on to you.

You'll pay your sales tax in the form of your local FFLs' transfer fee.

Just make sure that you pay for the lower yourself, don't have the gunstore buy it.  If they buy it and you buy it from them, you pay the sales tax.