Heads up, I'm a huge BCM fanboy, I have several uppers, and lowers from them. In fact I exclusively buy bcm uppers at this point, because until now they produced what i consoder to be flawless products.
All that being said, I purchased a complete FDE lower from grabagun.com for about $400. I got it home grabbed a mag, went to insert it, and it would not seat. I tried again, and again, and again. I got a sick feeling in my stomach as $400 is a hefty price for a lower (that won't accept my 50 plus Magpul Gen M3 mags) but I thought it was worth it for the BCM brand name.
The first thing I did was call grabagun.com, the very friendly rep told me she would send me a return shipping label, and my $7.99 shipping cost would be refunded as well. I asked if I needed to send via my FFL, and she said no. I asked if there was anyway a replacement could be sent instead, but she said all other BCM lowers, with the exception of a pistol lower were out of stock. I was pretty bummed and asked if she could check if any other BCM lowers would soon become available.
She placed me on hold for several minutes, then came back and told me that no refund could be granted, as it is now in my name. And I should contact BCM for any warrantee work needed on the product. I asked about the return I was promised, and she said she was mistaken.