I just received one of those new DDLES Glock lowers from Gunbroker today. The mil-pec buffer tube I have isn't threading on. It just locks up after a few twists. The tube threads onto my other lowers just fine. What's going on here? Is there something I'm missing?

You pretty well answer your own question,,  spin nicely into lower "A",,  does not fit lower "B"....

Probably need to chase threads with correct tap.. that'll likely cut off the anodize coating to raw aluminum..

That's an expensive tap...  

 

Quick    "WTB"  (Want To Bum) tap post might get a loaner for shipping both direction..   Start in Hometown Forum and see if maybe somebody have tap that big..

Taps are indeed expensive...

I think I'll drop by my local gunsmith to see of they can work on it.

Take a picture of the lower...Show us what you're working with over there.

Contact the seller.....it it got threaded incorrectly, they will take care of you.
If you decide to thread yourself, and something goes wrong, you are screwed.

think this lot were blems or ones that hadn't sold off before seizure for a reason?

Could be possible. Can't say for sure though. Aside from the buffer tube issue, the lower was immaculate.

Anyways, I spoke with Russ, the seller/guy that took over DDLES, on the phone the other night. I just sent my lower back to him today to be exchanged. The guy is pretty legit and is working very hard with getting the business back on track. He says he's got his own branded product in the works as well as a bunch of other goodies. You guys will be hearing from him really soon. He has my confidence and I'm going to continue doing business with him.

Pics will come once I get the new lower in.