Immediate Blisters

I ordered a size 10 and 10.5 Barefoot African Rangers. The 10 my toes hit the front slightly, but the 10.5 has TONS of room in the heel. Not so much up and down, but a side to side. They did slip up and down if I walked up stairs in my house. Since the 10 was definitely too short, I decided to wear the 10.5s today.

Within a mile of walking I already have horrible blisters on my heels. The worst blisters I’ve ever had! (Skin peeling off all the way around my heels.) I have pretty thick wool socks on, and the laces are as tight as I can stand them, but my foot can still wiggle around in the heel. Whose feet are these even for?!? I have never had any problems with heel space in any footwear before. I think the issue is that the shoe just doesn’t flex with my foot enough. I had some kinda poor fitting Thursday boots that these are replacing, but they weren’t nearly this harsh on my heel.

Any ideas/tips? Right now I just want to pour gasoline on them and light them on fire. Second pair of $200 boots that are a miserable hell scape.