Apple may have sold five million iPhone 5's in three days, but perhaps it could have sold more if certain U.S. retailers had been supplied properly.

According to The Wall Street Journal, Apple's own retail stores had plenty of iOS 6 handsets to go around. However, Best Buy, RadioShack, and Target were given the short shrift.

The paper's sources claim these retailers had a limited supply before sales even began, with some locations not even receiving enough phones to fulfill pre-orders.

Bare on pre-orders

At one Best Buy location, only 10 phones were reportedly delivered in time for Friday's launch, while at one Target, only eight phones reached its doorstep.

A Target spokeswoman wouldn't tell TechRadar much about the initial supply it received from Apple, however she did say demand was high.

"Target was able to fulfill many iPhone 5 pre-orders with the inventory we received, however, not all pre-orders were fulfilled," she said.

"We're working closely with our partners to fulfill remaining pre-orders as quickly as we receive inventory."

iPhone 5 wait time

Shawn Score, president of Best Buy mobile, told some customers in an email Friday that it could take as long as 28 days to send out pre-orders.

The problem, Score said, is that Best Buy's supply is low.

Non-Apple sellers of iPhones have experienced shortages in the past, though the disparity was reportedly greater this time around.

Sprint retail stores also reportedly ran low or completely out of iPhone 5's at some East Coast locations on Friday, though there is no indication at this time that is due to a purposeful supply shortage.

Compared to AT&T and Verizon, iPhone 5 pre-orders at Sprint only accounted for eight percent of total orders.

TechRadar reached out to all Best Buy and RadioShack and will update this story with information from them if and when we receive comment.

TechRadar also reached out to Apple and will update this story if and when more information becomes available.

Via The Wall Street Journal, CNET, GottaBeMobile