Dakota R, also in the FAQ you will find the 2004 list of UPC codes for H&R/NEF rifles currently sold by Walmart, the link is there also to go to their current catalog so you can find the firearm you are looking for, print the page, take it to Walmart and place an order after they check availability, they don't need to carry it in stock for you to order it, all you pay is the cost as if they had it in stock, it usually takes from 3 days to a week for the firearm to arrive.
You can get a good handle on whether the firearm is in stock by checking Sports South's internet gun inventory since they are Walmart's supplier, if they have it in stock, hopefully it will still be in stock when Walmart checks availability at the time you order. Use the Mega search at the bottom of the page, select
H&R 1871 as the Mfr, and
long guns from the category, then select the caliber.
http://www.internetguncatalog.com/