...said he would make the purchase for me using his LE discount.
Surprised no one has used the term "straw purchase" anywhere in the responses. Just sayin.
Yes, this obviously COULD be an illegal straw purchase if the buddy is actually purchasing, paying for, doing the 4473/NICS thing.
But there are ways around it.
We all know of these retailers who sell discount guns to emergency personnel. Websites are most easily dealt with in this regard. Take BudsPoliceSupply.com for example. If you have a buddy who is an EMT or volunteer fireman, he sends his credentials to them while you send a money order and a copy of the receiving FFL's license.
You would receive the transfer via 4473/NICS in your state, for the gun you bought with your money, although qualified for a discount with your buddy's credentials.
This is not as easy in a store front, in which layaway would have to be utilized so that you could actually be the one to pay for it, and receive through the 4473/NICS process.
AFAIK, treading through this is technically legal, but ethical? Not really. If the OP's buddy was to acquire the rifle through a LGS the way I described in my first sentence, it is a text book straw purchase and IIRC, a federal felony.