Need not worry about straw purchase,
It is a gift. Perfectly legal as long as the person getting the gun is legally ablw to own one.
Not really any different that winning a gun thru a raffle.
As a raffle winner of a S&W "Patrol Rifle" from a local Chamber of Commerce several years ago, I know they thought the winner was going to have to do a 4473 and were surprised to find out that since the Chamber had already purchased the rifle then it became a gift through the raffle. I showed them my CCW card to let them know I was legally able to own a firearm then told them they ought to just go with a gift certificate at the local sporting goods store in the future.
As to rifles and roofing, I had to replace my roof last year due to the April hail storm. There has got to be at least 2 rifles up there somewhere...