I have been seriously tempted to do the same. The same goes for magazines. My next intended purchase will be a 308 rifle that accepts your standard SR25 pattern mags or Magpul mags. I dont have the money for the gun yet but I have thought the same as you.
I do ,however, have stocked a ton of brass for calibers I do not have. My local range, that I am very friendly with, lets me take all the brass I want when I go because they scrap it and dont make money on it. I even have left my brass at the range before when I have only shot 20-50 rounds because I am too lazy to bend over and pick them up and sort them. I currently have 7, 5 gallon buckets sorted and 2 garbage bags full of brass. The RO will even take the buckets of brass, grab a garbage bag and dump it in for me while I shoot. I will be very pleased when I actually get the firearms in those calibers. Especially some of the 300 Win Mag, 338 Lapua, 7.62x39 and other oddball brass I have found.
While saying all of this, I would like to give a little thank you to those awesome RO and Range owners out there. I would have to say I could not possibly ask to be able to go to a better range available to me.(except for longer distances) I have gotten many free lessons, borrowed equipment, free range time for testing their equipment(also for free), unlimited use of their range when I am the only one there(mobility and barrier set up on and down range). You name it, they have accommodated.
I don't mean to hijack the thread but besides all of you great people here on this online community, those of you same people are out there doing everything they can for the community and I thank you. People like you and me make this sport what it is and why this hobby is so gravitating. I think I can speak for almost all of us when I say it's more the people than the guns that we love so much. I love my guns, but my love for this hobby wouldn't be the same without the people.