kuanomar,

If you ever do need to use your R-15 for home defense or even CQC:
a little trick I learned from a Marine buddy of mine, since the corps issues M16A4s across the board standard issue, they've had to deal with the unfortunate fact that the M16 is a tad unwieldy in tight spaces. Something you may want to consider then, is placing the toe of the stock over and behind your shoulder and planting your cheek on the stock. it won't allow for precise shot placement, but it will allow you to manuever that 20 inch (I'm assuming) barrel around the corner, while at the same time bringing the center of balance closer in. I don't know how much the .243 recoils either, so I'd try it out on the range and see if it a works without bruising. 5.56 doesn't recoil enough to make this trick difficult, but I [censored] sure wouldn't try it with an AR-10. a foregrip does help a lot, if that's also an option for you.