Originally Posted by fatmidgets
I thought an AR in the x39 caliber would be a very versatile weapon for hunting/defense/target shooting. Ammo is cheap, and the ballistics are pretty good for a short-medium(50-200 maybe 300 yards) range weapon. Also I just thought it was cool, because I like the caliber, and the AR platform is more accurate than the AK. Also, I don't really care to own the 5.56x45 caliber. I already have a remington model 700 in .223.
x39 is not an ideal round for SD as compared to others. Bullet tech is low while rounds like the 5.56 and .308 has some great options. I wouldn't trust a x39 AR for defense even though I had one that eventually worked well. Recoils is harsh compared to more reliable options which will effect follow up shots.
If you want a x39 look into the .300 Black Out. Is has similar/better ballistics w/ a better range of projectiles. You'll be looking at a minimum of $130 per 200 shipped for ammo but it's well worth it (cheaper than x39 factory brass). It has proven to be very reliable out of the AR and the only part that is proprietary is the barrel. All other parts required are simply 5.56.
Look into 5.56 if cost is an issue like it is for me. It's reliable and ammo can be as low as $3-$4 per 20 or $189 per 1k. They also have some great defense ammo.
If you do decide to go x39 contact Performance.com and ask about a 16" midlength gas system w/ their Super Bolt.