I have the AP4
It is very accurate, and reliable. There are changes that each user makes with any rifle (especially a lefty like yourself) and I made a few here:
The muzzle device is a little loud, and a 16" barrel certainly doesn't need any help with that. I added a Vortex, and it is quieter.
The trigger assy needed a little love. I took it apart and used a little 0000 steel wool and a LOT of elbow grease to make it nice. It breaks a little over five pounds, but now it feels "right".
The safety seems to sit lower than a normal AR. I had an ambi unit on there, an it bit my trigger finger. I have removed it.
The free-floated aluminum forestock gets HOT. After about 100 rounds of moderate fire, I couldn't hold it any more. I wear a nomex glove when I shoot it now, but we're talking HOT. I know of no way to solve this problem, as I hate railed forends, and really like free-floated systems. I'm working on it, but for now I just shoot it slower, or add a glove.
My gun was shipped BONE DRY with no oil of any kind on it anywhere. I was a little surprised, as normally rifles are shipped with way too much oil, as you probably know.
Mags are a little expensive, but not bad, really. Midway has them for $35 each, which isn't what I would call a deal-breaker, but it aint no FAL. I'm actually looking for more now, maybe used, as I somehow ended up with springs and followers left over.
The sights are really great, and mine required almost NO adjustment. I slapped the rear sight on, tightened the thumb screws, and fired it at 25M.
Three rounds touching. One half inch from my mark. I'm told this is not typical, as the sight shipped off the rifle.
This gun is lighter than a FAL carbine, and heavier than the SOCOM-16 (the original one) Not a bad weight, and in my opinion it balances better than the FAL carbine.
I did some magazine dumps with it, simply to test its rapid fire ability, and it really runs the brass out! I fired a little over five rounds a second until I had five empty mags, and like I said above, I couldn't touch the handguard, but it ran perfect. Accuracy didn't seem to be affected by the heat all that much, with the biggest group of Wolf measuring just under 3", and the smallest at right under 1" with M-118.
No failures of any kind the first day shooting it, in over 500 rounds without cleaning. (I did run a boresnake through the barrel twice in the beginning. I'm not one to "break in" a barrel) All the brass fell in the exact same place forward and to my left about ten feet. I shot 200 rounds of M-118, 200 of SA surplus, and 100 or Wolf. All of it was fine, and the brass looked reloadable after shooting.
I was shopping for a DSA Sa-58 Tactical, and picked one of these up instead. Price locally was $1005, and I bought ten mags from Miday for $340. So, for $1345, I had the rifle and twelve magazines. Can't say I could do that with any other .308 with the possible exception of the Saiga. The best part of the DPMS AP4 was that the entire bolt carrier group is hard chromed. Pretty nice work, too. It is a snap to clean, which is a plus in a direct-impingement system.
NC, I understand you already have a STG-58 carbine, and I believe the DPMS would be a wonderful companion to it. It is lefty-friendly, and the bull-barreled model is really very nice. No sights, of course, and no dust cover or forward assist. I handled one, and liked it, but wanted the shorty first.
Good luck, and if you every come to VA Beach, you can shoot mine.
Steve