FIRST question first, how much did you pay for it? that would be a big factor if you should rip it all apart and mod it, or sell it and start over. That is a true AP4 .308 carbine... more of a true battle rifle and not a long range set up. That set up would be perfect for close combat / hog hunting with a eotech or red dot, NOT long range shooting especially with the fixed front sight. If you are going to use it for some hunting, then 16" barrel might be the way to go to keep the weight down, but the scope you're looking at would be way too much. What kind of hunting? deer? any .308 AR SCOPED will be heavy. if you are using for deer hunting, then you need something that goes down to 3x power. maybe even 4x on the low end but no more than that.... change out the front gas block to get rid of the fixed front sight and maybe something 2.5 - 10 power. 3-15 super sniper scope might be an option also... think they are selilng on sale right now for $699 and they are FFP!!!! Now on to your questions.
1. get a .308 pmag, that's if you can find one right now. personally, I wouldn't pay over $30 for one right now. $20 would be a good deal.... pmags are really the only way to go.
2. PRS is a great stock. I have never put one on before so im sure someone else here on the hide can help you out with this question. keep in mind this is a HEAVY stock and will add considerable weight to the rifle.
3. you are starting out with a free float front so that's good.... troy rail is not bad! you will also need to change out the gas block also
4.) 6-24 for a carbine rifle like that might be too much.... I think personally, max mag for that rifle would be 16x... also that is a TRUE carbine .308 rifle with a fixed front sight... might be a pain in the butt with a scope at lower powers = reason why entire gas block would need to be changed out IF you're going with a high power scope set up.
5.) you might not want to hear this, but with all the changes you want to make, and by the sounds of the scope you want to use with LR shooting, you might be better off just selling the entire rifle and getting something more suited around your needs. THAT's if you're going to be doing more long range target practice than hunting. By the time you change out all of that stuff you would prob be better off just selling and buying something based more around long range shooting... something with maybe a 18" to 20" heavy to maybe even a bull barrel. If I was you and you really want to get into .308 long range shooting, I would consider selling your rifle, and getting a rock river 20" varmint bull barrel in .308 cal. If money is not an option, then you can't go wrong with a GAP, OBR, OR LMT. I think you would be amazed how accurate a varmint A4 bull barrel .308 rock river would be. I know the stock isn't all that "tactical" but I would stick with it as it would be great for a rear sand bag. If you got this rifle with a 20" bull barrel, THEN I would get a 6-24 scope!!! Make note that this set up would not be the best for hunting as it would be really heavy (pretty much ANY .308 AR is going to be heavy, but this is more of a bench / target only type rifle and would be WAY to heavy dragging thru the woods). Now that would be a bad ass set up IMO for the money..... IMO, accuracy VS money invested, you can NOT go wrong with a rock river... about the only downfall to rock river .308 rifles is you can NOT use pmags, but rock river mags really are not that hard to find for an OK price. See links below for ideas. IMO, I would sell your rifle and start over. Might even still get a great price if you sell right away before the market goes back to normal. Who knows, you might even get more than what you paid for it. Armslist is a great online tool for selling rifles and I'm sure yours would sell really fast. Deal only face to face, CASH only. If you can, sell it for what you have invested IF NOT try to make some money for your scope purchase! If you do sell, then don't wait too long as prices are dropping like a rock:
A4 varmint stainless bull barrel:
Rock River Arms: LAR-8 Varmint A4
somewhat the best of both worlds with stainless heavy barrel:
http://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=402
just for example... at today's still crazy prices I think anything $1800 and under for a bull barrel .308 rock river varmint AR would be a good deal.. $1500 to $1600 would be great in today's standards!! IMO, 20" barrel would be perfect... some would say go 24", but I don't think it is needed and only adds weight. This rifle with a harris swivel 3" to 6" bipod, larue LT158 mount, and vortex PST 6-24 FFP scope would be a bad ass little set up for the money:
this actually has an adjustable stock and is not bad, but would kinda suck for a rear sand bag..
ROCK RIVER LAR8 308 20 INCH VARMINT COLL STOCK : Semi Auto Rifles at GunBroker.com
I just bought a DPMS AP4.308 and its my first .308...but not my first AR. I am a newbie to LR shooting but very interested in it. So I have a few questions for you guys?
1.What's up with these crap metal mags they come with that don't feed for SH*T???
2.My rifle has a collapsable stock and I want to but a Magpul PRS on it. Do I have to change out the Buffer, tube, and spring? and if so which one and how much?
3. Looking for a new rail. Thinking about the Troy Battle Rail TRX...any likes or dislikes? also realize I need a gas block instead of fixed front sight...any suggestions on those?
4. The scope im looking at putting on it is the Vortex Viper HS LR 6-24x50 FFP...Over kill or no? I have no idea about the difference from MIL and MOA but from what ive been told I need to decide which one I want

I am wanting to do some descent long range target shooting and some hunting with it. Any suggestions??
Thanks guys!
View attachment 5197