Friday, December 20, 2013

AR-15 buying, need help

In the crush of finals, I forgot that people consider graduation to be an important thing, and that some people will send you money for such things. As such, should I opt to spend it rather than saving it in the incredibly pessimistic case that I'm unable to find any sort of job, I have sufficient money to buy a cheap AR-15.

I guess then, that I should figure out exactly what I'm after. This will be my "main" gun, the one I reach for in 99.9% of all cases where I need a gun and have the luxury of choosing one not strapped to my hip. As such, it needs to be pretty good at basically everything, an acceptably general purpose arm.

Things I'm looking for in my rifle
Dissipator: longer sight radius for more precise use of irons, while still being as short as is legally convenient. Might opt for mid length for cost and convenience of parts if I have to
Collapsible stock: Pretty self explanatory, WI doesn't have any stupid laws that say I have to do otherwise.
Flat top: Don't have much use for a carry handle, and I've got a 4x lying around and have plans for a red dot on this thing for general purpose use. If such a thing existed, a 1-4x scope would be good too.
Rails: I need at least a moderate amount of rail space. I plan for this to have a light, laser, red dot, and probably a vertical foregrip. I also want a bayonet on this thing, and will probably have to design my own rail-mount one because I'm dumb and want a dissipator.
Semi-light weight: I've got a $120 complete lower receiver I'm looking at that's polymer and has gotten great reviews, but I'll probably go with a heavy (not bull) barrel, and I'm gaining a few ounces from extra hand guard length
Barrel: I've heard that 1:7 is preferable to 1:9 for a 16" barrel. I'll take what I can get and buy ammo accordingly, because I'm trying to do this on the cheap at present. As mentioned, heavy profile barrel sounds nice.
Magazines: I'm actually tempted to buy up a bunch of Magpul 40 rounders instead of 30 rounders, because they aren't much pricier or larger for a fair deal of increased capacity. Hoping they come out with window versions of the 40 rounders.

Here's the pieces I've got so far if I do it piecewise (they have a dissipator full rifle kit that's never in stock for $500+ a stripped lower receiver)
LW-15 lower receiver
Complete dissipator upper
Magpul MOE handguards
Flat top upper
16" dissipator barrel

If I can save sufficient amounts of money buy assembling things myself, I'll look at optics and other such things. Yes, I'm aware that optics have a minimum price before they're actually decent.

I have absolutely no idea what I'm doing. I have no idea how del-ton handles it, but I know they make parts kits for some of the big names. If you know where to find deals, or can see something I'm doing horribly wrong, let me know. Any help is appreciated


  1. Make sure you're getting a real dissipater and not just a 16" rifle barrel.

    HUH? You say.

    A 16" barrel with a rifle gas system often doesn't have enough dwell to cycle when the mercury dips below "hot summer day". This is why the Colt R605 was an abject failure and they returned to the drawing board to give us what's known as a carbine length gas system.

    The original dissipator is a 16" barrel with a front sight base in the rifle position and a gas block in the carbine position. This is the configuration you want. Lots of places selling "dissipator" barrels don't do it this way.

    For a 16" barrel, the middy gas system is really the ideal. Port pressure is lower and dwell is about right. A 16" with a carbine system has high port pressures and those are held longer by the longer dwell time (The ideal dwell for a carbine gas system is near a 14" barrel; 14.5" was adopted because it has the same port-to-muzzle distance as a rifle because bayonet).

    Since you intend to use optics, why worry about the sight radius of your back-up system?

  2. Yeah, I know about that with dissipators. I know lots of the specifics about such things, but I've never shopped for them and have no experience with trying to tell when bits I need aren't there, or such things as what the length of the gas system is. Definitely want a mid length gas system with the false gas block up front for the front sight, the question is being able to be sure that's what I GET through online, where I expect to buy most of the parts from.

    Honestly, the main reason I want a dissipator is just that I like the look. However, I plan on ONLY having a red dot, with a 3-5 MOA main dot. I can manage ~1 MoA pretty reliably with irons. My plan is to use optics for general purpose things, and switch it off and do it the old fashioned way if I need to really get down to as high precision work as is possible without magnification.

    To be fair, this will be upgraded/replaced probably when I have money to shell out for high end parts where they actually count, so I suppose there isn't much point in trying to get it perfect to what I want on the first try, particularly if doing so adds cost and risk of getting stupidly made parts that don't work right

  3. You're probably not going to find a mid-length gas system dissipator. They're all carbine gas (if done correctly). Del-Ton's barrel is rifle gas.

    I guess you could have a custom barrel turned, but that's a lot of money for a cosmetic feature.

    Carbine gas on a 16" tube is overgassed because of excessive dwell, but it's not the end of the world. You can compensate for it by adding mass to the reciprocating parts. Use an M16 bolt carrier and get an H2 buffer. A stronger extractor spring might be needed, but only if you're having problems. The nice thing about carbine gas on a 16" is that it's VERY common and that means all of the potential kinks are worked out.

    Don't pay extra for M4 feed ramps! Don't avoid them either. They're a change to make full auto more reliable and don't do a thing for a semi-auto. They don't hurt anything to have them, but some places still charge a premium.

    Don't get hung up on an F marked front sight. Most guns will zero without the extra 0.040" of height, especially at the rifle length.

  4. Color me corrected...

    PSA is a good company.

  5. I know at least a few companies make dissipators with a mid-length gas system, it's just a matter of if any of them make it for the price point I'm looking at. I'll probably go for a Bravo Company mid length, since they have a few of them that are dissipators in all but name (full length/extended handguard on a mid-length system), since from what I've heard they make some of the best quality stuff. It's priced accordingly, which is why I probably won't be starting with it. I have no idea what my actual max money I could spend on this is, I know I'll have more than I actually want to spend.

    For the $400 that PSA is when not out of stock and still on special, I might just go with that one and spend a touch more to know that I'm getting quality. From what I've heard a few parts of the upper are the big factors in getting good reliability, so I don't mind spending a bit extra if I have it to get something I know will work better.

    I'd seen that stuff about the different types of feed ramps and marked front sights and whatnot, and had no idea what it was all about, thanks for clearing that up.

  6. McThag gives sound advice.

    Thread on PSA here:

    Personally, I'd probably just buy my upper complete from either DD or BCM. "Buy once, cry once" and all that.

    There are good 1-4X variables out there. Check out the Burris MTAC.