Help me pick an ar15 upper


November 9, 2006, 03:27 AM
So I'm in need of an upper for an ar15 that will be a range toy and personal protection rifle. I'm not entirely sure of what I want yet but I have some basic guide lines:

16" 1:7 twist chrome lined barrel
midlength gas system
phantom 5c2 on the end
A2 front sight
folding rear buis or the larue (eventually putting an eotech on)

it sounds like floating handguards can help accuracy even inside of 100 yards and when shooting off a rest, plus I will probably put a light on it eventually so I'm thinking larue rails. Can I put the 12" rails on a 16" barrel with a midlength gas system just for extra flexibility or is that dumb?

Past that I'm not sure. I'd like a quality upper receiver (hear good things about LMT usually). I'm to the understanding that the bolt and carrier can be sort of a weak point and that perhaps a magnetic particle tested bolt might be a good idea. Is that worth it? I would like the utmost in reliability. How about the LMT "enhanced" setup with 2 springs?

Anything you'd suggest I do differently? Am I going to regret the standard charging handle?

I was looking here but there are sever 16" midlength uppers available. Is barrel profile the real difference? Is government contour the one I want? They call that package "CMMG 16” Mid-Length Upper"

I am open to building on a midlength vltor vis platform but that seems to add $200 and no real benefit other than looking nifty since I can't see wanting to put the eotech where the nut is.

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November 9, 2006, 04:30 AM
CMMG is the way to go. You're halfway there.

The 12" rail over the block would be very slick - and handy. That's a good setup. I like the Daniel Defense rails, myself.

As for the bolt carrier, MP tested is a good option too, I see no real need for enhanced bolts....never had a "regular" one give me a problem in 15 years of shooting....but YMMV.

RRA 2-stage, nice optic, and you're singing my tune. :evil:

November 9, 2006, 02:14 PM
so the 12" rail on a 16" barrel isn't too dumb then? :D

Bartholomew Roberts
November 9, 2006, 03:55 PM
A 12" rail on a 16" barrel seems downright smart if you are shooting quite a bit - better protection from the hot barrel, more real estate to mount and better sight radius for irons.

The only downsides I can see are additional weight and potential problems with some reflex suppressors.

November 9, 2006, 07:14 PM
Never even thought of brushing the barrel down that but thats a good idea.

I've been looking at the monolithic uppers too, think I'll be happy with my eotech toward the back or is being able to push it forward a possibly nice feature?

Bartholomew Roberts
November 9, 2006, 08:20 PM
Eh... I was all hot for a monolithic upper when they first came out; but after thinking about it, there were already plenty of mounts on the market that were able to mount in that position with a barrel nut/collar in place. Basically, it only comes in handy if you want to mount in the position right where the barrel nut is on a regular rail and there isn't already a mount made that does that (like the ARMS #22M68 with the forward rake, the Larue EERs, Larue Eotech mount or any number of other mounts).

You can still mount on the receiver or forward of the barrel nut. There is also some evidence that the barrel nut of a standard railed free float acts as a better heat sink (though the monolithic uppers appear to be more rigid and M203-ready).

Six of one, half a dozen of another.

November 9, 2006, 08:58 PM
I went with the YHM modular forearm over an Armalite midlength barrel on a CMMG upper. The good of it is that it's all standard stuff (no proprietary dimensions) and I only have to deal with the bulk and edges associated with rails where I absolutely want it. The bad of it is that the forearm rail isn't naturally indexed to the receiver rail and takes some fiddling to get right, and the timing of the forearm rail slots isn't sync'ed to the receiver. This means that I can't 'span' the barrel nut with any kind of mount, but have to use a cantilever if available and desirable...

JP makes a float forearm that looks to be time-able to the receiver for less than $200. I have a variant of it on my AR10 and am very happy with the build quality.

November 10, 2006, 03:28 AM
So how's the whole setup work out if I want a fixed A2 style front sight, mid length gas system, and 12" rails? The rails would extend past the gas port and the sight post should be on top of the gas block right? Does this mean to use the full length rails on a mid length gas system I need to use a folding sight or do I just not fully understand the build?

November 10, 2006, 04:18 AM
Soy, with a 12" rail you'd buy a "rail height" sight, which is shorter than one that mounts to a gas-block. Std. A2 or flip sights are available in this height.

Look at this S&W M&P15T for an example (these are 10" Troy Ind. rails, but the concept is the same)

The front sight is folded down in the pic but you see where and how it mounts.

November 10, 2006, 07:17 AM
The Rock River catalog that came with the trigger group I ordered a month or so back mentioned a neat upcoming upper receiver -- flat top/rail but with a built-in mount at the rear for a fold-down sight. Looked like the best of both worlds to me. The rigidity of built in irons, and the "out-of-the-wayness" of folding backups, right in the position you'd normally bolt 'em on.

I don't know if it's out yet, but that's prolly the upper I'll be looking for when I do what you're doing now. :)

As to the whole long-long rail system.. personally, I don't see much of a neat. A flat top for optics seemsfine to me, and there's plenty of forward grips that mount to standard handguards. As a civilian the whole IR-laser-target-box thing is pretty useless, and that doesn't seem to leave much left to bolt on other than possibly a light.

But enh- to each their own. :)

November 10, 2006, 03:55 PM
Hmmm so semi or full auto carrier? Anodized ramps or extended/polished ramps?

On a 16" barrel would the 13.2" rails fit best or the rifle length 12" system?

Soy, with a 12" rail you'd buy a "rail height" sight, which is shorter than one that mounts to a gas-block. Std. A2 or flip sights are available in this height.
How about for a fixed A2 style front sight? It looks like daniels defense sells rails that have notches cut in the front of them for such a purpose. Does that mean no rifle length larue rails with a mid length gas system and a2 front sight?

November 10, 2006, 04:17 PM
I just purchased the larue 13.2 rails for my 16" carbine. The rails are very very nice about as heavy as the ARMS SIR I had installed before. I have to wait for the action block I ordered to arrive so I can install them. I'll try and post some pics after I get them set up.

Bartholomew Roberts
November 10, 2006, 05:38 PM
The 13.2 rails are designed to allow you to mount a front sight at the front of the rail and have the exact same sight radius you would with a standard 20" front sight base. The 12.0 rails are the same length as 20" handguards; but if you mount the front sight on the rail, you are 1.2" short due to the difference between the front of the rail and the front of a 20" FSB.

I haven't seen any full length rails with a cut for a midlength front sight base; but they may be out there. So many people make rails now that I can't even keep up with the new products offered by the few manufacturers I do know.

November 10, 2006, 08:55 PM
the rifle i rebuilt last month is strikingly similar to rbernies'

i've been shooting it like this (

until, after putting over 6000 rnds through it, i discovered it wasn't twisted as advertised and wouldn't stabilize my 100g bullets.

so i rebuilt it like this:



47652 it's a 16" midlength ss 1:7 wylde-chambered barrel from WOA with a low-profile JP adjustible gas block and the same rifle-length modular forearm rbernie's using. as you can see from the pics, i've got a rail on top that runs the length, and a short rail on the 3 oclock rear for my brass catcher and a short rail on bottom for the vfg. there's a vortex fs w/ and w/o can. i also replaced the aimpoint with an acog ta31f-rco model too. and for no good reason, i tried a TiN carrier.

i tried their specter length forearm, but i couldn't fit the spiffy end-cap on it because it was really made to cover up a carbine length gas block, so i put the rifle length on it. i like it better anyways, because of the way i use the specter gear sling.

in any case, the weight is very much improved and i highly recommend the modular YHM rails. all the YHM forearms i've ever used have been great, and they're like, 1/2 the price or less compared to DD and KA etc

ps two thumbs up on the TiN carrier so far, and the adjustible gas block gets 1 thumb up

November 10, 2006, 10:06 PM
Ohh okay so traditionally the front sight is part of the gas block so if I wanted a rifle length hangguard on a midlength gas system the gas sytem would be totally concealed so the "standard" a2 front right isn't an option and I'd need to use a rail mounted front sight?

Here's the cutout thing I saw

Bartholomew Roberts
November 10, 2006, 10:13 PM
Hmmmm, I'd ask before I bought but the 12.0FSP might work with a midlength. The 9.5FSP is for a carbine though.

Otherwise yes, generally people using a full length rail on a midlength will use a rail mounted sight. If you are willing to go to a 17" barrel, you can use a rifle length gas system and rifle FSB at the end of the 12.0 rail though.

the rifle i rebuilt last month is strikingly similar to rbernies'

I am starting to see some common trends here:

If we get BozemanMT and Zak_Smith to throw up some pictures of their rifles, it will look like an AR15 family reunion. :)

November 10, 2006, 10:55 PM
Thanks for all the help, I think I'm piecing it all together. I'm leaning toward a 13.2" rail on a 16" barrel with a midlength gas system. I kinda liked the idea of the fixed sight on the gas block but really it almost seems like a better idea to have the gas block safely tucked away under the rails and not have anything else clamped to it or exposed. I'll pay a little more for a sight but... Anyone ever twack their front sight and take out the gas glock or is it too secure for that?

Any thoughts on semi or full auto carrier and anodized ramps or extended/polished ramps?

Bartholomew Roberts
November 10, 2006, 11:03 PM
Anyone ever twack their front sight and take out the gas glock or is it too secure for that?

I've seen A2 front sights get bent; but never to the extent they impaired mechanical function at the gas block. A rail mounted sight is very secure. About the only problem I can see with them is they remove the benefit of the free float tube when using irons (because irons are mounted on the rail, sling pressure once again affects front sight). Not a huge issue; but something to be aware of.

Any thoughts on semi or full auto carrier and anodized ramps or extended/polished ramps?

The semi or full auto carrier isn't as important as having a shrouded firing pin. As long as you have the shrouded firing pin, either one is OK for use in a semi. As to the ramps, I like the extended ramps if you are shooting a lot of the heavier 75/77gr stuff. It has a longer OAL and tends to hit right below the normal feed ramps. It doesn't really affect function much that I can tell; but if I am going to spend money on high dollar match rounds I'd prefer they not get slammed nose first into the upper receiver and then pushed until they find the standard barrel feed ramps.

November 11, 2006, 09:09 AM
If we get BozemanMT and Zak_Smith to throw up some pictures of their rifles, it will look like an AR15 family reunion

Ok, per request.
These are mighty mighty custom (and in PD's hands after being stolen, so hopefully they come back)
However, I think they are almost perfect. Lightweight, fast handling, better accuracy and more verocity out of the bullet out of the 17" barrel and easy shooting with the full length gas system. The whole rifle probably doesn't weigh more than 6.5lbs

RRA two stage trigger lower with a Magpul 93b stock.
MSTN built upper (these guys are the best BTW, with a 17" Krieger 1:7.7 barrel with a full length rifle gas sytem and a MSTN compression brake, PRI carbon fiber full float front end with rails attached at the right points. You could put them anywhere, Troy BUIS, ACOG (TA31 on one, TA11 on the other)

Not cheap, but worth every penny. The rifle is much more accurate than I am. The only thing I'd add would be one of those ERGO grips, I've got those on another rifle and they are slick.

November 11, 2006, 12:15 PM
I am starting to see some common trends here

yeah, that is interesting... m93b stock, rifle length forearm on 16" barrel, RRA 2stage trigger

seems like everyone likes a different grip though

November 14, 2006, 05:14 PM
Pics as promised.

April 24, 2007, 01:10 PM
This might be the definitive, and mercifully short (not to mention mercifully free of flames / trolls / asshats) AR thread.

Out the door, what does cost? My estime is about $1300 for the rifle plus accessories, and another $900 for the sight. Is that ballpark?

Thanks for helping the new guy.

April 24, 2007, 01:27 PM
for my upper (last year's prices mostly from arfcom's EE):

$374 for the whiteoak barrel and bolt from globaltactical
$99 for cmt upper
$168 for yhm forearm, end cap, 3 rails, swivel, shipping from bright flashlights
$92 adjustable gas block and tube from JP
$45 for vortex FS
$155 for charging handle, titanium nitride bolt carrier, key, screw, cam pin, firing pin, shipped from dpms
$36 CQB sling shipped from spectre gear

for the lower,
magpul M93b stock was about $234
magpul miad grip was around $30
RRA NM 2-stage triggers are $120 (now, but i think i paid a lot less last year (edit: $88 from legal transfers))
plus you'll need a lower and parts kit

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