What do you think of this AR build?

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Jul 6, 2008
Calirado (formerly Colorado)
What about the lower parts kit?

Good luck finding these at the moment.

I too question the polymer lower, its legally the gun, so why take a chance on something relatively unproven for your first build?
In regards to the poly lower...I've read mostly good reviews on it. I trust poly from using Glocks for many years. There are Bushmasters I've seen built with poly.

It has a lifetime warranty and NFA is a veteran owned, full service gun shop based in Las Vegas. Besides, it's only $89, so if it sucks I'll buy something else when the mass hysteria stops.

In regards to the commercial size tube, the stuff I read said it was sized for commercial buffer. Maybe they were referring to the companies actual built lowers? I'll have to give them a call!

Lower Parts Kit is the Core 15 one I listed.

I've found a good site for finding AR stuff actually in stock is: http://arpartsfinder.com/
I've tried to do business with NFA, customer service is virtually nonexistent. I would wait and get a PSA lower or something equivalent like a spikes etc., especially with that awesome upper; do it some justice.
I'd buy a 7075 stripped lower and milspec diameter receiver extension. And of course milspec CTR.

What will you use this AR for and how does the YHM upper fit into your plan?
I say no to the polymer lower.... They throw off the balance of the rifle, and to be honest, they have not been used long enough for me to trust them.

If you are buying the top quality upper that you are, I would never pair it with that lower.
I've never tried a polymer lower, but I have no real desire to do so. I'd personally opt for a decent forged aluminum lower, though those are somewhat hard to find right now. I'll also second the suggestion of a mil-spec diameter receiver extension.

As for the upper, I'd personally opt for something with a chrome lined barrel if the gun is for general use or a stainless match barrel if you are looking mainly for tiny groups.
Stripped Lower: New Frontier (Polymer) ($89) I wouldn't use this. I certainly wouldn't pay $89 for one. If you want a light weight lower and that is your reason for going polymer, I'd get a Cav arms one instead. If you are trying to save money, there is a better place to save $30. If you want to over pay for a lower right now you can buy a PSA lower for $119. I'd argue that you'd be better off say getting an MOE stock in place of a CTR and saving the money there.

LPK: Core 15 ($85)

Upper: Yankee Hill Machine XL Black Diamond ($820) Not what I would get, particularly if I had $820 to spend. The price of AR stuff is coming down right now. Now is the time to be patient IMHO. As for the upper itself. I have used a couple different guns with that rail. I'm not wild about it. It is kind of big, and not as light as other options. The barrel is not one I'd want. All the other YHM stuff on it is OK but not my first choice. Some of that is personal choice some of that is that there really is better made stuff available.

Stock: Magpul CTR (commercial sized) ($73) Why the commercial size? If you are putting it together and getting your own buffer tube I'd go mil spec.

Stock Assembly Kit: Omega Tactical on ebay ($32) Don't know anything about Omega Tactical so I can't comment.

Much of the above is based on my personal preferences based on how I use guns. YMMV. I think in the relatively near future there will be much better deals to be had. In the post '09 panic it was one of the best times to buy ARs. That may happen again. Even if not to that extent prices are still going to fall.
A further word about falling prices. The price of stripped polymer lowers on PSA's website has come down since this thread was started. They are still much higher than what I'd ever consider paying for one, but they are on the way down. They also are showing a lot more stock on uppers, lowers, and various parts for each than they have in a long time.
Personally I have no use for a Polymer Lower Receiver anymore than I have a use for a quad rail upper on an AR15. However, if that trips your trigger then buy it.

Just My Take
I'd also advise against the plastic lower, but that's not just a knee jerk reaction. I actually own two rifles that have poly lowers: a FS2000 and a SCAR16.

The big difference is those two rifles were designed to use plastics. In the case of the SCAR, the lower doesn't carry the stress of the buttstock, and the FCG pins are carried on internal steel plates, not on the plastic. The FS uses plastic for the stock, but the barrel trunnion is locked into it for load bearing. The trigger group pins get their own reinforced 'tray' for stability and strength.

You can't just sub out 7075 high strength aluminum alloy with fiber filled nylon on a 1:1 replacement and expect things to work out well.

The MOE stock is just as good and saves money over the CTR.

The polymer lower worries me slightly but my buddy's Bushmaster one seemed to work okay and I have several polymer handguns that I trust completely. I just don't know about that particular brand or it's reputation.

The buffer tube isn't a big deal really and you can usually find Commercial sized MagPul stocks cheaper than MilSpec on GB.

The upper seems nice and should make for a good rifle.

Lastly, I would spend another couple bucks on an Accu-Wedge. It's not essential but it tightens up the fit a a little more.

If you're in the thing $1200 for another $200 you can buy nice rifle that's already built.
daveit, I used Del-Ton parts LPK in mine, I had to file the bolt release latch opening a little but that was it, still havn't had a single issue with any of my 3, I like them so much I just ordered 2 more...
I wouldn't get a polymer lower for $50. You can find real lowers these days for pre crazy prices so there is no reason to use a polymer. And if you are going to spend $820 on a Yankee Hill upper you might as well get a BCM and call it a day. BCM is top notch and in your price range.

Also, I would get the mil spec stock, no reason not to.
Build update

Changed it up a bit:

I have almost all the parts, and I'll be picking up my lower tomorrow so hopefully I can get this built up this weekend!

Complete Upper: Yankee Hill Machine XL Black Diamond
Lower: Yankee Hill Machine
LPK: Core 15
Stock: Magpul CTR & BCM Buffer Assembly (milspec)
Foregrip: Magpul AFG
Grip: Magpul MIAD
Sling: Blue Force VCAS
Sling Mounts: Troy Industries Rail Mount & 2 GG&G Swivels
Mags: Magpul
Optic: Bushell TRS-25 (will eventually upgrade & move to .22LR)
Optic Mount: UTG Double Rail 3 Slot w/ QD
I recently bought a new, New Frontier complete polymer lower for $99. This will be my first polymer AR build, can't beat the price on that.
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