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What makes a good AR15 lower and why?

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Arizona_Mike

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I'm probably going to SBR a lower and don't want to waste the increasingly absurd time involved on a lower I will outgrow. What makes a good lower and why?

Mike
 
All you really need to ask of a lower is that it's 7075 forged aluminum, has a good Type III anodized finish, and is in spec.

Plenty of brands (I says brands because many of them come from the same manufacturers) can deliver that - BCM, PSA, Spikes, Colt, Aero Precision, LW Schnieder, etc., etc.

As far as parts, there's not really any way to outgrow a lower. You can always upgrade or replace the fire control group, grip, or stock.
 
Don't let any one tell you that there is a big different in them. It is a way to get you to spend money. The post above say it all!
 
I spent extra on a Noveske lover that has a really THICK extended trigger guard and flared magwell. Those two features certainly added a 'premium' vs.. a 'standard' lower.
 
many lowers are forged by only a few different company and then roll-marked with someones logo. basically, pick a roll-mark you like and youll be fine.

that being said, i spent a little more and went with a Mega Billet lower for my SBR. i feel its a little beefier than the standard forged and i like the features of it. plus its about 50 bucks less than the Noveske with the same features.
 
Pick the one that you think has the coolest roll mark on it. Beyond that they are all pretty much the same
 
Receivers all little more than a housing and your accuracy is going to come from the barrel. A matched upper and lower will have a tighter fit. Mil spec name brand stuff is pretty much all the same. You can burn money on billet receivers but your money is better spent on a good trigger and barrel.
 
You can burn money on billet receivers but your money is better spent on a good trigger and barrel.
Click to expand...

This. ^^^

All a billet receiver adds to an AR is weight.
 
Fishbed77 said:
All a billet receiver adds to an AR is weight.
Click to expand...

Also....features not found on a standard forged lower depending on the manufacturer...such as a thicker trigger guard, flared mag well, finger grooves on the magwell. There are cosmetic benefits too, imo.
 
Other than dimensional issues I could imagine a lower not tempered or hard anodized properly would be a nightmare. I don't remember reading tons of threads about lowers with wallowing holes and such, so it must be rare. Any of the decent brand names should be good to go.

Where does Daniel Defense get their lowers?
 
On a lower that's used on an SBR, because if the time and tax invested, go ahead and get what you want. Its going to be yours for a while with your name or trust name engraved on it.
 
Also....features not found on a standard forged lower depending on the manufacturer...such as a thicker trigger guard, flared mag well, finger grooves on the magwell. There are cosmetic benefits too, imo.
Click to expand...

...all of which add weight without much functional benefit. But to each his own.
 
Other than avoiding a polymer lower, I don't think paying more buys you much. Get a well known brand and you should be fine.
 
Fishbed77 said:
...all of which add weight without much functional benefit. But to each his own.
Click to expand...

There is more to the billet lowers than you are suggesting. They are heavier, and not really stronger than a forged lower, but they do offer real benefits over a forged lower in functional ways. Maybe not in ways that interests everybody, but saying that they add nothing functional to a build is incorrect. If I were going for extreme accuracy, a billet lower matched to a billet upper can be machined to be truer to each other and more rigid than their equivalent forged parts. A flared magwell is more functional than a foward assist, imo.
 
some lowers certainly are substantially, functionally different and have a lot of features that the standard lowers don't. Whether that's better or worse depends on whether you want the feature or not.

among standard, forged lowers, i agree with the general consensus above that they are basically all the same. (jsut to be safe, i'd recommend assembling the lower parts and a regular upper just to make sure they fit before waiting 6mo and wasting $200)


that said, i've come full circle. having owned magpul, noveske, knights and other special lowers, i've come back to the simple but solid standard one as my lower of choice for new builds.

aesthetically, i think the magpul looks best, especially with the unobtanium china doll. though i'd give the seekins billet lower props for blingyest!
 
I picked up a Colt LE6900 Light Rifle some time ago and while I am aware of the limitations of the upper. The lower appears very well made and I prefer the oversized trigger guard to the milspec one.

Any reason not to use that one?

Mike
 
Arizona_Mike said:
I picked up a Colt LE6900 Light Rifle some time ago and while I am aware of the limitations of the upper. The lower appears very well made and I prefer the oversized trigger guard to the milspec one.

Any reason not to use that one?

Mike
Click to expand...

Good question! I quickly handled a Colt LE6900 a month ago and wondered the same. Wish I could have slapped on another upper. I suspect it's a standard lower, it sure looked like it. (Though not made by Colt). I also wanted to check if the receiver extension was milspec or commercial diameter. I suspect the latter.

Anyway it would be incredibly stupid to use a proprietary lower when a generic one would be cheaper.
 
Might I respectfully suggest that for a SBR, you procure and correctly complete finish one of the GOOD 85% lowers that are available? This way the required engraving on it will be YOUR engraving, not your engraving added to another set of engraving? You chooe the serial number, etc. Get help with the machining (it's easy), have it engraved, and then have it finished after the engraving is completed. You'll be far ahead.


Willie
.
 
Quentin said:
Good question! I quickly handled a Colt LE6900 a month ago and wondered the same. Wish I could have slapped on another upper. I suspect it's a standard lower, it sure looked like it. (Though not made by Colt). I also wanted to check if the receiver extension was milspec or commercial diameter. I suspect the latter.

Anyway it would be incredibly stupid to use a proprietary lower when a generic one would be cheaper.
Click to expand...
I haven't gotten around to slapping another upper on it (not sure why as I can just go to my safe) but I'm sure it will fit. The buffer tube is military diameter and the buffer itself is standard carbine weight. Those I have measured/weighed. In my limited experiance commercial buffer tubes tend to have a slanted end like this:
Buffertube_Specs.jpg
Mike
 
Thanks for that information on the 6900 AZ Mike! But the slanted back isn't always present on comspec tubes so the best test is to measure the external diameter or just see if a stock known for sure to be milspec will slide on the tube. Can you check this too?
 
I measured it wth calipers a long time ago when I got my Magpul CTR stock. It is military diameter.

Mike
 
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