ar 15 lowers

Originally Posted By: Lornewhat is the best tightest ar lower looking for a good lower for my new build

A virgin lower would be best tightest. LOL

Mil spec is just that.

 
Originally Posted By: Lornewhat is the best tightest ar lower looking for a good lower for my new build


The tightest fitting lower, is going to be a billet. Typically they are held to tighter tolerances than a Mil-spec forged lower.
If you are looking for a zero slop lower, look at a billet lower with a tension screw built into it. This will take all the movement out of the upper-lower connection.
 
I do 80% lowers and mill them to fit tight to the upper. I haven't had to shim one yet, as long as the uppers are the same dimensions your good to go. If your using one lower for multiple uppers.
 
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Fitment is going to very between every build. Some will require a punch to get the pins out and others will open easily. Many takedown/pivot pins aren't a true .250, either. A lower with an upper tension screw like the Spartan-15 Enhanced Lower Receivers will help on sloppier fits. Accu-Wedges can also help fix a sloppier receiver set.

Either way, a "tight fit" isn't crucial like it is on a 1911 for accuracy or reliability. It won't affect the way the rifle shoots.
 
As most any gun guy can see there is a bit of a glut in AR components that sold like crazy a few years ago. I got the itch to collect a few parts. So far I ordered a Mag-Pul MOE stock with a lower parts kit that was on sale at PSA. Then I got an 18" BCM upper.

I was thinking about the 'Aero Precision' lower advertised at a shop just over an hour away. I called one of my local favorites and he had some fresh 'Spikes Tactical' lowers in stock. I did some quick research and thought I may as well buy two.

I think I say that spikes is made by the larger 'LAR', which makes them for a handful of names. I talked a bit with the store owner about Spikes, seem to be fine. I went with the engraved spider over the zombi.
 
Originally Posted By: 3DHUSKER

A virgin lower would be best tightest. LOL

Mil spec is just that.



Just asking - who makes commercial spec lowers?
 
I've traditionally built on Bushmaster uppers and lowers, always had good luck with fitment. They're not so easy to get ahold of these days though, it seems.

I have 7 uppers and 5 lowers on my bench right now. One Aero, two Spikes, and 3 bushmaster lowers, with one "Joebob's", one two Aeros, and 4 bushy uppers - all of these fit together very well. I have accu-wedges on hand for all of them, but none really seem to need them, other than making me feel better mentally.

Gotta keep in mind, most forgings are actually produced at one of about a dozen places, no matter whose name ultimately ends up stamped in the side. Plus, even within individual brands, they may not exclusively source from one forge. In this set of 7 uppers, two of the bushy's and one of the Aero's were Cerro forges, one bushy and one aero were Brass Aluminum forged, and I'm not sure what the JoeBob's upper was - kinda wanna say Martin Marietta.

Maybe I've been lucky.
 
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