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BTT

There are some on gunbroker.com in the $240 range for a naked lower.

Ever use one?  Unless you're dedicated to one, you can complete any other conventional lower for way less than just the SOCOM lower.  In fact, in my area a fully factory assembeled Bushmaster lower with an A2 buttstock installed is going for $225.  I've built 4 of the SOCOM lowers 2 years ago, and one just recently for a buddy (5 total in the last few years).  

Heres my review, it may help you assemble one and avoid some of the problems with them if you haven't already done one, or encountered some of this:

Holes:  all of them are milled/drilled after the center of the lower cavity is milled out.  This leaves burrs on inside on every hole.  You really have to force each pin through the hole as a "Dry Fit" first before final assembly.  Some holes require lapping with compound or paper.

Springs:  Because of the unique design for using set screws to hold some of the pins in place, you have to trim some springs.

Set Screws: Hint, its a metric hex head!  Once you've completed dry assembly, and then done final assembly, use blue locktite and put it in so that it won't rattle loose (Yes, it will).  Oh, and there are pins that go in a few places, and you're going to have to trim those pins a little, too.

Overal quality:  Good.  BUT the metal is way soft.  It's very easy to overtighten and strip out the set screw holes.  Been there, done that.  The front holes are pretty good, but if you have a tight upper reciever fit, to the point that you have no play in the upper/lower and the rear pin has to be forced into place with more than normal force, you WILL wear the rear holes in the lower oblong (I have had 2 that have done this to some degree.  The anodizing inside the pin hole on the uppers is still there, thus indicating to me that the upper metal is harder than the lowers.)

Grip screw hole/threads:  Not in spec for the 1/4x28UNF grip screw and usually not cut all the way through to the inner cavity like a regular lower.  It is very tight.  In fact, all the screw holes on the lower are tight, like they were cut with a slightly undersized tap or the lower metal was not at room temperature when it was done?).  Don't install the grip screw until you're ready for final assembly, then measure carefully.  I've seen kits with grip screws from 3/4 to 1 1/4 long.  I recommend the 3/4 long screw.  If your screw is too long, it will collect aluminum in the new threads that it "cuts" and when you try to remove it, it will gall, and block up the threads in the screw, and as you remove it, it will strip out the remaining threads.  I learned this lesson the hard way ONE TIME, got it fixed, and switched to the shorter screw.

If  you get a plain silver one, clean it out well.  It has lots of grit in it, especially the holes and cavity.  If you KG GunKote it, no more than two coats, or your tolerances will be AFU.  It will probably chip off of all of the sharp angles on the lower.

I hope that this helps.

Tom

The metal, treatment, and the finish means a lot.

Not quite what they would seem. Tom, thanks for an outstanding review. This helped a lot!
Thanks - Jim