I've built two doublestar lowers into great shooting rifles so far,,, and that one in the pic is my next project.
Never had a problem. You'll hear a lot of guy swearing that you should use this brand or that brand,,, blah blah,,, ...
I've built on Bushmaster, RRA, Superior and Doublestar (all stripped) lowers so far,, and I've come to the conclusion that as far as the stripped lower goes, thery're pretty much all the same. I won't use another Superior because the won't fit my Thermold mags..
But Doublestar quality is Great, I'll definately buy some more.. You can sure pay more for a different mark on the lower if you want to....
I do however like to use RRA LPK's in everything.
The accuracy is all wrapped up in the upper, and that's a whole 'nother story...