I can do $50+shipping for you guys. :D (yes, only you cheapass 308ar.com bastards). <lmao> <laughs>
I'll have to ship to an FFL though, unless you wanna drive out and get it direct from me. :D
Some company in China is probably making knockoffs of popular handguards. There's a bunch out there for the AR-15/M4 so I assume that sooner or later the 308 versions will turn up, if they don't already exist. That would be the easiest path if you can find them.
Not much. The thickness of that part should be 0.1" per spec so your're removing about 3% of the effective thickness.
Seen pics of Tungsten. It's sexy. I have it on my to-do list for one of the custom builds for one of the forum members.
Only on the serial number (if any) plus any NFA specific markings. Homebuilds based off an unmarked 80% lower are not required to have any markings at all and if added later can be done with the owner's discretion.
Being from a manufacturing background, you've probably seen things slip through QC. Doesn't mean they're all bad, all it takes is one piece to get out there to the wrong hands. More important is how the company deals with the problem. :D
Set screw is what I use on all my gas blocks. I don't use adjustables, and just simply clean the rifle on a regular basis.
...come to think of it, I oughtta be making adjustable gas blocks...
That sand should be fine.
Removing the engraving depends on how deep the engraving is. The minimum 0.003" depth requirement by the ATF is already hard to sandblast off and most manufacturers willl engrave deeper than that to be safe from ATF scrutiny. Just as a benchmark, our automotive stuff is engraved to 0.001" depth and it's still not easy to sandblast off unless you hold it there for a good amount of time.
Just going by the training manual, page 6.
"Hard anodizing does not need to be removed if it withstands 3-5 seconds of blasting at normal blast pressure (80-100 psi) in one location without coming off the part."
Everything I've done so far stripped easily to bare metal. :)
Blasting specific sand? Aluminum oxide, garnet, ground silica works best. BTW, you don't need to strip it completely. Enough to scuff up the hard anodize is sufficient.
That, and the shiny/reflective surface doesn't help either. Compare with a phosphated BCG in flat black and it's harder to tell.
....and it does look pretty.
Take it with a grain of salt. There's always a ton of shît-talking on the interwebz so ask around before you rush to judgement, and it looks like Tom has set you straight. :)
No, the carbine buffer tube is not compatible with either the PRS or the Luth-AR stock. You'll need to change out your entire buffer tube assembly (i.e. including buffer and spring) to a rifle length setup.