Hello!

So i'm not new to the AR platform by any means, but I have never tried to put one together before. Ive got a stripped lower that I had originally planned to sell, but i think it might look better as a complete rifle in my safe next to my other AR. Ive been shoppin around for parts for a while, and price is a huge factor. Here are the questions i've got.

1. My current AR has a carbine length gas system. I think that, if possible, id like to make this new one have a mid length system. If i get this LPK:
http://palmettostatearmory.com/index.php/p-tac-lower-build-kit.html ,  will that buffer tube and buffer work with a mid length gas system? I was probably going to go with a complete upper like this:
http://palmettostatearmory.com/index.php/psa-16-mid-length-cl-mp-premium-upper.html.  Would these work together, or should i just stick with another carbine?

2. Whats the difference between a full auto, M16 and regular BCG?

3. Whats the advantage (besides looking pretty) of a nickel boron BCG?

4. If i go with the options in question 1, what specific tools will i need to assemble this rifle? I know for sure that i'll need a castle nut wrench.

5. Please tell me about this upper: http://palmettostatearmory.com/index.php/psa-14-7-hf-m4a1-upper.html
   specifically, why is it important that it is unpinned, and is this legal without a stamp, or does the flash hider make it legal? I like the idea of a shorter rifle for home defense. And WTF does CHF stand for?

Sorry for being so clueless, but I never thought that i would want/need more than one AR. I cant even afford to shoot the one I have as much as I would like. Maybe I should take the cash i've got stashed and buy ammo instead.... I appreciate the help!

1. Yes that buffer tube and buffer should work with a middy gas system.  If you're worried about cycling issues, those usually come from out-of-spec gas ports, at least in my experience.

2. Full auto & M16 carriers are one and the same.  There is a little more meat on the M16 carrier as opposed to a semi carrier.  Some say it helps dampen recoil having a little extra weight on the carrier.



3. I hear that nickel boron bcgs are easier to clean.  I've never used them, never felt a need.

4. If you go with the already-completed upper, you will need that castle nut wrench plus everything to assemble the lower receiver, namely, a screwdriver and roll pin punches.  I've never used roll pin punches and prefer to use vicegrips with taped jaws, but that's just me.  Refer to FALARAK'S build guide in the BIY forum if you'd like more info on how to do this, it's the easiest way to assemble a lower IMO.

If you don't go with the completed upper and instead want to convert your carbine length to a midlength, then you'll need of course the midlength barrel and gas tube plus tools in order to remove your barrel from your existing upper receiver.  These would be a barrel nut wrench, upper receiver vise block, torque wrench, and a sturdy bench vise.  Upper receiver assembly/disassembly instructions are also included in FALARAK's guide above.

5. The upper listed here is NOT legal in that configuration as a rifle.  The flash hider is most likely unpinned to allow the buyer the option to replace the standard A2 birdcage hider with a muzzle device of his/her choosing, but it would need to be pinned (or otherwise permanently attached) in order to be legal AS A RIFLE.  Of course, you could also do a pistol build with this upper and not worry about the pinning, but of course that will limit your stock options.

CHF stands for Cold Hammer Forging, a process of making barrels by hammering a blank around a mandrel to achieve the rifling pattern, as opposed to reaming the bore of the blank to produce the rifling, or so I understand.  CHF barrels, including those made by FN (as is the case here) are well-known for their longevity and resistance to wear, though some say they're not as accurate as cut-rifled barrels.  I've never had an accuracy issue with FN's CHF barrels and prefer them in my builds.  These barrels are routinely offered by Palmetto State on sale, and IMO one of the best values in the entire market.


This hobby of ours is indeed addictive.  Get down with the sickness.

1. They would work together
2. Non FA BCG's would have some material omitted at the end which would otherwise be used to trip a FA sear on an M16
3. Nickel boron is supposed to have self lubricating properties
4. Off the top of my head I can think of roll pin punches for the bolt catch and a long flat head screwdriver for the grip
5. The longer flash hider would've made it legal had it been pinned to the barrel. In its current unpinned configuration it's only legal for use on a registered short barreled rifle or a pistol setup. CHF stands for cold hammer forged.

EDIT: LOL the guy above beat me to it :P

Thanks for the TL;DR version

Yea you probably made that post as I was typing mine up

M16 BCG is a.k.a. FA BCG. Semi-Auto BCGs are not standardized and can have any amount of material in the bottom from nothing, to just a little less than an FA carrier.





Nickel-Boron, Ion Bond, Chromed and other treatments are meant to make the BCG easier to clean. Though with lots of lube you don't really need to clean it much anyway.