Hey guys, I'm new to the site and have been contemplating building my own AR for quite some time. Just got a few questions that hoping some of you can answer.

1) Are all AR parts compatible or do I need a specific manufacture or brand? I'm looking to buy certain parts/accessories to my liking.

2) If I get an upper receiver, say an AO Precision, will a Del-Ton lower receiver work together?

3) Any brand or manufactures or website you guys recommend to continue research to possible make my final decision on which to build?

Thanks for the help guys

As long as the parts are Mil Spec, they will be pretty much mix and matchable, including the uppers and lowers..

 

What Dennis said ... some lowers and uppers may not match up perfectly... some gaps....  can google that though.

Certain billet uppers will not mate well to certain free float hand guards or match up well with other brands of billet lowers. From what I've seen the best looking billet lowers are mated to the same brand billet upper.  I have a billet lower and a mil-spec forged upper by another brand that looks really good. It was my first build and being new to ARs I think I just got lucky.

As far as suppliers - All of the companies at the top of this site support the site and are reputable.

dano:  As the other mentioned, so long as you are dealing with milspec parts, they usually mix and match just fine.  However, I suggest you stick to name brands for all components and buy a matched set of receivers, i.e., from the same maker.  In my part of the country, Aero Precision and Mega are considered first rate.  Shop around and look for brands that sponsor arfcom like Delton, MI, Stag, CMMG, et al.  FYI, Mega makes Rainier's receivers.  When in doubt, check the internet for reviews by arfcomers, some brands have a spotty record, but the best brands like Stag, Aero Precision, Vltor, and Noveske are worth the extra effort and expense.  Cutting corners and buying no-name parts at gun shows is false economy, IMO.  

BTW, the barrel is the key component for accuracy.  For the 5.56 caliber, I really like my Green Mountain barrel.  Its a 20", 1in8 twist, chrome lined, govt profile and it cost less than $200 shipped.  With my handloads (52 gr Matchkings over Benchmark powder) its routinely puts 10 rounds into less than an inch at 100 yards from a rest. good luck and keep your questions coming - CW

http://www.gmriflebarrel.com/ar-15-m16-m4-rifle-barrels/

Alright thanks for the replies guys. I've been looking at lower receivers to purchase to start this build. I narrowed it down to two, an RGUNS GSLROD or a Stag Arms, both stripped. One question I have is the RGUNs is Mil-Spec 8625, does the "8625" mean anything in general? Also both lowers are .223/5.56 NATO, is there a specific lower parts kit that will work for either of these brands, and when do I have to make the final decision on the caliber? Right now i'm leaning towards .223, but i'm sure i'll switch it up as this process moves forward.

Thanks in advance guys, you guys are a lot of help. I really do appreciate it.

The difference is in the chamber, they both have the same caliber. You can safely shoot .223 through a 5.56 chamber, but shooting 5.56 through a .223 chamber isn't a very good idea. If it were me, I'd get a barrel chambered for 5.56 or a 'Wylde' chamber. For your lower, ' .223/5.56 NATO ' is probably just the roll mark, which usually won't affect what upper you can run on it.

Also another question after looking at my lowers and uppers I settle with DPMS. Do all AR's have to use a Gas block? Is there a certain upper, lower, barrel I'd have to look into to avoid the gas block?

The gas block is essential to the semiautomatic of the ar15 platform.  Unless you want a single shot ar then you need a gas block.

1) if the parts are to spec, they should be interchangeable.you should try to do matched uppers and lowers for the best color match, but most are fully interchangeable.
2) yes, it should work
3) I use Spikes Tactical, Battle Arms Development, Strike Industries, Seekins Precision, etc. Primary Arms carries a bunch of nice stuff with fast shipping.  Rainier Arms is nice also. You can truly change nearly everything to suit you personally.

Most do yes. .22LR barrels do not.

The gas block sizes may vary depending on your barrel.  The most common is .750 on most non heavy profile or non pencil barrels.

When you are looking at barrels they will state what the diameter of the barrel is at the gas port, this will be the gas block size you are looking for. They will also tell you what gas system it uses, rifle, mid, carbine or pistol. This will correlate with what gas tube length you need.
Before you ask the common question, these lengths have nothing to do with your stock designation. It is only describing the gas port placement.

Invest in a decent upper and lower so the anodize is the same color.
Granted they might be mismatched regardless, however you can likly find a better matching setup sating within the same brand.

I think mega has the best anodize around.

Nortech Uppers are cute too :0

Op where in pa are you? If your close your welcome to check out my ars to figure out what you want to build. I'm happy to give you a hand too

OP

http://www.ar15.com/forums/t_3_4/605350_Important_Threads__Check_Here_First.html

Scottdale Pa, 45 min outside of Pittsburgh