I am entering the realm of Full Auto NFA.
having gone to the initial gateway drug of AR Pistols with braces and then of course to suppressors (now 7 in total)
the next logical step in this progression is full auto.
I have more than 30 years experience with full auto on the MIL side. I have no first hand knowledge of civilian FA other than what I red in the popular comic books (gun Mags) there is a lot out there to learn and I am not bashful about learning, especially if its form someone else mistake (cheaper for me) And there is some urban legend to deal with too.

My plan is to purchase an M16 style platform with which to add a Tactical Innovations 22 Upper and a 9mm upper.
as you well know there are lots of choices in M16 platforms manufacturer wise to choose form.
This is where I need some insight.
I want an A1  style lower  
Push pin style, no screws.
upper doesn't matter that much since I will be "accessorizing" heavily.

The Colts appear to be the gold standard. (non SP1) and the most expensive. Price is not the main consideration but it is one none the less.
1. I want the most bang for my bucks and interested in how the Colt and others appreciate over the course of this investment. say , what you think grows in value the most over a 10 year period.
for example, if I spend 20K for a Sendra or spend 27K for a colt.. In 10 years will they each have increased in value proportionally or will the Colt outstrip the lesser brands.
2. Colt being considered #1, what order would you place the following?
I understand some of these were just conversions of other manufacturers  lowers.
Sendra
PWA
Oly
Wilson
Small Arms Weaponry
SWD

who used forged lowers.
3. forged versus cast lowers , my feeling is forged is better, more durable, even if the lower doesn't really get stressed.
4. highest rated and most honest dealers out there?
5. anyone have experience running 9mm conversion on their FA lower? what brand?
6. what considerations in looking at FA M16 platforms to be careful of?
7. I see prices from 18K up. I see quite a divergence in Colt pricing. some dealer seem to think more highly of their Colt inventory than others do. so, what are reasonable prices to pay for the brands listed previously?
8. any other advice or considerations I should be aware of or be thinking about?

any information is appreciated.

Raised fence around the button is not A2, it's an A1 feature. A2 is reinforced pivot pin and receiver extension boss, primarily.

May ETA later as I think about things.

ETA1: Non-Colt is better bang for buck, unless you overpay for the non-Colt. Oly made PWA, and other than Sendra, almost no-one made their own lowers.

Forged is better, but Essential Arms were the gold standard of cast lowers - reputedly cast for them by Ruger. Nothing wrong with an EA J-15 other than being ugly.

I ran 9mm on both my posties and some transferrables with a lightning link, using the KNS re-enforcer. I've run Colt pattern and Olympic arms 9mm systems full auto with great success and satisfaction.

Colt pricing varies by features and rarity. Both do the same thing, but rare originals will run you more due to rarity.

thanks. typo, meant A1

Unless I missed something you will need to engineer your own sear trip solution for a tac innovations upper.

1. RLL give you the best bang for your bucks as they are the cheapest way to legally shoot full auto via a M16/AR15 platform. A SP1 or non-colt RR is your next cheapest, then your Colt M16 A1s, then your A2s, and finally RDIAS. Each options has different advantages and disadvantages that I wont get into here. Personally I went with a Non-colt as I was on a tight budget. A Colt M16 A1 or A1 would have been awesome but I was already stretching for the Non-colt. RLL require a modified mil-spec burst trigger to be able to fire safe/semi/auto and I really wanted a Geissele SSF trigger so that was a dealer breaker for me. Also RLL have paddles, potential timing issues, require an SP1 BCG and as a new MG owner I just wanted the plug and play of a RR.

2. Colt is the gold standard. After that they are pretty much all the same. Some say Oly is best, others say Senda, SAW, its all personal preference IMO . I went with an Oly, their A1 style lowers look very similar to a Colt and I liked that it was Marked "M16" as the model and "Safe/Semi/Auto" and it had a full fence and push pins (Colt SP1s just dont look like an M16 to me)

3. Forged lowers are stronger than cast. E.A and Bushmaster are the two that pop into my head as casts lowers. They are easy to spot as they will often have raised letters instead of engraved or stamped. In all reality they are probably fine but out of all of the M16 options forged RR tend to be the red headed step child that no one really wants unless its a crazy good deal.

4. Ive bought all mine from frank at Midwest tactical.
http://www.atfmachinegun.com

Ruben also has a solid reputation
http://dealernfa.com

I would stick with a dealer for your first few purchases as there are scammers out there and I wouldn't risk getting ripped off $20k just to save a $1,000. Pay the premium for the peace of mind.

Websites to watch for good deals on machine guns:
http://www.sturmgewehr.com
https://www.rockislandauction.com/
http://www.autoweapons.com
http://www.impactguns.com
http://www.subguns.com
http://www.capitolarmory.com/class-3-nfa/machine-guns.html
http://www.onlythebestfirearms.com
http://www.davidspiwak.com
http://www.gunbroker.com
http://www.nfasales.com
https://www.machineguncentral.com
https://www.machineguncentral.com/default.aspx
http://mtmmfg.com
http://www.classiiidealers.com/
http://www.westernfirearms.com/
http://www.collectorsfirearms.com/class-iii-full-auto/
http://www.urban-armory.com/
http://www.ar15.com/forums/f_7/118_NFA_Firearms_andamp__Parts.html

Website that tracks machine gun values:
http://www.machinegunpriceguide.com/

5. There was a point in time when it was recommended to not run 9mm in a RR due to wear and tear of the blow back action. I think a lot of the issues that caused the wear on the lower have been revised and it seems to be acceptable as of lately. Im not at expert on this issues as I use a M11/9 as my dedicated subgun.

6. Makes sure the lower is in spec and that uppers fit properly, this is a common issue for non-colts. Make sure you try your upper on it, not just the one that comes with it as some people modify uppers to fit.  If you have fitment or spec issues most can be resolved. USAnodizing does gun smithing and will reanodize a RR. I paid $500 to have the upper shelf and rear radius milled down to spec on my oly lower, fits great and looks like a brand new M16.

7. Dealers use different strategies. Some sell low and do high volume of sales while others jack up the prices, only sell a few but when they do they make a better return. And others dont own the firearms, they just connect the seller with buyer so prices are not under their control. Prices are in a bit of a slump so its a decent time to buy.

M16 Market Data
Transferable M16 machine guns and estimated market values:
RLL $15-17k
RDIAS $30-35k
RR Non-Colt Cast AR15 Conversion $17-19k
RR Non-Colt AR15 Conversion $18-20k
RR Colt AR15 SP1 Conversion $18-20k
RR Colt AR15 614 $22-25k
RR Colt M16 $21-25k
RR Colt M16A1 $23-27k
RR Colt M16A2 $27-32k
RR Colt M16A2 Commando $30-35k (Marked "Auto" instead of "Burst")

8. Dont spend more money than you are willing to loose. MGs have gone up in value since 1986 but there is no guarantee it will last.  All it takes is one nut job to ruin the fun for everyone. If the Vegas shooter had used a RR instead of a bump stock we probably wouldnt be having this conversation right now. I used disposable income to buy my MGs, if they go up thats wonderful! If they get banned and I loose all that value, oh well, it was a fun ride while it lasted, and at least I cant tell people I owned a MGs. And regardless of the price I will likely never sell them and am plan to pass them on to my son when I'm old and grey.

Best of luck on your purchase and be sure to post lots of pictures when you get it.

3dprintit

Well,
I took the plunge. I put a deposit on a Colt M16, transition model. in that I mean its marked M16 but has the A1 raised fence around the magazine release.
From  Midwest Tactical.
now the wait begins.

next acquisition will be Tactical Innovations 22 upper.

I have a Tac Sol .22 upper and it does not work well on my M16.   Gat a cmmg dedicated barrel and bolt assembly and build your upper yourself.   I used a Colt A1 upper with the 4.2” barrel.  It’s a buzz saw.  Get the trip and weight kit also

yhea i would go cmmg/rtb for a .22 upper, you will need the sear trip and anti bounce weight

I wasn’t able to get my CMMG 4.5” rimfire upper to run the first time out. I haven’t revisited. Having too much fun with the 9mm RDB and Endo mags.

I've heard enough and seen enough about 9mm ARs being hard on pins, even though some say bolt ramping will alleviate the problem.

I've decided not to chance it on an expensive transferable lower but YMMV.

When you say pins talking about the hammer pin not the pivot pins I have a cast sendra arms lower looking at cheaper fun with some pistol conversions like 45apc, and 10mm possibly.

Regarding full auto 9mm on the M16 platform see my post here:
https://www.ar15.com/forums/AR-15/Most-reliable-9mm-upper-conversion-that-fits-an-AR15-receiver-/15-750573/

Basically, I have run straight blowback 9mm configurations on a RR many hears ago and have egged out the hammer pin hole on a lower and seen too many issues doing so and would never do it again.

I wouldn't hesitate to put a CMMG RDB 9mm upper on a transferrable lower however, it is hit or miss whether or not you may encounter ejector spring failures.  I have all this documented on my site below:
http://www.c3junkie.com/?page_id=280

Pictured below is a 5.56 12.5 Mid gas upper w/ Brevis Ultra II suppressor.  Ported to only run with that suppressor mounted.
Below that is my CMMG RDB w/ a fixed ejector installed, MEAN Arms Endomag insert in the windowed PMAG....etc...


As mentioned, in the first link, if you aren't in a hurry, I would wait to see if the new MEAN Arms roller delayed upper is GTG.  If so, I'd go for that.

I was absolutely ready to get a CMMG 9mm upper but then waited at the last second when I heard about the Mean Arms Upper.
@amphibian
Has anyone from Mean contacted you about letting you demo one of their uppers? If anyone would be a good tester you would certainly fit the bill. You will certainly done us all a world of good in tinkering with these uppers and helping folks get set up. I absolutely want to see what that new uppers going to do. My Olympic M16 is waiting

Nah, I wish they would let me demo one of their uppers.  I'm sure I'll break down and buy one of their 10.5" uppers when available and not wait for the BBL/BCG/CH kits to come out later.
Oh, I also have this thread discussing it here why I think it will be the ultimate setup: https://www.ar15.com/forums/ar-15/The-ultimate-9mm-NON-straight-blow-back-AR-M16-MEAN-Arms-roller-delayed-system-related-/15-748519/?r=8039544&page=1&anc=8039544#i8039544

I hope they release a 40 round Endomag soon as well...I've been told they are working on it.