What are some good investment guns that are probably more than likely no longer made and aren't crazy expensive like a full auto M16? I recently just bought my first Colt Python as they tend to keep going up in price. What are some other guns out there for a collector?

Staying with Colt, prewar 1911's, Peacemakers 1st, 2nd and even 3rd generation, any unique revolvers they made, for instance my Colt Diamondback in 22lr, is gone up 400% in value since I bought it 25 years ago.

machine guns shouldn't be investments.

Firearms in general are shit investments

Yep it's not like every C&R gun ever imported hasn't double or tripled in value later down the road.

M1 Garands.  You should be buying your allotment from the CMP until they run out.

Good advise. Lugers & P.38's have served me well, but the trick is knowing what you are buying, and finding it at a good price to start with.
In the case of Lugers, it's getting harder and harder to find good ones at decent prices. Just about everybody is asking top dollar for them now, even for crappy mis-matched ones.
P.38's have likewise gone up a great deal in the last couple years.
WW2 is getting farther and farther away, and another aspect is, as the older generations pass away (WW2 vet's KIDS even), the direct connection aspect is going to start appearing, which is two fold:
one:
Demand will tank as younger generations begin to just see these as "old guns", So prices may fall, which is bad for an investment piece.
and two:
Inheritors may dump the pistols at cheap prices because they see them as just "old guns". Which would be good should you find one.
Most likely though, demand will fall some, and Jimbo-BillyBob will remember Grandpa's old natzee pistol is worth more than his house, and so prices will go higher.
This is going to be true for any WW2 piece. Mum'ed Arisaka rifles are going for almost three times what they were just a few years ago when they could hardly be given away.
It's all supply and demand baby!
Don't invest in AR-15 type rifles, or anything which is still in mass production.

Shootable, almost affordable "collector" guns include 70s Smith & Wesson revolvers, and pre-Freedom Group Marlin lever .22s.  As noted, guns are not the sort of thing that generally makes a good investment.  Guns are fundamentally tools.

Good luck!

Older pinned and recessed Smith & Wesson Revolvers
Colt Snake Guns (anaconda, Python, boa, diamondback etc)
Belgium Browning Superposed shotguns
Original Pre-1964 Winchester Model 70's

Lots of them here .....

Better know what your doing, though.

fan boy anything 1 glocks, prelock S&W, Walther p1-p99- esp first editions or go big & get into olympias, OSP,GSP SSP

older C&Rs If you want some old rolling blocks or trapdoors IM me. hell google chaffee rece(reese) ward burton, Remington keene, Winchester hotchkiss

You want to go big get into colt woodsman targets man ect.  

there are other snake guns - the viper, boa, king cobra, cobra, anaconda

that ought to wreck a budget or two.

So C&R is a believable exception. When you tripled your money in $99 SKS' from 1980 to 2007, how did the S&P 500 do?

 
It went up about 15x, but you are cherry picking the dates.  It did drop about 50% from October 2007 to March 2009.


 

so 1980 to 2015
I'm just saying, guns as an investment aren't GREAT.

Pre '64 Winchester Model 70.  Winchester Model 12 Pump, especially the solid rib 3" Heavy Duck version.  Remington 725 (what the 700 should have been).  Older Sako "L" series bolt guns.  Browning Superposed O/U.  Remington 541S .22LR bolt action.  Post war, pre 80's Browning FN Hi Powers. These are a few reasonably priced collectables.

The rare "key" guns in a series. In U.S. military collecting, these would be things like gas-trap Garands, unaltered M1894 Krags (with full-length cleaning rods), Pedersen Devices, Singer or US&S M1911A1's, rare M1 Carbine manufacturers, etc. These are already super expensive but they're going to become even more so.

Don't forget to correct for inflation...

I'll still stand by my statement that guns should generally not be used as an investment tool. And you're doing a diservice to fellow Americans by using a finite number of transferable machine guns as investments