I just purchased my 1st Ar15, it is a Colt Match #6551 with 20" barrell and carry handle.  I know that I want to put a 6 position stock on it but not sure about what else.  I will mainly use it to target shoot with, but this is my only rifle for now so if I get the chance to go hunting, this will be the gun for now!  I don't know if I should put a scope or red dot.  I would love to have a "nice" optic now, but I just paid for the rifle so the funds are low.  I will get something "nice" later but for now I need to stay at $100 or below for my optics.  Any upgrade suggestions would be very helpful.   Also will most after-market parts fit on my Colt?  Thanks in advance for the help!!

My advice: shoot it your rifle first.  You can't know what optics and other things will fit your needs until you've gotten to know your rifle - and you can't know your rifle until you send some lead downrange.

Get some ammo and some magazines first.  Wait a while for that other stuff.

Bullets and targets

I received 5 Colt 30 round mags and 600 rounds of ammo with the rifle, and I'm going to the range either tomorrow or Saturday!

sounds like you are on your way.  i think you will find at 100 yds irons are just fine.
shame you didn't get a flat top.

You need to let me borrow that rifle, so I can "sight it in" for you.  

Just enjoy it as it is.  You'll start to figure out the upgrades you want the more you play with it.

usgi mags and ammo

You need at least 3 or 4 more ARs

I received 5 Colt 30 round mags and 600 rounds of ammo with the rifle, and I'm going to the range either tomorrow or Saturday!

I'd buy at least 10 USGI mags and a case of ammo.  I wouldn't change the stock on a 20" rifle.  I would consider a Trijicon ACOG if you want to add something to your rifle.  Just my .02

Jay

Don't forget to follow the Break-in Procedures! You'll need your cleaning kit with a good lead/copper remover. Read your directions on how to do the procedures. I cleaned my first rifle wrong and didn't know it until later. I always pushed the cleaning rod through then pulled it back with the brush on it rather than pulling the brush off before pulling the rod back through it.

I'm going to be breaking in a new Pony tomorrow also ;) Good luck at the range and HAVE FUN!

Semper Fi

A               M                     M                      O                !!!!!!!!!!!!!!!!!!!!!!!!!!!!!