I am new to this forum , and know nothing about rifle.  I did try to read from this forum and noted down some choices, but still have many questions.

AR15 or AR10 - What's the difference?
Below are some models that I narrowed down:
BusMaster XM15e2s
Armalite AR-10 T .308 or Armalite M15A2 .223
Professional Ordnance Carbon 15 Model 97S
RRA - What model please

What features does a preban have over post ban?
What caliber should I get?  What're its advantages?  Can I exchange mags between 2 different makes of AR of the same caliber?
Thank you so much!

If you are new to rifles I'd start with the 223 Remington caliber. The ammo is cheap, the rifles are accurate, and they don't recoil much. I like the Bushmaster rifles. The 308 is a heavier, harder kicking caliber.

LOL That was so funny I almost laughed out of my chair.

Quoted: I am new to this forum , and know nothing about rifle.  I did try to read from this forum and noted down some choices, but still have many questions.

AR15 or AR10 - What's the difference?

An AR15 is chambered in .223/5.56mm while the AR10 is chambered in .308/7.62mm

Below are some models that I narrowed down: BusMaster XM15e2s Armalite AR-10 T .308 or Armalite M15A2 .223 Professional Ordnance Carbon 15 Model 97S RRA - What model please

Think "ABC," Armalite, Bushmaster, and Colt. You can't go wrong with these.

What features does a preban have over post ban?

Prebans were rifle/carbine made before the September 1994 "Assault Weapon Ban."  They are Semi Automatic weapons that can suport a detatchacble high capacity magazine and have a telescoping buttstock, pistol grip, Bayonet Lug, and/or a flash supressor or threaded barrel that can support a flash supressor.

Post Ban AR can only have one "evil feature," which is usually the pistol grip.

What caliber should I get?

Start with the .223/5.56mm, unless you can afford an AR10.

What're its advantages?

The AR15 is a very versatile weapon, that can be configured in many different ways with many different calibers.  There is very little recoil in an AR15.  Mags for the AR15 range from 10-30 dollars or more depending on their condition and make.  Mags for the AR 10 are consdiderly higher.  .223/5.56 ammo is much cheaper than .308/7.62mm.

Can I exchange mags between 2 different makes of AR of the same caliber?

Yes

Thank you so much!

You're welcome.

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Now go read some more,

Dave S

And enjoy while learning.

Quoted: I am new to this forum , and know nothing about rifle.  I did try to read from this forum and noted down some choices, but still have many questions. AR15 or AR10 - What's the difference? Below are some models that I narrowed down: BusMaster XM15e2s Armalite AR-10 T .308 or Armalite M15A2 .223 Professional Ordnance Carbon 15 Model 97S RRA - What model please What features does a preban have over post ban? What caliber should I get?  What're its advantages?  Can I exchange mags between 2 different makes of AR of the same caliber? Thank you so much!

AR10 vs AR15: The AR10 is chambered in .308 and does NOT have a forward bolt assist.
The AR15 is chambered in .223, and has the forward bolt assist. Basically it is a miniture version of its bigger brother: the AR10.

The Ordnance Carbon 15 models have a lot of problems - stay away from them until they solve their quality control problems.

Bushmaster used to be the standard (like Colt once was). They still make a good rifle though.

Rock River makes a good rifle.

Armalite makes a very good rifle with a better finish than Bushmaster. However some people have reported problems with chambers being a little too tight..causing extraction problems with some types of ammunition.
Other than that..they make excellent rifles.

As for choosing a .308 AR10 over an AR15..well there are pros and cons..
Pro: Better knock down power at extended ranges.
Con: Mags are very expensive, spare parts are expensive and harder to find (only one supplier: Armalite) And of course if Armalite goes under....
But..the AR10 is capable of being a dual purpose Battle Rifle as well as a long range Sniper Rifle.

AR15 Advantages: Cheaper Ammo. Cheaper Mags, More parts available, more accessories available, More Gunsmiths out there who are equipped and have experience at fixing your rifle.

Pre-Ban Rifles can have Flash "hiders" and bayonet lugs. Post Bans cannot.
The Bayonet lug is pretty useless..it just turns the rifle into a "spear that can shoot".
The Flash "hider" is useful if you get into fire fight..otherwise..it is just cosmetic.

The 1994 Assault Weapons Ban should (hopefully) Sunset in 2004. So "Pre-Ban" vs. "Post-Ban" may become a thing of the past.

AR15's all accept the same mags (at least their supposed too!).

It is a good thing you are asking.

Nothing worse than getting ripped off and finding out later.

Do plenty of research before you spend your money.

Welcome to the site.

If you have to ask, you should probably go for the AR-15 in 5.56mm/0.223. Why?

Because ammo is cheap (good for learning to shoot real well),

Recoil is light (good for learning to shoot real well),

And AR-15s are cheaper than AR-10s (you can spend more on ammo up front).

Also: the AR-15 (with standard 20" barrel) is leagal as a service rifle in NRA Highpower matches. The AR-10 would have to enter as a match rifle.

Get an AR-15.

Shoot in NRA Highpower matches.

You won't regret it.

Edited to add: you can buy an AR-10 later, if you decide you want a .308 as well.

truth is, for 1000$ i would buy a pre ban. i think you should buy a post ban ar for more like 700

If you can get a preban or an AR10 for 1000 bucks, jump at it.  It's a steal.

Track down a new Bushmaster 20" barrel model. You'll be happy. Pre-bans would be nice to have but many jokers are asking $1500-$2200 for them. Is having a flash hider and a bayonet lug really worth an extra $500 or $1000? I think not. If you like the look of something on the end of the barrel, buy a muzzlebreak. Those are legal and some may actually reduce muzzleflash....though they aren't supposed to. Many will at least re-direct it.

ntunixcisco,
If you can go to a range and rent them, that's always good. But I think its extremely important to pick it up, see how it feels, balance, fit. So many different set-ups that it can drive you crazy. Also how do you want to use it?

You haven't mentioned two important distinguishing characteristics of ARs: barrel length and flat top/carrying handle models.

Look around at the various options, decide how far you are going to shoot, and whether or not you will need a scope, iron sights, or both. This will help ypu decide on the best configuration for the upper. Remember that you can add uppers in different styles, so no need to freak out over the style.

My Rock River is the RRA CAR-15 Tactical Elite (post-ban).  16" barrel, flat top, but with a rear sight mounted to the rail, A2 style butt, M4 style short round hand guards. I'm happy with it.

You guys are awesome!  Thanks for your helps and I've learned a lot more about rifles.