I am new to the forum, and do not own an AR yet.  I have plenty of experience shooting them from the Army Infantry.   Also have a lot of friends with them, as I am a LEO, and a lot of officers have them.  I can shoot them, tear them down and clean them, and put them back together.  That is about the extent of my skills so far.

First, from what I have read so far, most uppers and lowers will fit, although some may need minor adjustments, and work together fine.  Kind of like a 1911.  Am I understanding this?

Next, you can buy a rifle several ways.....
A complete rifle
An upper and lower
Stripped upper and lowers with parts kits
I know that the complete rifle will probably be the most expensive way to go.  How much $$ can be saved buying a complete rifle as opposed to upper and lower, as opposed to stripped upper and lowers with parts kits?  Just would like a basic comparison to see where the differences are.

Next, barrel twists and lenghts.  Basically speaking, is 1:7 bette rthan 1:6, or better than 1:8 on the same lenght barrel?
Also, for my purposes, a 16" or 18" barrel would be best.  What twist works best with this barrel lenght?

As far as a couple option go, what is preferred?  I assume back-up iron sights, as posted on here.  Do all styles come with the military-style adjustable elevation and windage knobs?  

What is preferred as far as the carrying handle goes?  Do they both mount scopes?

From what I read, RRA and DPMS are reputible manufacturers.  Would I be a fool to purchase say, Bushmaster or Colt parts when others are availoable for less?  Are they all pretty much equal parts?

Thanks for taking the time to answer a few questions.  I have many handguns, but want to start exploring with ARs, and have no experience building or assembling.
Rob

Quoted: First, from what I have read so far, most uppers and lowers will fit, although some may need minor adjustments, and work together fine.  Kind of like a 1911.  Am I understanding this?

if you ignore Colt, pretty much every lower and upper will just swap right on. Colt has a problem selling standard uppers and lowers to the general public, so they have used at various times pins that are not what everyone else uses.

Next, you can buy a rifle several ways..... A complete rifle An upper and lower Stripped upper and lowers with parts kits I know that the complete rifle will probably be the most expensive way to go.

It can be. You can get out of paying the excise tax by building from parts. You can also get a gun that is exactly what you want. As a newbie, I suggest buying a complete rifle for your first one to sidestep all of the "my homebuilt doesn't run right" problems.

How much $$ can be saved buying a complete rifle as opposed to upper and lower, as opposed to stripped upper and lowers with parts kits?  Just would like a basic comparison to see where the differences are.

If your time has no value, you can certainly save quite a bit building from parts. I choose to "build" my rifles by buying them complete, or buying an upper and a lower.

Next, barrel twists and lenghts.  Basically speaking, is 1:7 bette rthan 1:6, or better than 1:8 on the same lenght barrel?

better how? in general, the right twist is a matter of the velocity and mass of the projectile you're using. To put it another way, you could pick a load (say, SS109 or similar) and find the "best" twist for it. Ignoring outliers like beanfield rifles, 1:9 works well for most commercial ammo.

Also, for my purposes, a 16" or 18" barrel would be best.  What twist works best with this barrel lenght?

again, it's more a function of what you want to use the rifle for. I suggest you find some people that have ARs in configurations like the ones you're considering and try them out. No point buying a kickass $800 upper if you're going to be shooting Wolf at 25 yards. YMMV.

As far as a couple option go, what is preferred?  I assume back-up iron sights, as posted on here.  Do all styles come with the military-style adjustable elevation and windage knobs?

There are two main types of upper - with and without carry handle. Those without a carry handle usually don't come with a rear sight. You'll need a BUIS if you wish for that option. Personally, I use reflex optics and don't keep the iron sights.

What is preferred as far as the carrying handle goes?  Do they both mount scopes?

Mounting optics on a carry handle is problematic, as you end up with two cheek welds to learn. You can get a cantilever mount from several manufacturers to get around this. It's more a training issue. I prefer not using carry handle mounted optics. That said, I have a rifle in just that configuration. I just don't prefer it.

From what I read, RRA and DPMS are reputible manufacturers.  Would I be a fool to purchase say, Bushmaster or Colt parts when others are availoable for less?  Are they all pretty much equal parts?

ABCDR - Armalite, Bushmaster, Colt, DPMS, RRA. Stick with any of those and you're fine. Everything else is a religious argument I'm not touching.

Thanks for taking the time to answer a few questions.  I have many handguns, but want to start exploring with ARs, and have no experience building or assembling. Rob

HTH

Rob, welcome to AR-15.COM. I too am new to the site and new to AR's, so I won't attempt to answer your questions as I'm no expert and have very little expierience.

The best thing I can recommend is to do some reading here on the board (check the "tacked" items).

YOU CAN LEARN ALOT FROM READING THE OLD POSTS. (you will hear this from others who post after me)

There are some (lots) of VERY knowledgeable folks here on this site, reading what they have to say really helps.

Happy Holidays

Gene

Good comments above, although IMO a 1/7 twist barrel will allow the use of the heavier rounds now preferred by our SF forces and sticking to the A3 flatop upper will allow you options for optics that the A1 and A2 style uppers simply can't touch without additional weight considerations.

Good luck and welcome aboard,

Mike

Mr Jones info is very good. I'll give you another perspective or at least mine

Quoted: I First, from what I have read so far, most uppers and lowers will fit, although some may need minor adjustments, and work together fine.  Kind of like a 1911.  Am I understanding this? YES Next, you can buy a rifle several ways..... A complete rifle An upper and lower Stripped upper and lowers with parts kits I know that the complete rifle will probably be the most expensive way to go.  How much $$ can be saved buying a complete rifle as opposed to upper and lower, as opposed to stripped upper and lowers with parts kits?  Just would like a basic comparison to see where the differences are. You do not always save by assembling one versus factory rifles. Go factory rifle for a first AR15. Next, barrel twists and lengths.  Basically speaking, is 1:7 better than 1:6, or better than 1:8 on the same length barrel? Also, for my purposes, a 16" or 18" barrel would be best.  What twist works best with this barrel length? The most popular - for good reason - is the 16" barrel with a 1/7 twist. This will enable you to fire virtually all 5.56/.223 rounds including the heavier ones. Not aware of a 1/6 twist. As far as a couple option go, what is preferred?  I assume back-up iron sights, as posted on here.  Do all styles come with the military-style adjustable elevation and windage knobs?   No. Not all include both windage and elevation. Most popular choices are Troy, KAC, and ARMS. There is a great thread on the subject in the AR15- optics forum What is preferred as far as the carrying handle goes?  Do they both mount scopes? I suggest getting a factory gun in A3 - flat top configuration and comes with a detachable carry handle. One of the primary advantages of a flat top is not having to mount optics on the handle. Therefore get a mount designed for flat tops. LaRue is one of the leaders here although there are many. From what I read, RRA and DPMS are reputable manufacturers.  Would I be a fool to purchase say, Bushmaster or Colt parts when others are available for less?  Are they all pretty much equal parts? No they are not equal. Just as GM, Ford, and Toyota and Lexus are not the same neither are DPMS and Colt. DPMS is is budget manufacturer that makes OK stuff but not on the level of a Colt. Colt and Bushmaster are seen as the top 2, with Colt demonstrably better. Thanks for taking the time to answer a few questions.  I have many handguns, but want to start exploring with ARs, and have no experience building or assembling. Rob

Get yourself either the Bushmaster Patrolman's Carbine in A3 configuration or the Colt LE6920 or LE6721, and you will have the best off the rack AR15 made.

Welcome aboard , Pharley and good luck with your new rig!

Welcome to the addiction

An excuse for some gun pr0n!!! woot!
Since you are LEO (lucky Dog) I would buy an AR-15 ready to go out of the box.  You showed interest in a 16" Barrel, A3 flattop with BUIS and scope options.  You want quality, good fit, nice finish, etc. etc.

An LMT Defender  :: drool ::

Quoted: An excuse for some gun pr0n!!! woot! Since you are LEO (lucky Dog) I would buy an AR-15 ready to go out of the box.  You showed interest in a 16" Barrel, A3 flattop with BUIS and scope options.  You want quality, good fit, nice finish, etc. etc. An LMT Defender  :: drool :: www.shoppekeeper.com/lewismachine_catalog/albums/products/defender_cqb_sm_2_001.jpg

Yep, may as well jump right to one of the top rungs of the ladder!!

Welcome to the site!

www.ammo-oracle.com--ammo and twist ideas (i'd lean a little to the 1-7 myself)

building will save you more $$$s (which you will probably put into mods and accessories anyways...) if you build more than 1 (usually); the 18in would be better if you require more velocity or a tad more range shooting, but overall, i would stick w/ the 16in

what are your uses for the AR? for most, the 16in will work for most jobs (expecially considering the limits/utility of the 5.56)

BUIS and optics on a flatop (leave out the carry handle--its just in the way, nothing a lower mounted optic and BUIS cant fix, and no one ever uses the carry handle)
some brands have the mil-style windage/elevation knobs, some are just peeps....

RRA and DPMS are reputable brands (i lean to the RRA b/c thier stuff is more black, while DPMS is more of a dark grey, but its all cosmetic); Bushy and colt are also good, but parts are more expensive, but quality is overall the same (also, check out LMT and CMT for quality parts for less $$$s)

check out the "build it yourself" forum www.ar15.com/forums/forum.html?b=3&f=4--the first half dozen tacted threads will help out a lot

good luck