I'm looking to buy my first ar-15, but can't decide between a 16" carbine and 20" barrel. The two rifles I'm considering are the Bushmaster XM15E2S Shorty A3 16" and XM15E2S A3 20" Target model. I want the A3 model because I plan to startout using the iron sights, and then upgrade to optics later when I can afford it. The rifles will be used primarily for target shooting at the range. It doesn't need to be a "sniper rifle", but I'd like it to be reasonably accurate, as it makes target shooting more fun.

I have a couple of questions to help me decide:

What's the difference in accuracy between 16" and 20" barrels?

Does a compensator affect accuracy? (I'm thinking of the mini y-comp for a Bushmaster).

Thanks,
RGB3

thats the attidtude that I bought mine with and I am happys so far. the real difference between, 16 inch and 20 inch models is not nessecarily the accuracy the real difference is in the muzzle velocity. a 16 inch will be just about as accurate, but will not produce quite the muzzle velocity of a 20. personally if your only us for the rifle will be to use it for target shooting I would go with th 20 inch, for the reason, that the sights are farther apart which increases the sight plain, which in turn makes accuracy easier for the shooter. I got mine in 16 inch because I take it with me when I go camping and it is my designated home defense rifle. the muzzle break can have a destabilizing effect on the bullet which can inturn make for slightly less accuracy, or so I hear I have never noticed a difference. the main point to consider when thinking about a muzzle brake is the noise. a muzzle break diverts the gas back towards the shooter and therefore the shooter hears the sound louder.

hope this helps a little,
the good news is you have come to the right place because if you do have any questions just ask I'm sure some of the people hear with more knowledge than me will help you out.

I just bought the Bushy 16" shorty A3 and really like the way it handles.. I thought that the 20" was too front end "barrel heavy".. I looked at both at a gun show and the 20" felt awkard and unbalanced when compared to the 16. The 20, it seemed, had all its weight out front, where the 16 was balanced nicely. A scope (if you go that route) and/or a full mag would make the 20 balance better though i think.. But fluting the 20 would loose about .5 lbs (or so bushmaster says), so that would help it as well...

Got one of each...  Prefer the 20 inch for target but the 16 is more manuverable...   Buy one and add another upper later...

I have a 20" A3 and it's great. Yes it's a little heavy in the front but you will build muscles to handle it. I just got mine in January. I'm going to getI have a 20" A3 and it's great. Yes it's a little heavy in the front but you will build muscles to handle it. I just got mine in January. I'm going to get a Harris Bipod for it. I figure if its heavy they make a counter weight to put in the stock.
Muzzle break I wanted on, but these guys talked me out of it. They said makes it louder. It does I heard one. Personal choice I still like the looks. I don't know if it degrades accuracy. I also like the flash suppressors. Problem only for pre-ban according to the Bushmaster site. Get a Dewey Coated Rod or Snake Bore. If you get the rod get a Breech Rod Guide and that CLP stuff. Trust the wisdom of the people here.
a Harris Bipod for it. I figure if its heavy they make a counter weight to put in the stock.
Muzzle break I wanted on, but these guys talked me out of it. They said makes it louder. It does I heare one. Personal choice I still like the looks. I don't know if it degrades accuracy. I also like the flash supressor. Problem only for pre-ban according to the Bushmaster site. Get a Dewey Coated Rod or Snake Bore. If you get the rod get a Breech Rod Guide and that CLP stuff. Trust the wisdom of the people here.

I prefere the Carbines myself. I think you would be well served with either though.

The best part about an AR is that whichever you decide on, doesn't have to be permanent.  Have a 20, want a carbine; buy a new upper.

With optics, a carbine and a rifle are equally as accurate.  The different size in barrels matter with;
1) Proper sight radius
2) velocity/proper fragmentation.

With Iron sights, a 20" rifle will be more accurate at longer distances, BUT if you get a disapator or use optics then there is no issue of that.

Velocity of a 20" of course is faster than a carbine, so again at long distances, a rifle will be more accurate than a carbine.  However for target shooting, both are fine up to 300 meters (or is that yards?)

I prefere the Carbines also.

Here's my story. A little over a year ago I decided I'd buy myself my first personal AR. I wanted it to be the same dimensions as the M16A2s I was issued in the Cavalry. I hadn't even considered the carbine versions.

I went and bought myself A DPMS Panther Classic with the heavy barrel. It is super accurate. I once had a .246" 5-shot@100yd group while load testing, using a carry handle mount. That's sub-1/4" accuracy.

After the newness wore off I started shooting it less and less. The biggest problem I think I have is the weight. The weight is advertised a 9 lbs. If I remember right, the weight of my service rifle was 8.75 with a FULLY LOADED 30-round magazine. It just seemed like a big pain in the ass to haul around, since I'm on the road all year working construction.

Well, after not posting anything here for about 6 months, I finally started hanging around, trying to find ideas for a lighter settup. The rifle has sat behind the door of my den for too long.

I've decided to order the 'superlight' 16" barreled assembly from Bushmaster, and install the new Rock River Arms 'Entry Stock', which is 2.5" shorter than the standard A2 buttstock. This is about the only option I have besides selling it, and I really think it would make a good defesive arm.

With the above componants installed, it would be as short and light as I can legally make it(post-ban). I've been reading about some new 'TAP' rounds and would probably use this set-up to replace my 1911 as a 'camper gun', while on the road.

So my advice would be to get the shorter/lighter version(the 16"). My thoughts would have been different last year though.
If you're like me, you might not get as much use out of the target model. I wouldn't mind carrying a carbine around in the woods. I wouldn't even think of hiking with the one I have now. In fact, it has been left behind several times in the last year, where it's .223 caliber would have probably been the best choice. When I get it lightened it should make a great utility gun.

Good Luck
Kevin

Well go ahead and Get the Carbine , then just buy the 20" Vmatch or Match Target upper, so your talking one complete gun and one upper for an extra $565.00. Takes just a few minutes to change between one and the other.  The 20" will give you about 150+ FPS more Muzzle Velocity, plus your bullet will stabilize quicker (hence your battlefield zero will be slightly different from the 16" to 20" but if you buy complete upper it won't make any difference.  Its good to get good and comfortable with Iron sights.  Uhh what else,  Read the Marines Eval the M4 thread before you buy anything.   This gave me a lot of information.  Learn how to dissassemble your rifle, etc... 1/9 twists are good for up to 75Gr, They say, but some peoples will not through that high, say 68 to 69 gr bullets safely.   Good Glass and ammo are as important as your rifle.  Since you are going with Match Target , I don't think it is a sammi spec barrel, which means it will eat almost everything,  M855,Q3131A, 55gr FMJ , but also the WOLF ammo too.  NEVER BUY S&B AMMO Anything. what else.