Is it worth getting a short-barreled rifle in order to save weight?

I have been getting questions from former students about 10.5” and 14.5 “ AR-design rifles.  The new interest has, I presume, been prompted by the repeal of the $200 tax on SBR’ s.  But the articulated reasons are reduced length and reduced weight. 

The short answer to this:  neither a few ounces of weight or a few inches of length are going to make any noticeable difference in how we use these rifles.  End of story.

Let me dispense with the “length” issue first.  Assuming there are no differences in the flash hiders used or suppressors added, the difference between a 14.5” barrel and a 16.25” barrel is 1.75”.  I am quite sure that 1.75” will make NO difference in how the gun handles or points.  Further, that 1.75” will usually be eaten up by length of the stock, especially if it is a collapsable stock, which they all seem to be today.

The 10.5” barrel will shorten the gun by 5.75”.  That is at least noticeable.  But somebody tell me how that will improve anything in terms of gun handling or marksmanship.  It might help conceal the rifle under a garment, but I don’t carry my rifles concealed, and I will be neither will 98 out of 100 of you out there.  This is fantasy stuff.  And it is hard to explain to a jury.

So, let’s talk about weight.  This is hard to calculate precisely, because there are so many things that make an AR-style rifle heavier or lighter.  Barrel weight is primary in this regard.  But the materials out of which the frame and hand guards are made, magazine capacity and construction, and optic choices are also significant.  So, I am forced to work with averages here.  (You nit-picking trolls will just have to stand down for a minute.)

There is about .3 lbs. difference between an M-4 style rifle with a 14.5” barrel and an AR with a 15” barrel.  That is 4.8 oz.  That is the weight of 11 or 12 rounds of .556 ammo.  One can save more weight than that by ditching the “magnifier” one will never use in a fight (.8 lbs) for a red dot (.3 lbs).  Going from a 30-round magazine with 28 rounds in it to a 20-round magazine with 18 rounds in it saves .3 lbs. (unless the magazines are steel instead of polymer or aluminum, in which case the weight savings are greater).

One would think the 10.5” barrel would increase the weight savings.  It might, but probably not.  It turns out, those little suckers tend to be heavy, mostly because they tend to have heavy barrels.  They can go over 9 lbs.  But they are usually around 6 lbs.  That is within .6 lbs. of the average 16.25” guns, assuming you resist the temptation to get the fancy barrel and optics and long magazines and so forth. 

One CAN get a very light, short rifle.  But the whole object of the exercise is to have a very cool toy with all the do-dads, so nobody does.

I will say that if all things are kept equal, moving weight from the end of the barrel to the center of the rifle makes it handier.  But putting aside the “cool factor,” I fail to see it is worth the expense, the loss in ballistic efficiency and the legal hassles.

What legal hassles, you ask?  Although the $200 tax is scheduled to be eliminated in January 2026 (at least for the moment), one still needs to register the SBR with ATF, and keep the paperwork with the gun at all times.  (People tend to forget that last part.)  And if one wants to take the rifle from one state to another, one must first get the ATF’s permission.  A condition of that permission is that the SBR is legal in the state to which one wants to transport the gun, which is not always the case.

All that can currently be avoided by getting a “brace” and calling the SBR a “pistol.”  But then you have the uncertainty of which “braces” are legal and which are not, and what that situation is going to be in the future.

Ballistic efficiency is sacrificed with shorter barrels.  By “ballistic efficiency” I mean whether the bullet, on impact, will function as it was designed to function.  The .556 rounds upon which we count to get the job done have to be traveling around 2,500 fps to function as designed. The velocity of the round at the muzzle drops as the barrel gets shorter, which means it is moving more slowly at any given range.  The tables I have consulted show a drop of 45 fps. going from a 16.25” barrel to a 14.5” barrel, and 109 fps. going from a 16.25” barrel to a 10.5” barrel (for 55gr. ball ammo; the drop is greater for .62 gr. bullets.)  The shorter barrels effect trajectory as well, necessitating recalibration.

But then again, nobody counts upon military ball ammo for defensive use.  There are dozens of different loads and bullet designs people use for “carry ammo.”  Some work fine from short barrels; but only out to more limited ranges.

I just read a publication that said the “effective range” (the term being undefined in the posting) for a round fired from a 10.5” barrel is 600 meters.  Somebody is selling something, and that range estimate is complete nonsense.  It’s so far removed from reality, I dare call it a lie.  The range at which a 55-gr. ball round will function as designed out of a 16.25” barrel is about 250 Meters.  It might travel 600 meters, but when it hits it will be just a wobbly a .22. caliber slug.  Shorten that range by about 50 meters for every inch of barrel one sacrifices.  Under 11 inches, they just don’t work at all, as a practical matter.

I guess I should also point out that based upon 30 years of instructing folks, and my own shooting experience, there are not 1 in 20 of you out there who can hit anything under 3 feet across at 250 meters with an AR, under ideal conditions, at least without adding the weight of a scope and a bi-pod.  500 meters is a total pipe dream.  Fortunately, at 50 meters ballistic degradation is not much of an issue.

So, what do I tell people?  First, I tell them what I have written above.  Second, I tell them what they really want is a new toy (preferably a new toy that will accurately aim and fire itself).  It’s your money.  So, stop making excuses, go and get your new toy, and enjoy yourself.  Just don’t expect the gun to make you a better shooter.

Finally, I would mention that if you want a cool new toy, why insist upon .556 caliber?  There are pistol caliber carbines (or “pistols,” with a brace) in 9 mm. and .300 blackout and other calibers that are different animals, but fun to shoot and quite effective at defensive ranges.  Those are much better suited to short barrels than trying to make .556 cartridges work in little bitty guns.