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5.56x45mm Fired From a 7.5″ Barrel is Just a Glorified .22LR
This is a followup to my recent post regarding why super short barreled AR-15s chambered in 5.56x45mm are more viable than they used to be thanks to various advancements in projectile design, flash suppressor technology, and more. The article was never intended to say they were the best choice. In fact, I clearly state that other calibers are more efficient in such short barrels but, as usual… the internet overreacted.
One of the more common comments was a variation on the theme of the 5.56 being roughly on par with or only slightly better than a .22LR at the modest velocities produced by 7.5″ barrels. That is the kind of gun counter dogma that makes some sense on its surface because you are giving up some velocity by using such a short barrel and that is not good news for terminal performance. However, this statement just doesn’t hold up with even a cursory examination of the data.
Let’s compare a high velocity .22LR with some 5.56/223 rounds that have shown to be solid performers in shorter barrels. We can compare mass in grains, velocity in feet per second, and energy in foot pounds.
CCI Stinger .22LR
- Mass: 32 gr
- Velocity: 1640 fps
- Energy: 191 ft.lbf
Hornady TAP 5.56 55gr GMX
- Mass: 55 gr
- Velocity: 2340 fps
- Energy: 669 ft.lbf
Winchester Ranger 64 gr 5.56 (RA556B)
- Mass: 64 gr
- Velocity: 2210 fps
- Energy: 694 ft.lbf
Speer Gold Dot 64 gr 5.56
- Mass: 64 gr
- Velocity: 1930 fps
- Energy: 529 ft.lbf
Remington Hog Hammer 62gr TSX
- Mass: 62 gr
- Velocity: 2090 fps
- Energy: 601 ft.lbf
Much of the velocity data came from the poboyspecial Youtube channel.
The data represents just a few of the rounds that perform well from such short barrels. It doesn’t even include a 50 gr TSX load which is considered the gold standard of performance from such short barrels. As you can see, all of the loads sampled here are significantly faster and heavier than 22LR which adds up to significantly more energy. What you can’t see is that all of them exhibit expansion and penetrate well beyond the FBI minimum.
The data shows that, in terms of energy, a well selected .223 or 5.56 round out of a 7.5″ barrel outperforms many .45 ACP and .357 Magnum loads at typical handgun velocities. That really isn’t all that impressive considering that those are handgun loads but it does shows adequate performance for the very limited role you might use such a barrel/ammo combination. When used in a PDW type role, you get a weapon that has extended capacity and usable range beyond a typical handgun, along with fringe benefits likes increased accuracy and ease of accessory mounting (white lights, optics, etc.).
I think it is clear that you the 5.56/.223 is hardly ideal out of such short barrels but to say it is comparable to a .22LR is ridiculous. Choosing a compact package for a specific role is a compromise. You make a similar compromise every time you carry a handgun instead of a rifle. Context is the key.
Ballistic Advantage Releases AR-15 Lower Receivers
Ballistic Advantage’s new AR-15 lower receivers are now available. These forged 7075-T6 aluminum lowers are hard anodized and feature a nylon tipped tension screw for tightening upper and lower fit, a threaded take-down pin detent hole, and a flared magazine well.
AZCDL Benefit Lowers from KE Arms
The Arizona Citizens Defense League is an organization dedicated to protecting and promoting the citizens of Arizona’s right to keep and bear arms. KE Arms, an Arizona based firearm manufacturer, has a vested interesting in these very principles. 5% of the proceeds from their new AZCDL Engraved AR-15 Lowers will go directly to the AZCDL.
These lowers will be distributed by local FFL holders in AZ. Contact KE Arms to find out if an FFL in your area will be carrying the lowers.
Times Have Changed: Why You Might Actually Want to Try a 7.5″ 5.56 AR-15 Build
I have been shooting AR-15s for years now and apart from the mild cool factor, I have never really considered owning an AR-15 chambered in 5.56x45mm with a 7.5″ barrel. In fact, you could say that I thought they were a bit silly. Times changes and so do opinions.
It is true that just about any other common AR-15 chambering is a better performer than 5.56/.223 in such short barrels. That includes 6.8SPC, 300BLK, and even the 9mm Luger (in some ways like noise and flash but not necessarily in terminal ballistics). If you want to build a super-short AR-15 and your budget allows, go ahead and take on a new caliber. If your budget doesn’t allow or you just don’t want to take on a new caliber, there are a five reasons that super short 5.56 chambered guns may finally be viable.
Here is how I talked myself into building one…
- Ammo – The proliferation of advanced projectiles like the Barnes TSX and some bonded bullets means that there is finally off-the-shelf ammunition that will expand at the more modest velocities produced by 7.5″ AR-15 barrels. There are new choices coming out all the time and projectile design continues to advance at an amazing rate.
- Muzzle devices – Previously, having a super short 5.56 chambered AR-15 meant throwing massive fireballs every time you pulled the trigger. That is no longer the case. Advanced flash suppressors like the AAC Blackout, White Sound Defense FOSSA 556, B.E. Meyers 249F, and others can all but eliminate the flash on these shorter barrels. This is especially true if the shooter chooses their ammo carefully. If you don’t care about flash, there are a now number of linear comps on the market that will direct some of the blast away from the shooter and some even suppress flash a bit like the Black River Tactical Covert Comp. You can even couple a blast shield with an effective flash suppressor like the Griffon Armament taper mount series or a YHM Phantom with a Simplistic Shooting Solutions Blast Shield to suppress flash AND direct concussion away from the shooter.
- Reliable barrels – There was a time when there weren’t very many 7.5″ barrel options that worked well without being grotesquely over-gassed. Noveske was pretty much the only quality option. Now, you can get high quality 7.5″ barrels from Ballistic Advantage and Aero Precision just to name two. Both use gas port specs that are on the small side and their barrels run well. You can also go with a piston set up from PWS or Adams Arms, both of which have solid reputations for reliable function. If you don’t want to build your own, Andro Corp Industries offers prebuilt 7.5″ uppers that use Ballistic Advantage barrels. I purchased mine from them and I have been very pleased so far.
- Law Tactical AR-15 Folding Stock Adapter – The moment that I finally laid hands on a Law Tactical AR-15 Folding Stock Adapter was the moment that I hoped I could make a 7.5″ AR-15 work. An AR-15 pistol equipped with a 7.5″ barrel and folding stock adapter will measure at right around 18″ long when folded. That means it can be carried in a normal backpack, tool box, messenger bag and all sorts of other places that even a 10.5″ barrel won’t fit without breaking it into its separate components. The Law Tactical Folding Stock Adapter helps turn these builds from interesting range toys to something like a concealable PDW with potentially interesting application for the private citizen.
- Advent of the AR Pistol – Finally, the advent of the AR-15 pistol has made it easier, less costly, and less risky than ever to try a 5.56 chambered AR-15 with a short barrel. You can test and tweak various ammo/muzzle device combinations before you plunk down your cash for a tax stamp… or just keep it as a pistol.
To recap, 5.56×45 is still less than ideal from a short barrel but thanks to several advancements, it may be more viable than ever.