November 08, 2019
This article is intended for handloaders who have experience reloading for their bolt-action rifles and now want to handload for an AR-style semiautomatic rifle. A lot of you are out there, and I, myself, fell into this category not so long ago. I’ve walked the walk, and now I want to share what I’ve learned.
We need to get one thing straight. Developing safe and reliable handloads in a bolt-action rifle is less complicated than it is for a gas-operated autoloader. Why? Because burning propellant has only one purpose in a bolt gun—to propel the bullet out of the barrel. The shooter provides the power to cycle the bolt, extract the empty case, and feed another round. And, fortunately, nobody can work the bolt fast enough to extract the case while there’s residual pressure in the barrel.
In fact, if all of the propellant gas exits the muzzle (i.e., the primer or cartridge case didn’t leak or blow out), you’re a long way toward declaring your handload safe and reliable. It may still be “too hot” or may not meet your accuracy objective, but it’s not likely dangerous to your gun or you.
That’s not the case when firing an AR. Some of the gas is diverted—before the bullet exits the barrel—to actuate a piston, carrier, or operating rod. That’s the energy source required to retract the bolt, extract the fired case, and self-load another round from the magazine.
Like a bolt gun, an AR has hard physical features, but the design and operation are more complex. In either a bolt action or an AR, the chamber and bore may be cut tight or loose. However, in direct-impingement ARs, the gas port diameter and how far it’s located along the barrel are fixed. The gas port in a piston-operated AR is also fixed but may incorporate a size adjustment feature. In either AR action type, the buffer spring can be replaced to vary the spring rate over a limited range.
Depending on the pressure curve generated when firing a round, an AR may or may not function satisfactorily. That’s the major consideration when selecting compatible components. They have to operate the gun safely and reliably before you can begin to evaluate their ballistic performance downrange.
Hodgdon offers more than a dozen different propellants for reloading 223/5.56 ammo. Burn rates range from IMR 4198 (fastest) to CFE 223 (slowest). My experience shows, generally speaking, the faster-burn-rate choices work better with bullets weighing up to 60 grains. Compressed charges of slower-burn-rate propellants are more compatible with loading heavier bullets. Of course, Hodgdon provides load data for every bullet weight they’ve tested with all compatible propellants yielding safe and reliable ballistic data.
Several, including H335, BL-C(2), Varget, Benchmark, IMR 8208 XBR, H4895, and CFE 223 have proven to be the most versatile choices with all bullet weights.
I chose two of my favorite 223 Rem. rifles—a CZ 527 bolt action and a Sun Devil SD-15 autoloader—to use for this report, and I built a lot of handloads to shoot in both guns. For the load data chart, I narrowed them down to varmint-hunting bullets and match bullets weighing from 52 to 77 grains, and I loaded them over W748, H335, BL-C(2), Varget, Benchmark, IMR 8208 XBR, CFE 223, and IMR 4166 propellants. I also ran the numbers on my Powley computer and was surprised when it indicated IMR 3031 and IMR 4064 were the preferred choices for lighter weight bullets.
I also built some specialty 223 Rem. handloads with lightweight 40-grain varmint bullets and HP38, Trail Boss, and CFE Pistol. More about them later.
I had about 250 pieces of Lake City (LC) 5.56 NATO brass already prepped and ready to load. Many reviews state that military cases are heavier than commercial brass. I’ve weighed several hundred pieces having various headstamps and concluded, in most cases, the difference in ballistic performance is negligible. That’s not to say it’s just as easy to stuff a 77-grain bullet into the heaviest case you’re reloading atop a full charge of BL-C(2) as it is with the lightest piece of brass in the batch. Just that, in most applications, you won’t find a significant difference than if you simply segregate your cases by headstamp.
Reloading 223 Rem./5.56mm is mostly the usual routine. Clean and inspect the cases, lube and full-length resize/decap, clean, and inspect them again. Trim to length as needed, clean/uniform the primer pockets, reprime, charge with powder, verify powder charges, seat bullets to specific overall length, perform final inspection, box, and label.
That’s all there is to it except for a couple of additional steps that are required to prep military cases and brass. First, almost all military and some commercial rounds have crimped-in primers. The decapping pin in the sizing die may not be stout enough to knock these out without being damaged, so deprime them before resizing using a special die expressly made for this task.
Next, remove the residual rim of brass around the pocket. You won’t be able to reprime without damaging the primer or maybe even setting one off if you get frustrated and try to force it into an obstructed pocket. Special tools are made just for this purpose. Some swage, while others cut the pocket rim material out of the way. I’ve tried several of the swaging tools, but for me personally, the process is a hit-or-miss procedure. I generally prefer cutting the crimp away. If you choose this route, don’t get aggressive and recut the pockets too much. Only trial and error can teach you just how much force is required to cleanly chamfer the pocket lip and not cut away too much of the case material.
I’ve had good luck using the RCBS crimp remover tool mounted on the company’s powered case-prep center. The three-blade cutter is permanently and precisely mounted on a steel base to assure proper depth and angle of the resulting chamfer.
Another step I’ve found to be necessary when reloading for 223 Rem./5.56mm autoloaders is verifying the headspace. I use a case/cartridge headspace gauge to spot-check roughly 10 percent of my brass after completing case prep. If I find a “bad” one, I check the rest and put any that fail to fit the gauge aside.
You might be able to chamber that round in your bolt gun by forcing the bolt to close, but you’ll likely jam the action in an AR that the forward assist can’t overcome. It’s best to weed out any irregular cartridges to avoid problems later.
Competition shooters know that the bullet’s position in the chamber throat/leade can significantly affect accuracy. Occasionally, I have experimented with varying bulletseating depth to achieve better groups in my bolt actions, but the really short throat of the 223 Rem. cartridge case severely limits how much you can vary bulletseating depth, so I haven’t done much of it. However, my handloading mentor, John Redmon, who actually got me started in handloading the 223 Rem. many years ago long before I had any interest in AR-15s, has reams of 223 Rem. data showing how varying the bulletseating depth improved accuracy in his bolt actions. I’ve seen a lot of his targets that further confirm the fact that accuracy in bolt actions can be improved in this manner.
The bullet’s nose profile, i.e., the ogive shape, significantly affects the cartridge overall length (COL). The chamber throat/leade dimensions are also a major determining factor. If you’re not shooting a single-shot rifle, the length of the magazine box may dicatate the maximum COL possible.
Redmon adjusts COL so his test rounds will just fit the chamber and then incrementally reseats each five-round batch 0.010 deeper (up to 0.2 inch), searching for that special “sweet spot.” When shooting his handloads, he single loads each round in a rifle, so COL isn’t limited by the rifle’s magazine length. Some of his best results were with handloads measuring up to 2.320 inches.
When loading for a 5.56 NATO-chambered AR, the COL is restricted to 2.260 inches. Lighter bullets may be seated to a shorter COL, whereas the heavier (longer) bullets tend to fill up the extended NATO-spec chamber throat/leade.
While I’m sure my Sun Devil’s accuracy results could be improved by experimenting with bulletseating depth (the most accurate load averaged 0.38 inch at 100 yards and had a COL of 2.250 inches), determining the appropriate powder charge weight for each specific bullet to achieve reliable and safe functioning overshadowed my concern of where to precisely seat the bullet for optimum accuracy.
The load data chart shows that when shooting identical hand-loads in the bolt gun and the AR, the CZ 527 generally did better than the Sun Devil SD-15 with the lighter bullets, and the SD-15 typically grouped the heavier bullets better. Clearly, barrel twist rate and chamber throat dimensions do affect accuracy.