Shooting the Lightweight AR15 Pistol Project – Loads for AR Pistols & SBRs Part 2

After reviewing all the parts that went into this Shooting the Lightweight AR Pistol project the questions remains: How does it shoot and what are the Best 5.56 / .223 Loads for AR Pistols & SBRs?
Editors Note : Caution, ammunition reloading can be very dangerous, read our “Reloading Disclaimer“ .

U.S.A. –-(Ammoland.com)- In the first part of this article, I assembled a state-of-the art lightweight AR pistol that had many incredible features from a variety of innovative companies. The only thing that I omitted from that article was how the gun shot. Now, I could’ve gone and tried some factory loads and called it a day, but I’m a pretty comprehensive guy. I instead opted to go the route of discovery and conduct come ammunition loading experiments to determine the best 5.56/.223 loads for AR pistols and SBRs.

To write a disclaimer here first, I’m an expert handloader. Making your own ammunition and playing with a rifle’s gas system can spell disaster if you’re not careful, so please do not take what I’m writing here as gospel fact. You need to exercise caution and determine what you feel is safe. Some of the loads listed here may not be safe in your guns. I take nor assume any responsibility for anything that may happen to you. Now onto the fun.

For my control set I did indeed use factory ammunition. The load I used to establish baseline performance was the new Hornady 75gr HD SBR from their BLACK line. The Hornady load is advertised as being made for SBR-class weapons and I felt it could give me a great picture of performance. It is with this load that I tested initial velocity and gas pressure with the Superlative Adjustable Gas Block and 10.5” Faxon barrel.

All loads were fired over an Oehler 35P chronograph at a distance of five feet from the muzzle at eighty degrees Fahrenheit.

The first testing was conducted with a bare muzzle. Also, I completely shut the gas block off and fired five rounds. The velocity was 2290fps with a standard deviation (SD) of 6fps. With the gas system off, the gun did not cycle between shots.

I incrementally opened the gas system one ‘click’ at a time. The Superlative gas block has notches in the valve that you can open using a supplied wrench. I had to open the valve five clicks before the weapon would begin to cycle. The velocity at this point was 2285fps with an SD of 12fps.

The weapon would not cycle reliably until I opened the valve to click ten. At this point the bolt traveled a full stroke and locked back when the magazine was empty. The velocity at this click was 2277fps with an SD of 15pfs. I considered this to be the most reliable gas setting with this factory load.

I opened up the gas system a click at a time to click fifteen. At this point, the gun was significantly over gassed. The perceived recoil increased as did the ‘gas in the eye’ that everyone hates. I noticed a drop off in velocity at this point. I was getting 2257 fps with an SD of 20.

I came to the conclusion that the tuned gas system at click ten was the cleanest and most reliable setting. Any less and I wasn’t getting a reliable weapon. Any more than ten resulted in a dirty and gritty gun with more felt recoil. I returned the gun to click ten and spun on the SilencerCo ASR flash hider and later the ASR muzzle brake.

The ASR brake virtually eliminated all felt recoil, as was to be expected. The difference in velocity between the brake and flash hider was negligible. The only major difference was that there was a small change in point of impact and a higher SD (standard deviation) on the brake. I again averaged about 2277fps and had a respective SD of 17 and 12 for the brake and flashhider. Those numbers were so close that I couldn’t really call them different. For the remainder of the testing I used the ASR brake due to the reduced recoil.

When it came to making ammo, I contacted my dear friends at Graf and Sons. Not only is Graf’s the place to go for our obscure calibers and the supplies to load them, their customer service is top-notch. Graf’s supplied me with several materials to use for this test.

I decided that I would do this experiment in bulk using what most shooters would use in the circumstances. My brass would be nothing special and consist of once or twenty times fired range brass and military junk. I wanted to use this type of brass because it is what nearly everyone that owns an AR reloads with. I processed the brass and full-length sized it before trimming.

Friends, if you bulk load 5.56/.223, you absolutely need a “World’s Finest Trimmer” from Little Crow Gunworks. This is a trimmer that you put in your drill to make it spin and it indexes on the shoulder of the case. You must full-length resize to use this tool. It normally takes me an hour to trim fifty cases on a regular trimmer, but I can do that many in two minutes using this wonder. This is seriously one of the most necessary tools made for an AR reloader. You simply must have one if you don’t want to get married to that reloading bench and case trimmer.

With the cases trimmed, I primed the brass with standard CCI small rifle primers and then set about researching load data.

It was interesting to me that so few places had available load information for SBRs. I feel like there are an increasing number of people that own 5.56mm rifles with a barrel of about 10” and there should be the data to match.

My logic didn’t prevail and I quickly found that I was swinging blind and I conducted what research I could into the best powders and charge weights for this size of weapon. Graf’s sent me three powders to use: IMR 4198, Vihtavouri N133, and H4895 as well as 62gr Prvi Partizan FMJ bullets. I would end up making loads for both 62gr and 55gr bullets. I determined that these powders were in the burn rate range that could give me good results and set about making ammo.

I had really no idea how any of these were going to perform or cycle in my weapon. I knew that I would be getting a slightly higher SD due to the variances in case volumes, but that was about it.

My results surprised me a bit. My velocities were about what I expected, but I was disappointed in the lack of performance by the 55gr bullets. I played a pretty tight game with getting close to the published maximum loads in most manuals and even then I didn’t get reliable cycling out of my weapon.

The interesting part of this is that there was only about two grains difference between most loads and the performance was often wildly different.

Something I noticed was that the military and range brass I was using didn’t have as wide a variance as I’d imagined in terms of SD. The higher charges universally equaled a lower SD. I imagine that this has to do more with the gas pressure in the gun than in the cartridge wall variations.

The fastest loads were achieved with H4895. The 2522fps achieved using the 62gr bullets was impressive considering that that isn’t much slower than a standard length barrel using the same bullet weight. ( See Related AmmoLand article : AR-15 Rifle Barrel Length – Does It Even Matter? Maybe NOT )

Another interesting note is that I had a very hard time getting the IMR 4198 loads to cycle reliably on any gas setting. I had almost no ability to cycle and eject using the 55gr loads with this powder and had slow cycling and no bolt lockback on the 62gr loads. I played with this load using the adjustable valve and wasn’t really able to get it to function in the way I expected it to.

Best Loads for AR Pistols & SBRs

I determined that after all of this was done, I needed to take a closer look at the H4895 loads in both 55gr and 62gr varieties. I ended up firing close to a thousand rounds out of the weapon in the course of testing and evaluation and understood that my best accuracy at distance came from heavier bullets. I managed to fire the gun at 200 yards and discovered that using the SIG 77gr ammo from part 1, the Hornady HD SBR load, and my 62gr/25gr of H4895 loads, that I was able to group about 5” at this distance using the Scalarworks iron sights.

My handloads were easily above the accuracy standards of 3-Gun competitors, hunters, and backpackers. The 55gr loads were the least accurate and shot about 10” at 200, 4” at 100, and about an inch at 25yards. This is still just fine for what most people will use an AR for and in normal use and plinking you’d never notice. Using the more accurate 62gr load, I was able to go twenty for twenty on a 10” steel plate at 200 yards from prone.

The Faxon barrel impressed my beyond belief.

At closer ranges I fired for accuracy and was happy to find that the gun shot about 2-3” at 100 yards with the three loads in the last paragraph and it tightened up from there as you closed the distance to 25 yards. There really wasn’t a challenge at closer distances since I started at 200 and worked my way in. The gun just dropped them in right where I pointed it. I was happy with these results and called it a day.

What is my takeaway from all this on loads for AR Pistols & SBRs?

With the increasing popularity of SBRs and AR pistols, the discerning owner should make use of the upper end of slower-burning powders. Based on my results and my control load, I would recommend the use of a heavier bullet. A heavier bullet in the 62-77gr range will give you a better load and ballistics for the same speed as a lighter bullet.

So there you have it. I didn’t blow the gun up, but it’s always good to play it safe. I would like to thank the wonderful companies that made this article possible.

• Graf and Sons ( www.grafs.com )
• Little Crow Gunworks ( www.littlecrowgunworks.com )
• Hornady ( www.hornady.com )
• SIG SAUER ( www.sigsauer.com/products/ammunition/ )

For the complete list of companies that contributed parts to build the AR featured in this article, please refer to the Part 1 of this series.

About Josh Wayner:

Josh Wayner has been writing in the gun industry for five years. He is an active competition shooter with 14 medals from Camp Perry. In addition to firearms-related work, Josh enjoys working with animals and researching conservation projects in his home state of Michigan.

Editors Note : Caution, ammunition reloading can be very dangerous, read our “Reloading Disclaimer“ .

This post Shooting the Lightweight AR15 Pistol Project – Loads for AR Pistols & SBRs Part 2 appeared first on AmmoLand.com Shooting Sports News .