5.7×28 has been around for years, thanks to FN. Even so, some people are just now discovering it thanks to some newer products from CMMG, like the CMMG Banshee. The gent over on the VSO Gun Channel thinks you should take a good look at the 5.7×28 and even stacked it up against the ever-popular 5.56×45 in a short barrel configuration. He addressed the round and explains why you should give it a go if you haven’t already.
Admittedly, the 5.7×28 is an uncommon round.
It was designed for the FN P90 rifle with fast-burning powder, but lots of people do not enjoy the stick magazine that goes with the P90. With the release of the CMMG 5.7 magazine, it allows your AR rifle to shoot 5.7 — with a 5.7 upper, that is. But how would the 5.7 compare to the 5.56?
VSO really wanted to compare the .22lr, 5.7×28, and the 5.56×45 as the 5.7 falls in the middle. Ultimately, he excluded the .22lr round because it’s a non-combat rimfire round, even though commenters of the videos say that .22Mag or 9mm would be a better comparison. VSO goes on to say that .22lr is outdated and has been riddled with reliability issues throughout the years. The 5.7×28 round is a centerfire cartridge that has a higher quality projectile as well.
The magazines from CMMG have the same general appearance as an AR mag, but hold 40 rounds of 5.7×28 ammo. They have a small texture on the front of the mag and hold the bolt open on the last round but don’t fall free. Then why would you want to run them in an AR? It essentially comes down to the fact that with the CMMG upper, it is more compact and lighter than its 5.56×45 counterpart—including the suppressor. When you throw in having a lower papered as an SBR (short-barreled rifle for those that don’t know), having the upper adds to the overall latitude of configuration options for the firearm, including full auto if applicable.
The 5.7 round has a reputation of being one that screams. The cartridges are designed to shoot out of the short barrel and CMMG has options for either a 5” or 8” barrel length. VSO decided to use barrel lengths that were similar for the 5.56 and the 5.7. Whether or not it’s obvious, the suppressors are different. The 5.7 round can be shot through a smaller rimfire suppressor (in most cases) whereas the 5.56 would need a rifle suppressor.
Testing the Rounds
VSO compared the two rounds during the day and the night. The night testing showed the light signature of both the 5.56 and the 5.7 was significantly lower when shot suppressed vs not suppressed. However, the 5.7 had far less signature in both applications. Then he did something that was either brave or idiotic when he shot two rounds of 5.56 through his Bowers USS .22lr suppressor. Thankfully nothing crazy happened.
Major Positive take-homes
- The 5.7 configuration is shorter overall length than the 5.56
- 5.7×28 ammunition is more compact and lighter
- Suppressors designed for 5.7×28 are generally lighter and smaller
- Less recoil thanks to the lighter reciprocating mass in the operating system
- Package is good to deal with secondary or tertiary targets
Downsides of 5.7
- Ammunition is not super common and may take some calling around to find it in local stores.
- Not all ammo loads are created equal and he recommends either Vanguard Outfitter or FN57 branded ammunition.
In short, the 5.7×28 is a great compact option and even a majority of the commentators of the video agreed. Even so, he’ll probably stay with the 5.56×45 as his primary option.
Great, well thought out article. Thank you.
both my 5.7 the pistol and ps90 are well made and shoot wonderful
nary a problem with either one, several thousand rounds downrange.
con… ammo is pricey today.
always be safe on the range.
have you fired the P50?
The Chief of Police where I worked wanted to change our weapons to the FN 57 and the P90. He thought the P90 was cool. No research or vetting, just did it. While making the arrangements FN gave me a contact number for any questions or issues. As the switch was taking place, FN was always easy to contact and have questions answered. When the switch was completed and a few weeks passed we began to have problems with the pistol. The loaded chamber indicator on one pistol popped completely out while being fired. Failure to ejects, etc.. The final straw was when the weapons failed to fire. We couldn’t figure it out and guess what, no one was answering the phone at FN. After two or three months we finally made contact with our FN guy and related the problem. After asking the batch number of our ammo he said it was a bad batch and to send what we had back while they sent new ammo. Bear in mind, we had to contact them and it was apparent they knew the ammo was bad but made no attempt to contact us. I was livid that they put our lives on the line like that. Within the year, we got rid of all FN weapons and went back to Glock. Beware of these weapons if you using them for defense.
Don't see enough advantages to switch.