More Than Meets the Eye? Fiocchi Range Dynamics 62gr FMJ 5.7x28mm
The FN 5.7x28mm round has increased in popularity over the last 3-4 yrs. As of writing, we now have guns chambered in 5.7x28mm being produced by Ruger, Smith and Wesson, Palmetto State Armory, and CMMG, to name a few. The 5.7x28mm cartridge’s claim to fame is its ability to drive 28 to 40 gr., .22 caliber bullets at speeds of 2,300 fps (FN SS198LF) to around 1,700 fps (Fiocchi Hyperformance ballistic tip) from the pistol!
But what if we take away the 5.7’s speed and are presented with a round that’s target velocity is under the speed of sound (1,130 fps, “Sub-Sonic”)? With the influx of firearms shooting 5.7, new loadings have been introduced, including the Fiocchi Range Dynamics subsonic 62gr FMJ.
This round, when paired with a suppressor, makes for a very quiet shooting experience. A majority of the 5.7 variants I’ve tested function well with this round, and typically it remains subsonic for barrel lengths up to 10”. It has a street price of around $1/rd. Given that this round operates at the same speed as a majority of .22lr, how does it compare ballistically? For our article, the .22LR competitor will be CCI’s “Sub-Sonic” 40gr lead hollow point and their “Quiet-22” 40 gr lead round nose, which will be fired from a 16” S&W M&P 15-22 with a JK Armament rimfire suppressor. We will use an FN PS90 SBR with a 10.4” barrel, as well as, a CMMG MK57 with an 8” barrel affixed with a Yankee Hill Machine Turbo 5.56 suppressor.
Velocity Testing
We fired ten shots of each ammo type across a Competition Electronics ProChrono DLX Chronograph. Weather considerations for the day of recording were as follows: air temp of 46°F, humidity of 44%, dew point of 25°F, barometric pressure of 29.09” HG, and elevation of 849 ft. For these to be subsonic, they should stay under 1,130 fps. With the Fiocchi 62gr FMJ, 3 of the ten shots were supersonic. All the 22LR rounds remained under our threshold:
The Quiet-22 round did not cycle the action of the M&P 15-22, but the standard “Sub-Sonic” round did. No cycling or firing issues were present in the Fiocchi 5.7 round.
Accuracy Testing
To test our accuracy/precision, we mounted our guns on a solid bench using a Caldwell Hydrosled 2 and affixed a 3-18x Primary Arms FFP scope to the S&W M&P 15-22. The CMMG MK57 used a 1-6X SFP scope and later the same 3-18x from the 15-22. The P90’s bullpup design does not lend itself well to being fired from a sled, so that is the only reason the MK57 was used.
At 25 yards, the “Sub-Sonic” CCI load just slightly out averaged the Fiocchi 5.7 FMJ load group size. We took the target out to 100 yards, and with my skillset, our “Sub-Sonic” CCI load was the clear winner. The “Quiet-22” had the worst accuracy at this distance, and I did not measure the group size.
Gel Performance
To get an understanding of how these 3 rounds could perform against soft tissue, we selected to use Clear Ballistics synthetic ballistic gel. Clear Ballistic gel is re-usable and the block for testing was re-melted 2 times before being used for this test. It is of the standard 10% density and measured approximately 6”x6”x16”.
The block was placed 13 feet from the muzzle. Our “Quiet-22” had the shallowest penetration followed by the “Sub-Sonic”, and the clear winner was the Fiocchi 5.7 62gr FMJ at 14.25” of penetration. We saw no terminal effect from the “Quiet-22” other than what is typically described as ice-picking (straight line penetration with little tissue disruption). Our “Sub-Sonic” hollow point expanded, and the Fiocchi 5.7 tumbled /yawed twice during its travel.
Conclusion
As of writing this article, I’ve fired 400 rounds of our Fiocchi 62gr FMJ subsonic ammunition through our various 5.7x28mm guns. It has proven reliable and very pleasurable to shoot suppressed, even with it being supersonic in our longer barrel lengths. While I agree that the FN 5.7x28mm was designed to propel lighter 22 caliber bullets at high speeds, I like the versatility of reliably firing a wide variety of bullet types through one platform. Our fundamental gel tests, in my opinion, prove that it provides superior wounding in soft tissue over subsonic .22lr ammunition types, all while providing better reliability than rimfire and comparable accuracy to boot. Thank you to Fiocchi USA for sending us the 62gr Range Dynamics 5.7x28mm to review!
Firearms are the main focus for Matt’s channel, Buffman R.A.N.G.E. From handguns to shotguns, ammunition, gear and more. His Motto, which he added to the channel name stands for Reviewing Ammo-N-Guns Everyday (R.A.N.G.E) Matt celebrates our 2nd Amendment Rights any way possible while maintaining a safe and educational environment.