Shot some UMC 147 grain through my CX4/Trident and was getting sonic crack. Is there any commercial ammo that'll stay subsonic in that long of a barrel or will I have to handload it?

Fiocchi makes 158 grain 9mm, which was originally loaded in this weight specifically to remain subsonic out of longer barreled UZIs.

I don't understand this, though, because I have a CX4 with AAC Evo-9, and I tried Winchester White Box 147 FMJ, and JHP, as well as American Eagle 147 FMJ. Both sounded the same to me, so I fired some 115 grain through my rig to get an audible difference, and sure enough, both the WWB and the American Eagle were staying SUB-sonic.

I don't know why your rig is going super-sonic, unless its just a colder environment? Maybe my rig is right on the border and the extra heat of Texas is all that mattered to keep it subsonic.

Try shooting some 115 grain to see if you can hear the difference.

Aside from that, you can always chase down the 158 grain.

I believe I had some Speer Lawman 147gr 9mm go transsonic in my 16" barrel. The stuff is at least twice as loud as any other manufacture or handloads, but I can't make out a sonic crack. Unsilenced, it's tied for the quietest 9mm ammo I ever shot. That's why I'm guessing it's transsonic.

I've never seen 147gr go supersonic in anything. I've tried every brand that I've found. The one box of that Speer stuff was the closest, but it might not have even been transsonic at all, just loud.

I've has several different makes go trans / super out of 10 ro 16 inch barrels - it can be a matter of dimensions, as a tight bore/chamber can increase the velocity of the same ammo.

Yeah, I bet my action opens really early with this stupid thing. I gotta get something to replace it.

you might try American Eagle 147 grain as it was the slowest factory 147grn I've chrono'd so far. WWB 147 was fastest.

Artful wrote:you might try American Eagle 147 grain as it was the slowest factory 147grn I've chrono'd so far. WWB 147 was fastest.

You're right, I was mistaken in my first post. The AE 147 I have is subsonic. The UMC 147 that I bought 1000 rounds of goes supersonic 4/5 times in the CX4. Ordered some bullets tonight and will work on a load for the carbine.

Seems like N320 is a good place to start?

It's recommended by many - doesn't give the highest velocity out my guns - how below 1050 fps do you want to be with your 16" barrel?

Right at 1050 is where I'd like to be. Once I get this UMC shot up I'd like to have one load for carbine and pistol. Getting maximum velocity in the 16" barrel would help the pistol have at least a little bit of snot to it.

Also, some of the "Canned Heat" might be something to look into. I've never tried it myself simply because the AE and the WWB work fine. Still, that is yet another avenue to look into.

On a seperate note - how do you have your CX4 dressed up? What optics and what sort of accuracy are you getting?

I can get 1.5 inch groups at 50 yards (not 100), and I've got a Burris "Short Mag" 3-9 on top if it. I had to put extra high muzzle loader rings to get the scope above the shoulders. Then I had to put 2 small washers under the butt-end side of the top rail to angle the scope-sight down towards the line-of-shot.

Funny thing is that at 65 yards, its still pretty much aligned with the crosshairs, so I guess the subsonic 9 must have a kind of steep trajectory.

do you have a chronograph? - I'd shoot for 1010 to 1025 out of the 16" then seen what you get out of the pistol.