Yep, but that ammo has been banned from further import...Its designers had to create a small caliber cartridge that could penetrate a kevlar helmet at 200 meters. They succeeded.
.. And perfect size/shape for an AR platform, maybe.?a semi auto rifle in 4.5 x 28,,,now you're talking a REAL gopher shootin rifle!
Sounds like someone has a reamer.....You wouldnt happen to be able to chamber a CZ barrel???? Did you make a new bolthead for the 12 or put a bushing in it???The 5.7x28 necked down to 17 makes a sweet Squirrel round. Reamed out a good 17HMR Contender carbine barrel and it makes the perfect drive-by gopher getter. Put a cheep Green Mountain barrel on a Savage model 12 and it makes a easy sub 1/2 MOA rifle. Need some more range time, but it looks real promising.
Sure would like to put a 17 barrel in the five seven pistol just for fun.