would like data for sub-sonic loads or web -site where I could find it....

I doubt .223 can be loaded subsonic, but I could be wrong. I know a .22LR can be, but the difference in powder charges is what... 10X? If you could load to less than 1089 ft/sec at STP, the range would be very short, yes? Maybe the gun, if it's an AR type, wouldn't cycle reliably for lack of adeqaute gas pressure and volume. Just my thoughts...

Rootbeer,
Yes, you can load the .223 down to subsonic velocity. I do it all the time for plinking/tree rat loads in my 10" Contender. They are still quite loud. And, no, they will not function a semi' such as an AR. They will fire just fine, but you have to manually cycle the bolt - not always a bad thing.>>>>>>>Bug.

I have loaded .223 with Unique and only get 1500-2000fps with these loads. If you used a fast pistol powder you could get subsonic loads. Ideally if you had a rifle with a 8" or 9" twist then you could use a very heavy bullet such as a 70-80gr VLD where you could seat the bullet deeper to help take up space in the case.

Sorry I don't have any load data to get you subsonic.

Brandon

I quiet is what you want, an adapter that shoots 22LR in your .223 chamber can be had for $20.

I really can recomend Alex Adapter as a supplier:
http://alexcartridge.com/