Originally Posted By: Plant.OneOriginally Posted By: DiRTY DOGDepends on the bullet. For example, Barnes recommends impact velocity about 1800 fps for the TTSX to expand reliably.
as a blackout shooter - and hunter - chasing sub 2000 fps expansion velocity hunting bullets and sorting them out from the standard .308 stuff has almost become a hobby.
the Tac-Tx 110 & 120gr "blacktip" will expand down to 1400 FPS.
hornady's vmax, SST, FTX, GMX all have terminal thresholds down into the 1600 fps range
lehigh 108gr CF bullet has a terminal threshold down to 800 fps.
sierra has two 30 caliber offerings that go into the 1500 fps range - the new 135gr HP "varminter" and their 110gr HP.
speer 125 tnt's terminal threshold is 1500 fps.
there are also multiple offerings for heavy / subsonic options that expand down to pistol level velocities - 750-800 fps type stuff.
the 90gr hornady .309 XTP expands down to around 800 fps, and from what i understand quite violently expands in the >1800 fps range. unfortunately that one isn't AR friendly... the bolt/single shot folks only get to mess with that one. but they have the option of running this as a 110gr sub thats dog fart quiet with a supressor.
the sierra 135 varminter shows some great accuracy potential in early testing i've done. with a 2000 FPS muzzle velocity and its 1600 FPS terminal threshold, its a reasonable 200 yd hunting bullet. i havent run the numbers yet, but its safe to assume that you could come up with a nice wide MPBR zero that could easily push into 135 yd range - which would more than suit my whitetail needs. I plan to do more accuracy testing as this may well end up being my new whitetail bullet! i tested some loaded ammo within the last few months from Ozark and at 2155 FPS and shot sub 3/4 MOA for me.
I'll have some bullets ordered here soon to test when spring gets its head out of its collective butt and decides to make more than a 72 hour appearance
my point is - there's lots of stuff out there that will expand under 2000 fps - you just have to search for it.
I don't know what you mean by the term "Terminal Threshold". Are you referring to minimum expansion velocity? If you are referring to minimum expansion velocity your numbers sound way off. Quite simply you can't get around physics. 2000 FPS is somewhat of a hard number in regards to the deformation properties of copper jacketed lead bullets. There are some ways to get around this. In the case of the Barnes #30811 110 grain Blacktip bullet for the 300 Blackout it offers some expansion down to 1350 FPS because it is basically a hollow point pistol bullet with an extremely large polymer tip.
The Nosler 64 grain BSB in .224 is able to offer expansion down to 1600 FPS due to a large exposed flat lead nose at the expense of ballistic coefficient. I would not count on the Hornady SST offering anything close to reasonable expansion down to 1600 FPS. Even Hornady recommends a minimum of 2000 FPS for every bullet you mentioned. I would not take any information from a tech rep over the phone as gospel because I have received incorrect information from them before.
The Nosler 125 grain BT advertises an expansion velocity down to 1800 feet per second but during my own testing with wetpack it offered no expansion at over 1900 FPS. Like I said before if you want consistent and reasonable expansion 2000 FPS is the magic number in regards to spire tipped rifle bullets. It is simply physics based on the mechanical properties of lead and copper. The only way to change that is to impart a mechanical design into the bullet such as a large hollow pount, exposed flat lead tip or an extremely thin jacket which typically results in fragmentation rather then proper expansion.