bluez a lot of cast bullet shooter are under the impression that just using a hard alloy will eliminate leading or that shooting cast bullets at high velocity will also cause leading. Leading is caused by a combination of things,improper bullet fit,using the wrong lube for the task at hand and a combination of pressure and velocity that is to high for the particular bullet alloy used.
Lead bullets can handle pressure and velocity up to a certain point but beyond that point is where the gas check comes into play,not only does it allow you to shoot a somewhat softer alloy than you normally could with the same load but it allows you to shoot both high pressure and high velocity loads by sealing the bore much better.
As to your question yes you can shoot the Lee 150 gr. bullet at 2200 fps. in fact there is load data that takes that bullet up to 2300+ fps. The question is what is the intended purpose for the load you want to work up and do you need that much velocity. Two of my favorite loads I shoot in my 30-30 pump gun are with the Lee 150 & 170 gr. gas check bullets. For plinking loads I cast both bullets from straight WW alloy with a BHN of around 12,give them two coats of Lee Alox tumble lube and leave the gas check off,MV runs around 1200+ fps and they work just fine for target shooting and small game and are as accurate you can hold them.
For Southern white tail deer I cast the same 170 gr. bullet form 30:1 Lead/Tin alloy with a BHN of around 9 bullets are gas check and pan lubed and shoot at about 2000+ fps. I apply my gas checks with the Lee .311 push through sizer,neither load combination has ever leaded the bore on my Sav 30-30.
Here is a good online reference that will give you lots of good info one cast bullets.
http://www.lasc.us/Fryxell_Book_Contents.htm another excellent reference would be
http://www.lbtmoulds.com/books.shtml
