I have measured the MV of three of my guns thru two different chronos and always get 125-175 less MV than Mfg. specs.All my guns have 22" barrels.They are a 243,270 and 3006.Is this the norm?

most MV's are from a 24 inch barrel by most manufacturers,and in a controlled setting,usually inside at a set temperature and more controlled humidity,all these have different effects on muzzle velocity a 200fps decrease doesn't mean much as long as the ammo is accurate out of your guns.

The fps rating is 100% valid ONLY IF you are using a test barrel which is usually a bit tighter and longer than conventional factory rifles.

Take a look in your reloading manuals. Most manuals tell you on the front page of the cartridge you are loading for what firearm the results were taken in.
Many were taken in barrel lengths longer than the standard hunting rifle. Some debate the point, but you can GENERALLY take about 25-30 fps. MV off for each inch of barrel your gun is shy of the test firearm. Again, some of us question the published MV figures from the factory for their creations to begin with............

Don't worry, the deer won't notice.