Has anyone here put enough semiauto rounds through a Colt chrome lined 1/7" barrel to actually cause considerable wear or wear one out?  I have a 16" 1/7" M4 barrel, not because I wanted it, it was on the rifle I got.  I plan on getting an extra upper with a 14 1/2" 1/9" Bushmaster with a permanent Vortex or Phantom for general use.  I would like to put a suppressor on the Colt 1/7", if I get the extra $700 with the stamp.  What is the expected life of a 1/7", not subjected to full auto use?

HP shooters regularly wear out barrels between 3500 and 6000 rounds.  "Worn out" to us means it won't group at 600 yards, though. 1:7 and 1:8 twists are the common twists in HP.   Expect that your accuracy will continue beyond those figures if you are shooting at shorter range.

I would also guess you are shooting a stainless barrel vs my chrome lined carbon steel, so I would expect a much longer service life.  

Agreed.  Chrome lined may get you as much as twice the barrel life.  Of course, barrel life becomes subjective.  When is the barrel "worn out?"  To an HP shooter, it may be "worn out" LONG before most shooters would even consider swapping barrels.  The average plinker may not see an accuracy drop off for 10K or more rounds, or if he's a lousy shot, he my go 50K before he thinks there might be a problem.  "Barrel life" must be taken in context.