Needs some help. I have a 350 Legend build. Charging handle is sticky and will not close the bolt the last 1/8 of a inch.  Does this about 80 % of the time when pulling the charging handle back and letting it fly shut using ammo and when I use the side button to close the bolt. Will shoot 1 or 2 shots or 3 shots from  magazine and loading 1 bullet from magazine.  Does this on the pointed 150 gr Winchester ammo and flat nose FMJ ammo. FMJ  ammo I noticed runs slightly slightly better. Things I have tried On my  own are.....
1.......I have shot this complete upper on 3 different lowers Same problem.
2........I have tried  3 different Brands of magazines. Same problem.
3.........I Even cut lip down 1/8 of inch on a magazine to help bullets feed better over lip of magazine same issue.
4..........I have tried 3 different brands of ammo and gr of bullets in each of those brands. Same issue.
5.........I I have touched up the feed ramps a little. Same issue.    
6 ......... I have been running the gun wet with lube  all  the correct areas for now 200 Factory rounds ( bought ammo couple years ago When it was cheaper.  ) Same issue.  
Something is causing charging handle / bolt not to close that last 1/8 of a inch every time.
Could really use you guys help in this. Need a list of all the things I need to Try to do including giving up. Ha ha. Thanks. Marty

Sounds like something is dragging on the bolt. You may need to file something down. You can take a marker or removable paint and cover part of the bolt and you may see where it is dragging by where the paint has been removed. Also try inserting the bolt without the charging handle to see if it will insert freely. Last take apart the bolt and clean it.

Ok I have been looking at everything. Making a list for my gunsmith. I have not been able to find issue myself. Keep the lists coming. Thanks. Marty

Whose barrel and bolt?  Sounds like you maybe used a bargain basement el-cheapo barrel and bolt.  Bad barrel extension, bad bolt, mucked up chamber, or all three, they would certainly cause your problems.