Ruger SR556: Cases sticking in chamber
The armorer for my dept bought a Ruger SR 556 about three years ago and it has been trouble free shooting factory rounds.
He has recently started reloading and the cases are sticking in the chamber, so he asked for my advice since he knows I reload. I figured this would be a easy fix since it shoots factory ammo just fine, but the reloads cause problems so my first thought was he is resizing the cases improperly and doesn't have the die adjusted correctly.
He is using a full length sizer and brought the ammo by to test it in my case gauge. His cases fit perfectly in the case gauge and I uses a small base sizer and my cases fit in the gauge too, but both cases stick inside the chamber and require some force to open the BCG while pulling on the charging handle. We tried about 15 rds, some cases will only go about half way into the chamber before becoming stuck. All rounds go into the case gauge and fall free with no force, and chamber into my Colt and BCM without any problems and fall free from the chamber.
This made me think his chamber was dirty so I cleaned it, but it was almost spotless and that did not help the problem. His chamber has no burrs and is polished smooth from the factory. I did not see any visual signs of damage. My only guess is the Ruger has a tight chamber. Is Ruger known to have a tight chamber? Is there anything I am overlooking?
Does anyone know if the Ruger has a true 5.56 chamber, or is it a .223 chamber advertised as a 5.56 chamber? If its a .223 chamber could this be the problem? Whats your thoughts?