What made my accuracy become horrible?

[KylerB]

After reading all of the replies i think I have it narrowed down to either media left either in the case or possibly the barrel. I believe it was the media because there was some dust build up in the neck of the cases that I brushed out. There was probably a coating of this dust in the whole case. I realized the bad groups shot consistently high which could be caused by the media being stuck in the case and building excess pressure. I have some brass that I cleaned really well with dish soap and water that I'm going to shoot soon to test my theory.

 

[KylerB]

I have found my problem! I trimmed some cases to the exact same length as the ones I shot horribly with and did all of the other reloading procedures the exact same. I tumbled the cases using the same media and noticed a little amount of build up. I washed them in soap and water and dried them well in the oven then letting them sit for a day. I then took compressed air to them to make sure they were clean. I was able to shine a light through the flash hole and confirm there was no media stuck in the case or flash hole. Loaded them up, shot them, and they performed as normal. So I guess the lesson learn for me is too make sure all media is out of the case and flash hole. Thank you to everyone for the input!

 

[ebb]

Glad you didn't need a new barrel

 

[M14AMU]

#1...you're shooting a .270! It ain't 'noted' for winning world championships like the .308 Winchester!

Media??....in the cases???

Did you check that before charging with powder??

DUH?????????????