Originally Posted by dkf
Pull a bullet and measure the diameter with a micrometer. Also look at the amount of crimp on the bullet, should be a slight ring around the bullet with no deformation. Undersized bullet are known to cause stability issues. If the bullets were not Sierras they may be Montana Gold JHPs. Montana Gold usually has quality bullet however their JHP rounds are more for target practice and not SD IMO. Post some pics if you got them.
They're not Montana Golds as they don't have that "gold" color. They almost
look like Winchester 125gr bullets. Will post a pic soon.