In order to participate in the GunBroker Member forums, you must be logged in with your GunBroker.com account. Click the sign-in button at the top right of the forums page to get connected.
Options
5.56/300aac rim size help
varian
Member Posts: 2,250 ✭✭✭✭
a friend of mine is having some problems with reloading 300aac made from military brass. he told me the brass would not properly fit the shell holder. looking at the problem brass you can see the rim diameter is smaller than normal. the rim measures approx. .358. my reference material says .378 is spec. In the batch of brass he bought there are quite a few pieces that are this diameter. can someone here shed some light on this please.
Comments
Sounds like the brass is badly out of spec. Not a lot you can do with it being .020 under size. It may not even get hooked enough by the extractor to eject the empty.
found these small rims on both wcc and lc military brass, not sure its a defect but dont know why they are that much smaller
Just an FYI, I grabbed a couple 5.56, and measured the rim. Both LC, one dated 2008, and the other 2015. The '08 measures .376", and the '15 measures .375".
If you are turning .223-5.56 brass into 300AAC you will need to turn the necks as most of them will be too thick to fit the chamber after cutting them down and opening the necks up. BTDT got to pull a few hundred down and neck turn them. ALWAYS load five and check for fit when changing one caliber to another.
Neck thickness is critical.
Try another brand shell holder to see if that helps you. RCBS has always worked for me but Redding or Lee might fix your issue too.