The Firing Line Forums - View Single Post - Cartridge Resizing .223 to 300 Blackout/300 Whisper

GrandpaBear · April 9, 2013, 10:19 AM

Getting in to the 300 Blackout/300 Whisper (300 B/W) on my AR-15 platform and I was wondering about converting a barrel of 5.56 once fired to the 300 B/W so I can have more fun. Also, with all the crap coming out of Washington, I want to put in a store of brass and 5.56 is the most prevalent once-fired brass available.

I expect that it takes four procedures, anneal, trim, form, and trim to length. I assume this because the 7.62mm bullets are a lot longer than are the .223/5.56 bullets.

I have also read where the 300 Whisper for the TC was originally made from .221 brass. Since one of the selling points of the 300 Blackout is that the standard BCG for the 5.56mm is usable without modification, I assume that I can use the 5.56 brass as easily.

April 9, 2013, 10:19 AM	#1
GrandpaBear Junior Member Join Date: August 11, 2012 Location: Heading to Seattle area of WA Posts: 4	Cartridge Resizing .223 to 300 Blackout/300 Whisper Getting in to the 300 Blackout/300 Whisper (300 B/W) on my AR-15 platform and I was wondering about converting a barrel of 5.56 once fired to the 300 B/W so I can have more fun. Also, with all the crap coming out of Washington, I want to put in a store of brass and 5.56 is the most prevalent once-fired brass available. I expect that it takes four procedures, anneal, trim, form, and trim to length. I assume this because the 7.62mm bullets are a lot longer than are the .223/5.56 bullets. I have also read where the 300 Whisper for the TC was originally made from .221 brass. Since one of the selling points of the 300 Blackout is that the standard BCG for the 5.56mm is usable without modification, I assume that I can use the 5.56 brass as easily.