The Firing Line Forums - View Single Post - .223 Once-fired brass, neck dia. too small

**Unclenick** · January 27, 2012, 05:14 PM

I'm pretty sure it says somewhere on the Top Brass site that they roll size the brass. This means it is rolled between two carefully spaced plates that have the correct exterior case profile. It has the advantages that the plate profile can be made to size the head and rim and extractor groove along with the rest of the case, where a handloader's dies do not. A lot of military surplus brass has bent rims from vigorous extraction, so that feature would be valuable in returning it to serviceable condition. It is also a fast sizing method that can be automated. It requires no case lube that would have to be subsequently removed, either. Just decap and clean the brass to keep the plates from getting scratch up, and run the stuff through.

Roll sizing also may not grow the brass as much as a handloader's sizing die does because it acts on the shoulder and sides of the case simultaneously, where a handloader's die narrows the case first, pushing the shoulder forward, then pushes the shoulder back, causing brass to squirt into the neck area. By holding the shoulder down as you narrow the body, as much brass may flow down as up.

I don't know how they incorporate trimming into their process. Expansion, if they were to do it, would require adding an operation and cost.

Lockinload,

Assuming equal quality, flat base bullets are almost always easier to get best short range accuracy with. What you can do is use a Lyman M expander die to get the bullet sitting upright for seating. You then adjust the seater die so the crimp profile built into it just closes the expanded portion back flat against the bullet.

January 27, 2012, 05:14 PM	#14
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,061	I'm pretty sure it says somewhere on the Top Brass site that they roll size the brass. This means it is rolled between two carefully spaced plates that have the correct exterior case profile. It has the advantages that the plate profile can be made to size the head and rim and extractor groove along with the rest of the case, where a handloader's dies do not. A lot of military surplus brass has bent rims from vigorous extraction, so that feature would be valuable in returning it to serviceable condition. It is also a fast sizing method that can be automated. It requires no case lube that would have to be subsequently removed, either. Just decap and clean the brass to keep the plates from getting scratch up, and run the stuff through. Roll sizing also may not grow the brass as much as a handloader's sizing die does because it acts on the shoulder and sides of the case simultaneously, where a handloader's die narrows the case first, pushing the shoulder forward, then pushes the shoulder back, causing brass to squirt into the neck area. By holding the shoulder down as you narrow the body, as much brass may flow down as up. I don't know how they incorporate trimming into their process. Expansion, if they were to do it, would require adding an operation and cost. Lockinload, Assuming equal quality, flat base bullets are almost always easier to get best short range accuracy with. What you can do is use a Lyman M expander die to get the bullet sitting upright for seating. You then adjust the seater die so the crimp profile built into it just closes the expanded portion back flat against the bullet. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle Last edited by Unclenick; January 27, 2012 at 06:10 PM.