Reamer and dependent brass

[UndFrm]

I am looking at a reamer and it specifically mentions Lapua brass (no neck turn). It also mentions "Peterson brass require a neck dia xxx for no neck turn".
Why is a reamer specific to a brass brand and I am not sure why neck turning is even mentioned here?
New to reloading and I have only heard of turning neck if it gets too thick.

Thank you

 

[Chris1972]

Each manufacturer of brass makes their brass a different thickness. So if Lapua brass is say .014” at the neck and you’re loading a .284” bullet, then the loaded cartridge will be .312” at the neck. The reamer must be larger than the neck of the loaded brass, but you want it as close as you can get while still allowing the brass enough space to expand slightly when the bullet is fired. Theoretically the tighter the neck, the better the bullet is aligned to the barrel.


Basically if the reamer is set up for one brass specifically, a thicker brass will be too tight and need its neck turned.

I’ve never saw this written so take it for what it’s worth. My opinion.

 

[UndFrm]

I'll bump this up instead of creating a new thread.
There's a reamer up for sale locally by Manson and the description says that it's designed for Lapua. It mentions "Alpha may need .274 dia. for no neck turn". I'll be using the Alpha brass.
Does this mean, if I get a FL sizing die and put a .274 bushing, the reamer would work as it should? Or, should I spend double the $ and get one new that specifically mentions Alpha?

Thank you

 

[KnowNothing256]

I'll bump this up instead of creating a new thread.
There's a reamer up for sale locally by Manson and the description says that it's designed for Lapua. It mentions "Alpha may need .274 dia. for no neck turn". I'll be using the Alpha brass.
Does this mean, if I get a FL sizing die and put a .274 bushing, the reamer would work as it should? Or, should I spend double the $ and get one new that specifically mentions Alpha?

Thank you

Reamer neck diameter and sizing die neck diameter aren’t really related. Sizing dies (however you set your neck tension, whether bushing or mandrel or expander ball) set the neck dimensions BEFORE the bullet is seated. The reamer/chamber neck diameter needs to be bigger than the cartridge AFTER the bullet is seated, and that cartridge neck diameter depends on the brass thickness, as described earlier.

So, to answer your question, no, a 0.274 bushing won’t automatically make it work. It’s warning you that Alpha brass is likely too thick for that reamer’s neck dimension. You want a different reamer, Lapua brass, or neck-turned Alpha brass.