In an ad for ammunition I read "Reamer must be a no turn neck reamer". Can someone elaborate on this for me?
Gunsmithing What is a no turn neck reamer?
- Thread starter Boatninja
- Start date
Reamer Neck refers to the nearly parallel diameter of the chamber as corresponds to the same parallel portion of the casing ahead of the shoulder.
A “no turn” indicates that the reamer is large enough diameter through there that no normal brass would require being turned and thinned to fit in the chamber.
Lapua, Peterson, and a few others are pretty thick necked brass. Some of that is due to having started with a thicker cup in the first place to get stronger final product, and some is probably by intent, knowing that we will turn a lot of it for match brass anyway.
Peterson, a boutique manufacturer, even goes so far as to offer “fat neck” brass just for this purpose.
A chamber for “all brass”, or a “no turn” should probably generate 3-4 mils of annular clearance with the heaviest brass... ie: Lapua.
A “no turn” indicates that the reamer is large enough diameter through there that no normal brass would require being turned and thinned to fit in the chamber.
Lapua, Peterson, and a few others are pretty thick necked brass. Some of that is due to having started with a thicker cup in the first place to get stronger final product, and some is probably by intent, knowing that we will turn a lot of it for match brass anyway.
Peterson, a boutique manufacturer, even goes so far as to offer “fat neck” brass just for this purpose.
A chamber for “all brass”, or a “no turn” should probably generate 3-4 mils of annular clearance with the heaviest brass... ie: Lapua.
Remember that a “no turn” doesn’t mean you can’t turn. Just that you don’t have to.
A common myth in the practical/tactical rifle world is the only reason to neck turn is to fit a tight neck chamber.
Also, many “no turn” reamers are .002-.003 clearance. Many consider that pretty tight even though it will still chamber. I usually spec .005 for brass that I absolutely intend not to turn. At .003, I would be tempted to skim turn back to .005-.006 clearance.
A common myth in the practical/tactical rifle world is the only reason to neck turn is to fit a tight neck chamber.
Also, many “no turn” reamers are .002-.003 clearance. Many consider that pretty tight even though it will still chamber. I usually spec .005 for brass that I absolutely intend not to turn. At .003, I would be tempted to skim turn back to .005-.006 clearance.
I have ordered two custom "no neck turn reamers"
1) 6mmBR 0.272" neck from PTG
2) 223 Rem 0.250" neck from Manson
They both had some throating adjustments that cost extra.
They both took many moons to arrive.
1) 6mmBR 0.272" neck from PTG
2) 223 Rem 0.250" neck from Manson
They both had some throating adjustments that cost extra.
They both took many moons to arrive.
I go with a .256 neck in a 22BR and a .257 in 22 Creedmoor. Both of those work well for no neck turn.
