I am planning on building a 6BR Norma. I do not want to trim necks. There is a little difference in opinion about what size neck to get even if you want a no turn neck. So what I intend to do is to put together some loaded rounds to determine the neck diameter. Then I will have a starting point. What is the consensus on how much clearance there should be between the neck of the round and the neck portion of the chamber for optimum accuracy? For instance, If the loaded round comes out .268 would I want a .272 neck, for a .004 difference, or would I want it tighter? When people turn necks, what is the difference in ammo neck to chamber neck size that they are going for? Are there other issues I am over looking?
Gunsmithing No turn neck size question?
- Thread starter jeffm
- Start date
Re: No turn neck size question?
The OD of the neck is not related to the "Throat" at all.
The OD of the neck is not related to the "Throat" at all.
Re: No turn neck size question?
benchrest guys go down to scary levels.
My F-Class rig and several other rifles run 3 thou clearance - I have .310 loaded rounds on my 7WSM, 7 Dakota (yes I turn necks on both to .013) and a .313 chamber. My 6x47L is no turn but 3 thou clearance.
I prefer no more clearance than 4 thou, but I own all of my own reamers also so I can control the clearance.
JeffVN
benchrest guys go down to scary levels.
My F-Class rig and several other rifles run 3 thou clearance - I have .310 loaded rounds on my 7WSM, 7 Dakota (yes I turn necks on both to .013) and a .313 chamber. My 6x47L is no turn but 3 thou clearance.
I prefer no more clearance than 4 thou, but I own all of my own reamers also so I can control the clearance.
JeffVN
Re: No turn neck size question?
There's the new blue box 6BR brass (approx .268" loaded) and the old paper box 6BR brass (approx .269" loaded). Typically a .272" would be a good no turn neck but, the newer brass may require a .271" neck to have the same clearance but, .272" would work just fine.
You'll need to measure your loaded necks to determine a final neck diameter in the end.
I run a .269" Nk in my 6BR but, that’s a tight neck. I run a .272" in my Dasher as a no turn but, paper box 6BR brass is used.
As far as "How much" I'd have a reamer ground for .0015" per side clearance max over from a loaded round for a BR/F-Class Rifle.
There's the new blue box 6BR brass (approx .268" loaded) and the old paper box 6BR brass (approx .269" loaded). Typically a .272" would be a good no turn neck but, the newer brass may require a .271" neck to have the same clearance but, .272" would work just fine.
You'll need to measure your loaded necks to determine a final neck diameter in the end.
I run a .269" Nk in my 6BR but, that’s a tight neck. I run a .272" in my Dasher as a no turn but, paper box 6BR brass is used.
As far as "How much" I'd have a reamer ground for .0015" per side clearance max over from a loaded round for a BR/F-Class Rifle.
Re: No turn neck size question?
I'm am reading that .003 is ideal and .004 is OK. Thanks for the replies, Jeff
I'm am reading that .003 is ideal and .004 is OK. Thanks for the replies, Jeff
Re: No turn neck size question?
Hi i am running a .271 neck on my 6mmBR and Dasher it works well especialy with the newer slightly thinner Lapua cases.
realy if you go for a .272" neck the world is not going to stop spinning but i have been running the .271" neck for the last 5 years with no problems. i have a rechambered remington VLS that was a factory 243 with the barrel set back rechambered action trued and then barrel cut to 20" it actualy shoots realy well it is amasing what happens when you chamber a barrel properly. i have loaded cases over 20 times with the .271" neck diameter.
Also you say you dont want to trim necks trimming is reducing hte length of the neck so you wont be doing that to start with any way you are thining of turning the necks with a .271" neck you dont have to turn them either andyou can also run Lapua, Remington and Norma brass i run them all in different rifles and the same neck diameter.
Hi i am running a .271 neck on my 6mmBR and Dasher it works well especialy with the newer slightly thinner Lapua cases.
realy if you go for a .272" neck the world is not going to stop spinning but i have been running the .271" neck for the last 5 years with no problems. i have a rechambered remington VLS that was a factory 243 with the barrel set back rechambered action trued and then barrel cut to 20" it actualy shoots realy well it is amasing what happens when you chamber a barrel properly. i have loaded cases over 20 times with the .271" neck diameter.
Also you say you dont want to trim necks trimming is reducing hte length of the neck so you wont be doing that to start with any way you are thining of turning the necks with a .271" neck you dont have to turn them either andyou can also run Lapua, Remington and Norma brass i run them all in different rifles and the same neck diameter.
Re: No turn neck size question?
I bot from Dave Kiff, on his recommendation, a reamer for the new blue box Lapua. .2705 neck 6 br. Works great no turn, loaded at about .2675. No problems at all. One barrel already chambered with it and it is a lazer. .60 throat for up to 95 gr., shooting 60-80 gr great.
I bot from Dave Kiff, on his recommendation, a reamer for the new blue box Lapua. .2705 neck 6 br. Works great no turn, loaded at about .2675. No problems at all. One barrel already chambered with it and it is a lazer. .60 throat for up to 95 gr., shooting 60-80 gr great.
