Neck wall thickness in 270/300 WSM cases

[Texas]

I am getting ready to order a reamer for a 6.5 WSM. I will be using the 270 WSM case most likely. I already have some Norma brass and the thickness is about .016 in the neck. I typically have my reamers made with a .003 neck clearance. However it would be nice to also be able to try the Hornady brass and also Winchester. Does anyone know what the thickness of these cases are in the neck? I don't want to get a neck diameter that will only allow me to try one brand of brass. If anyone has the neck wall thickness of the Winchester brass and Hornady it would help with designing this reamer. Thanks.

 

[ballistic64]

.014-.015 on new WW 300 WSM brass that I have.

 

[17VLD]

I use 300WSM brass for my 6.5 WSM and the Win cases I have are .014"-.015" also
but I turn mine to .011" an awesome cartridge.Retumbo is your friend in this case.
Matt

 

[Texas]

Thanks for the feedback. Sounds like I will be able to use any of the manufacturers brass with the dimensions I have in mind.

 

[L.Sherm]

Texas, my 270WSM brass that i am using for my 6.5WSM is running .016-.017 I have to turn about .003 off to get a loaded round .294. My chamber is a .297, My brass is about 6 or 7 years old so i don't know if the newer stuff is thinner

 

[dkhunt14]

When you neck it down it will get .001 thicker. Matt

 

[Kyle Schultz]

My virgin 300WSM brass ran 0.0155" to 0.0158". Walls thickened when I necked down to 7mm. Rather than shoot for a specific thickness, I turned in stages until I achieved a total "clean up" of the neck. In my case, loaded necks measuring 0.313". That implies my turned necks are +/- 0.0145".

With that dimension set, I spec'd my reamer for 0.316" which gives me a 0.003" clearance.

I know momentum is building to open up more neck clearance than the old 0.002-0.003" standard; especially in the larger calibers. If I decide to head that direction, all I need to do is thin the necks a little more. No big deal.

It probably deserves a separate thread but I'm wondering if the improved precision that folks are seeing is really a consequence of more consistent neck tension resulting from a thinner neck wall rather than just the consequence of more neck clearance. Said another way, would a 0.304" loaded 7mm round (0.010" neck wall thickness) in a 0.307" neck shoot better (or worse) than a 0.313" (0.0145" neck wall thickness) loaded round in a 0.319" neck? I'm guessing it might shoot better.

 

[dkhunt14]

My virgin 300WSM brass ran 0.0155" to 0.0158". Walls thickened when I necked down to 7mm. Rather than shoot for a specific thickness, I turned in stages until I achieved a total "clean up" of the neck. In my case, loaded necks measuring 0.313". That implies my turned necks are +/- 0.0145".

With that dimension set, I spec'd my reamer for 0.316" which gives me a 0.003" clearance.

I know momentum is building to open up more neck clearance than the old 0.002-0.003" standard; especially in the larger calibers. If I decide to head that direction, all I need to do is thin the necks a little more. No big deal.

It probably deserves a separate thread but I'm wondering if the improved precision that folks are seeing is really a consequence of more consistent neck tension resulting from a thinner neck wall rather than just the consequence of more neck clearance. Said another way, would a 0.304" loaded 7mm round (0.010" neck wall thickness) in a 0.307" neck shoot better (or worse) than a 0.313" (0.0145" neck wall thickness) loaded round in a 0.319" neck? I'm guessing it might shoot better.

It could be true that the thinner necks give more consistent accuracy because of neck tension. If you look at the 6 PPC game they turn to really thin necks in their tight chambers. But then they also don't anneal and in a match they would get harder as they fire them a bunch of times. I tested a 6MM Dasher at 1000 yards and went from .001 to .004 neck clearance and saw no difference in accuracy. But this was a .266 neck so they are pretty thin (.010 wall .003 total clearance) to begin with. I hear guys in the F-class saying that in cartridges like 284 they seem to be more accurate with more clearance. Another thing is every cartridge I ever necked down the case got .001 thicker. If the thinnest part of the neck was .015 it went to .016 and if the thickest part was .016 it went to .017. I would rather do a tight neck and turn. I just believe it makes more consistent ammo. It centers the bullet in the case and makes neck tensions more consistent. Matt