Ream or Turn Case Neck?

[RG1911]

I've been contemplating converting Lapua .308 brass to .260Rem and possibly .284Win to 6.5-284.

When Precision Shooting and its predecessor were still published, I thought that I read that when you reduced the neck diameter, you needed to ream the neck. Is this still the prevailing thought?

I have all the neck turning equipment, but no neck reamers (and not sure who would carry them).

Thank you, Richard

[BK7saum]

Depending on your chamber you may not need to ream or turn. If a factory chamber, you likely won't. What is the diameter of a fired case neck? If loaded ammo is 0.002" smaller, then you should be good. That would be about 0.003" neck clearance. What are your measurements on fired necks and loaded cases now with the brass you have.

[Blkpwdrbuff]

RG 1911,
The only case I neck ream is my .17 Javelina. On some of my cases I get a "doughnut" at the neck/case junction and ream to remove it.
Check your brass and see if you have that problem. If not, don't ream.
Blkpwdrbuff

[M-Tecs]

Reaming is quicker but turning gives better results. When necking down necks do get thicker and that may or may not be an issue. In my experience neck wall thickness tends to get more uneven. For me reaming is reserved for "doughnut" issues that are hard to resolve with turning.

[GBertolet]

Turning when necessiary, gives much more consistent results. The case is turned concentric with the inside of the neck. The pilot insures this. The neck thickness is even all the way around. In almost all cases, this is more desirable. You may not even have to ream, or turn, unless you want more consistency of neck diameters.

[Preacher Jim]

When pulling down from larger caliber to smaller I ream to remove donut that can form.

[RG1911]

Thanks to all for the information. One reason I asked is because both the 260Rem and the 6.5-284 have tight necks, so expecting the neck to become thicker, I'm preparing for whatever I might need to do. As I mentioned, I already turn the necks for concentricity and to ensure there is sufficient room for expansion. The 260 is particularly fussy since it's a semi-auto.

Concerning reaming donuts, is Brownell's the normal source for reamers? Do you buy a reamer of bullet diameter or ...?

Thank you, Richard

[M-Tecs]

It depends on how you are going to ream. An RCBS reaming die? Wilson type tool? Some of the other type case trimmers? Drill press?

[country gent]

I normally neck turn when needed. On one wild cat I actually do both. I neck rem in a die with the neck supported to clean up then neck turn to size for the fitted neck in the chamber. This gives very accurate neck wall thickness. On this case necks will thicken to around .015 - .017 since the new neck is formed mostly from the shoulder on the original case.

I ream for clearance and to get a even surface. I neck turn for fitted necks in tight necked chambers. For reaming supported in a die measure the necks ID in the die subtract the this dia frombullet dia and then subtract another .001 - .002 for tension. In this way you die will size and not over work brass

[RG1911]

It depends on how you are going to ream. An RCBS reaming die? Wilson type tool? Some of the other type case trimmers? Drill press?

Learn something new every day. I had never heard of a reaming die. I do have RCBS, Lyman, and Forster case trimmers, and a fine old drill press.

Thank you, Richard

[RG1911]

I normally neck turn when needed. On one wild cat I actually do both. I neck rem in a die with the neck supported to clean up then neck turn to size for the fitted neck in the chamber. This gives very accurate neck wall thickness. On this case necks will thicken to around .015 - .017 since the new neck is formed mostly from the shoulder on the original case.

I ream for clearance and to get a even surface. I neck turn for fitted necks in tight necked chambers. For reaming supported in a die measure the necks ID in the die subtract the this dia frombullet dia and then subtract another .001 - .002 for tension. In this way you die will size and not over work brass

Thank you!

Richard

[B R Shooter]

When pulling down from larger caliber to smaller I ream to remove donut that can form.

The opposite happens. When you neck up, part of the shoulder brass ends up in the neck. Case in point is the very popular 30BR. You open 6MM brass to 30 caliber, the shoulder is at the bottom of the neck, and is very easy to see with the naked eye.

I have necked down 6BR cases for 22BR. I never got a doughnut, the neck gets thicker and longer.

[indian joe]

The opposite happens. When you neck up, part of the shoulder brass ends up in the neck. Case in point is the very popular 30BR. You open 6MM brass to 30 caliber, the shoulder is at the bottom of the neck, and is very easy to see with the naked eye.

I have necked down 6BR cases for 22BR. I never got a doughnut, the neck gets thicker and longer.

Yup! thats what I have with 348 cases necked up to 45/75 - little donut where the crease of the old shoulder was - not a problem until I load longer boolits (405 grain) then the donut interferes with the boolit .

[B R Shooter]

Yup! thats what I have with 348 cases necked up to 45/75 - little donut where the crease of the old shoulder was - not a problem until I load longer boolits (405 grain) then the donut interferes with the boolit .

Me too! I shot thousands of 30BR J's with no issue, and started using the same brass shooting cast. Well I had to seat the heavier cast deeper, and there was the doghnut! Took me a match to realize what was going on. Since I had the doughtnut inside, I used my .3105" chucking reamer and ran that down the fired necks, worked very well.