Neck up or down?

[Warpt762x39]

In my research for potential firearms purchases for the (hopefully) near future, I decided that I want a bolt action rifle in .260 Remington.

It will only be for the range and as a personal challenge to squeeze every bit of accuracy out of each of the rifle, ammunition and myself.

I have noticed that .260 ammunition is kind of hard to come by and it is rather pricey. With that piece of information I have decided that the .260 bolt gun I buy will be fed only handloads.

After that decision I have found another small problem. .260 brass isn't all that common. Bullets are easy to find because of the 6.5x55mm Swedish Mauser rounds.

I have learned that the .260 Remington case is the same basic case as the .243 and .308 Winchesters. The new piece of info that I need is in regards to resizing brass.

Is it easier to neck down the .308 brass or neck up the .243 brass?

I can't recall ever reading any information on the pros and cons of necking either up or down. Any info would be greatly appreciated.

On a side note I had been researching a wildcat round with the same basic problem but in .25 caliber. Anybody have info on the .25 Souper?

[mauser]

The actual sizing is really easy, no more effort than sizing a case of the proper caliber.
I'd personally opt for sizing up the .243 brass.
When you size down a .308 case you're making the diameter .044" smaller, when you size up a .243 you're making the diameter .017" bigger, a lot less of a change.
You have to pay attention to the neck thickness when you size down, the extra brass has to go somewhere and that somewhere is the wall thickness of the neck. If the neck wall is too thick it can generate dangerous pressure by holding the bullet too tight when chambered unless your chamber is loose enough to allow for the extra thickness. The neck can be turned or reamed to proper thickness if needed, but that's an extra step thereby making it easier to use .243.

[Tomcat088]

What Mauser is saying is correct, but I do want to bring up one point. Just because something is easier, does NOT mean that it's "better"; it will all depend on your application. Sometimes when you size up you will be losing some consistency in the brass and you will add a bit of stress to it. When you size down, you have plenty of extra brass to work with, as mention. When you turn the necks down, you will have a more consistent neck that doesn't have the same stress in it that necking up can cause. You can always take metal off, but it's not too easy to add it back on. Just something to consider, sorry that it's not a direct answer.

[mauser]

What Mauser is saying is correct, but I do want to bring up one point. Just because something is easier, does NOT mean that it's "better"; it will all depend on your application. Sometimes when you size up you will be losing some consistency in the brass and you will add a bit of stress to it. When you size down, you have plenty of extra brass to work with, as mention. When you turn the necks down, you will have a more consistent neck that doesn't have the same stress in it that necking up can cause. You can always take metal off, but it's not too easy to add it back on. Just something to consider, sorry that it's not a direct answer.

Excellent point Tomcat.
I was focused on this part of the OP:

Is it easier to neck down the .308 brass or neck up the .243 brass?

and I glossed right over this part:

It will only be for the range and as a personal challenge to squeeze every bit of accuracy out of each of the rifle, ammunition and myself.

I have noticed that .260 ammunition is kind of hard to come by and it is rather pricey. With that piece of information I have decided that the .260 bolt gun I buy will be fed only handloads.

If the goal is really to squeeze every bit of accuracy of everything then you would be better served by sizing down .308.

If you don't already have the tools to turn or ream the necks I'll suggest that you look seriously at the Forster case trimmer. As well as being an excellent tool for trimming to length, it's also (with the additional attachments and tooling) an excellent tool to ream the inside and/or turn the outside of the necks.
There are other tools on the market to do the same jobs but I can't give you an opinion on any except the Forster. I have one and I like it a lot, I have no desire to try any other.

[hipwr260]

I have had some luck necking down 7mm-08 brass. I had gotten some from a friend who didn't reload so price was't an issue.

[WVBob]

If you want new brass, Midway has it. Norma for $22.99 for 20, Remington $44.99 for 100. I understand wanting to try to "make" your brass. But you will have neck issues any way you go.

[Bama Man]

In my research for potential firearms purchases for the (hopefully) near future, I decided that I want a bolt action rifle in .260 Remington.

It will only be for the range and as a personal challenge to squeeze every bit of accuracy out of each of the rifle, ammunition and myself.

I have noticed that .260 ammunition is kind of hard to come by and it is rather pricey. With that piece of information I have decided that the .260 bolt gun I buy will be fed only handloads.

After that decision I have found another small problem. .260 brass isn't all that common. Bullets are easy to find because of the 6.5x55mm Swedish Mauser rounds.

I have learned that the .260 Remington case is the same basic case as the .243 and .308 Winchesters. The new piece of info that I need is in regards to resizing brass.

Is it easier to neck down the .308 brass or neck up the .243 brass?

I can't recall ever reading any information on the pros and cons of necking either up or down. Any info would be greatly appreciated.

On a side note I had been researching a wildcat round with the same basic problem but in .25 caliber. Anybody have info on the .25 Souper?

The .25 "souper" you have heard of is probably the 250 Humdinger, found in the book, Cartridges of the World.
It is a .243 necked to .257, with minimum body taper and a 45 degree shoulder angle which is similar to an Ackley shoulder.
The case is easily made by necking to .257 and fire forming.

[Warpt762x39]

The .25 "souper" you have heard of is probably the 250 Humdinger, found in the book, Cartridges of the World.
It is a .243 necked to .257, with minimum body taper and a 45 degree shoulder angle which is similar to an Ackley shoulder.
The case is easily made by necking to .257 and fire forming.

Nope. The .25 Souper is an actual round. It's also known as the 25-308. It's a .308 case necked down to .25 caliber. That's it. It was named the Souper in the late 50s or early 60s.

The .25 Souper was originally developed by P.F. Lambert of Washington, D.C., according to Speer’s Reloading Manual for Wildcat Cartridges (Number 4), published in 1960

I read an article on it a few years ago and thought it would be something interesting to try at some point. The .260 Remington would be the same kind of thing but easier to procure the appropriate dies and a barrel.

Heck there's even match grade ammo in .260 Rem for me to compare against.

I plan on staying away from any type of improvement of any round I handload. I try to stay away from overly complicated extra steps.

Norma brass is available for the .260 but it's not as common as .243 or .308 brass. I've heard that the Remington brass for the .260 isn't exactly uniform in thickness. This will be my accuracy chaser so inconsistant brass is something I want to stay away from.

If you neck down the .308 to .260, how much "extra" brass is there at the mouth area? Couldn't that be solved with trimming the case mouth a bit before resizing?

[Flash]

Nope. The .25 Souper is an actual round. It's also known as the 25-308. It's a .308 case necked down to .25 caliber. That's it. It was named the Souper in the late 50s or early 60s.


If you neck down the .308 to .260, how much "extra" brass is there at the mouth area? Couldn't that be solved with trimming the case mouth a bit before resizing?

"Trimming" refers to "case-mouth trimming", that is, shortening (length) of the entire case by trimming length off at the case mouth

"Reaming" refers to removal of brass (thickness) from the inside of the neck area by use of a reamer, a bladed type tool

"Turning" refers to removal of the brass (thickness) of the neck area by taking it off the outside


Just definitions, to be sure, but so that everybody should be speaking the same language.

The resizing of brass, "necking down" causes the neck area to become thicker, and depending on how it is done, the neck stretches, to one degree or another. Neck expanding also causes length issues, as the annealing process which makes it easier to reform brass in ways that you DO want also makes it resize in ways you might not want.

Flash

[Warpt762x39]

"Trimming" refers to "case-mouth trimming", that is, shortening (length) of the entire case by trimming length off at the case mouth

"Reaming" refers to removal of brass (thickness) from the inside of the neck area by use of a reamer, a bladed type tool

"Turning" refers to removal of the brass (thickness) of the neck area by taking it off the outside


Just definitions, to be sure, but so that everybody should be speaking the same language.

The resizing of brass, "necking down" causes the neck area to become thicker, and depending on how it is done, the neck stretches, to one degree or another. Neck expanding also causes length issues, as the annealing process which makes it easier to reform brass in ways that you DO want also makes it resize in ways you might not want.

Flash

That's what I was asking about. If you know how much the brass will stretch is it possible to trim some off the case mouth so when the case is resized the brass stretches to fill that slight void instead of not having a place to go and thickening at the mouth.