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Ovenpaa,

I got a new box of Lapua 30-06 Springfield brass yesterday and shortened it by 0.25 inches and necked it down in one pass of the 260 Rem. body-die with no problem!

I've chopped 'em all down now by 0.25 inches but they will need a skim off the neck - my 260 Rem. has a 297 neck which works with a neck-wall thickness of 15 thou. giving 3 thou. clearance - OK for my tactical rifle. Because the necks are now formed from the case body, they are a bit thicker - around 16 thou. - which is a bit close even for 1000 yard BR - so just a light clean-up skim needed.

I've also made a 260 Nett 'go' gauge so I'll chamber the barrel tomorrow - all being well.

Cheers
Vince

Out of interest (and another thread!) What is the run out on your prepped brass at this stage? I hope you are going to post a couple of pictures of the chambering event tomorrow! last time we spoke you had a huge slab of aluminium and were going to machine your own stock from it, what happened to that project? New thread time maybe? You really do need to post up some pictures of your stuff

Ovenpaa,

Sorry - you asked about run-out on the prepped brass.

I wouldn't even check it at this stage as it has been through several stretching and shrinking processes and could be well distorted.

The chamber will however be straight - so one firing will straighten 'em up! My 30 odd cases will be used to run in the barrel and get some idea of load and velocity.

Cheers
Vince

The Gun Pimp wrote:Woody,

Yes, of course, a 30-06 shortened slightly should work as a full-length body die.

I'm going to try this one but I'm wondering - if we made the case from a 30-06 we could keep the neck a decent length.

I love a new project!

Cheers
Vince

Vince,

The .260 INCH is no more than a .260 Remington with the shoulder moved forward 3,5mm, about half the original neck.

For resizing, a standard .260 die can be used, simply set 3,5mm higher in the press.

The mention of a 30-06 or equivalent lenght dies with .473 base is simply to resize the bottom of the case, should the need arise...

Sizing dies are made custom by Redding.

Reamer is listed by Triebel in Germany as the .260 Chombart!:.

To check headspace, we used a standard .308 gauge, simply adding a 3,5mm washer at rear of the gauges.

R.G.C

ovenpaa wrote:I remember you posting this on the OzF site not so long ago and thought it looked like an interesting project. My take on the shortened neck is neck tension, less bearing area must lead to more consistent tension?

Ovenpaa,

I have always been in favor of short necks.

As an anecdote, the first considered round for NATO adoption in the fifties was the .300 Savage, with its short neck. The US thinking heads objected, wanting a long neck as to ensure better feeding in autimatic guns!!! and the .308 Winchester was adopted for this main reason.

Without going into boring technical details on metal working, reworking a case in order to move the shoulder forward eliminate most of the factors leading to metal flowing from the inside ofshoulder to the neck in an irregular manner and forming a bulge at the junction shoulder-inside of neck. This irregular metal flowing of course is detrimental to a good concentricity of the loaded round.

Also:
-A shorter neck allow much better concentric and, as you mention, more cosntant neck tension.
-As mentioned, concentricity is best achieved.
-Every engineer knows that a metallic seal is much more efficient when in reduced surface. This can be noticed by Woody, as the neck remain absolutely clean after firing, no gas leak to allow carbon deposit (and unfortunaltely indenting too to form an abrasive coat acting to help wear the neck diameter i the barrel) on the neck surface.

Fire-formed .260 Rem or .243 Win cases can be used, but I recommended Woody to use .308 as, as he mention, it is easier to get and fire-form, and the metal in excess at the neck allow reaming and neck turning. Reaming (to minimal) just enough to eliminate any inside neck irrehularities, and finally neck turning to match to the chamber.

R.G.C

woody_rod wrote:Mr Gun Pimp, it might be more prudent to just ask rather than make guesses.

The Gun Pimp wrote:You are correct - a longer neck would be better.

Well, actually, this is not correct. Ovenpaa has it thought out, as Laurie Ingram did. The longer neck of most brass is simply because others did it that way, and rough handling for military calibers, no other reason to have a longer neck.

The neck tension is the one thing that got me when I first loaded this round. I have pulled a bullet from the first case at least 10 times, it still seats and holds the bullet. I have never seen this with a longer neck.

Going further with the metallurgical theory (RGC can jump in here), the design of the short neck also has a few other positive influences. The main one is that the shoulder being more involved with the neck tension, and that the front end of the neck is very close to the shoulder. Even with the proper size inside the neck, the 260 INCH has a lot more neck tension than one with a longer neck. The short neck just does not seem to get to the elastic limit of the brass material - not sure why.

The other main positive is that the neck seals very well in the chamber. There is very little carbon on the outside of the neck, which is always prevalent on our other cases.

I had not rread this post before my reply to Ovenpaa..... Strange simiarities....

R.G.C

ovenpaa wrote:

woody_rod wrote: Well, actually, this is not correct. Ovenpaa has it thought out, as Laurie Ingram did. The longer neck of most brass is simply because others did it that way, and rough handling for military calibers, no other reason to have a longer neck.

The neck tension is the one thing that got me when I first loaded this round. I have pulled a bullet from the first case at least 10 times, it still seats and holds the bullet. I have never seen this with a longer neck.

It will be interesting to read RGC's views on this.

Come on Robert, you must have had your breakfast by now!

Ovenpaa,
I even just come back from an excellent Christmas lunch in a good restaurant..The thread has moved inbetween, and, despite my ago no longer aloow 'jumping in', I reply the best I can message to message.

R.G.C

The Gun Pimp wrote:Well Mr woody-rod,

You do your thing and I'll do mine but with regard to neck-length, ever heard of a thing (theory) called 'turbulance point'?

Cheers
Vince

Vince,

Who really knows what happens inside a case in such a short period of time..There is many unverified theories in the fluids mechanic science.

For instance, sharp shoulders are against Venturi theories.... and they are well praised by many (AI, Weatherby), although being a nonsense IMHO.
R.G.C

R.G.C do you mean you prefer lower shoulder angles such as 28-30 degrees instead of the 'improved' 35 degrees some people move to as during the building of wildcats.

Hi RGC,

Very nice to have you on the forum.

I've ended up making my own version of the 260 INCH by running the 260 Rem. reamer in another 0.2 inches and using a shortened (by 0.25 in.) 30-06 Lapua case. Point taken regarding neck-length but I wanted something a bit more robust for 1000 yard benchrest shooting.

Yes - I could use the 260 Rem. die to full-length size but I was afraid it might a) not re-size the bottom bit of the case and b) it might actually bulge the case. Only time will tell.

I've just chambered the barrel this afternoon and prepped all the brass. I will try and shoot it on Thursday - then we will find out about re-sizing.

Cheers
Vince