My project - 260 INCH

[woody_rod]

Hello all,

Here is some stuff on the 260 INCH I am working on. It has history from the UK, being initially conceived by Laurie Ingram, and later involvement by Robert Chombart. I have now taken over its development in memory of Laurie.

The chambering is based on a 308 case necked down to .264" and the shoulder blown forward 3,5mm. This leaves a short neck, but it actually works extremely well. I have about 200 rounds through my F Open rifle now in this caliber, and is starting to really get the job done. I will post a pic of my FO rifle later.

[woody_rod]

Performance so far:

The 260 INCH pretty much matches the performance of the 6,5 x 284 chambering. I am currently running 48 grains of AR2209 to get 3050 fps, and could go up to at least 52 grains of the same powder, but I don't see the benefit. I have spent most of my shooting career (5 1/2 years) shooting 308 in TR. It is weird adapting to the 260 as it shoots so much flatter than the 308.

I bought a set of inside neck reamers for all our calibers (224, 264 and 30), and now ream the necks of the 264 in particular, as the neck being smaller diameter gives a thick neck wall. I use my 308 seating die without any modifications, so the bullet is in free space, with the case and the bullet tip being held by the die. it works extremely well with very small runout.

RGC had the reamer, so he donated that to the project. It is a custom made unit for the 260, to include the short neck etc. I use my 260 rem roughing reamer to do the chamber to start with.

[The Gun Pimp]

Woody,

Looks very interesting. I'm a great fan of the 260Rem. - usually made by necking-up 243 Lapua brass but your round gives a useful increase in powder capacity - your 3050fps velocity will be with the 139/140 grain bullet?

What about a full-length die? Have you managed to modify/use an existing die or did you have to make one?

I'm looking to re-chamber a 6.5-284 for a buddy in 260Rem. but this could be just the cartridge.

Cheers
Vince

[woody_rod]

Woody,

Looks very interesting. I'm a great fan of the 260Rem. - usually made by necking-up 243 Lapua brass but your round gives a useful increase in powder capacity - your 3050fps velocity will be with the 139/140 grain bullet?

What about a full-length die? Have you managed to modify/use an existing die or did you have to make one?

I'm looking to re-chamber a 6.5-284 for a buddy in 260Rem. but this could be just the cartridge.

Cheers
Vince

I am using the Lapua Scenar 139 grain bullet. They are nicely made and half the price of the SMK, which I believe are a bit out of date these days. The scenar is so accurately made, I found very little differences in weight or ogive length etc.

The main reason I use 308 brass is our state association buys 308 Lapua brass by the thousands, and we get it cheap. Have never seen a 243 Lapua case here... The only trick is to thin down the neck, otherwise it is very simple. Fire forming was done using the BR brass technique I read about on 6MMBR site, and elsewhere. This is done by sizing the neck back only as far as is needed, and to keep the case back hard against the bolt face (the remaining 30 cal neck acts as a false shoulder). I lost no cases doing this. Although other methods were suggested, I found using a proper load and the actual bullet to be used was the only way to fully form the case.

The 260 INCH has a lot more capacity than the 308W/260R. I am using a powder that is more coarse than typical for the 308, and it holds about 15% greater quantity of the same powder. It is almost identical to the 6,5 x 284 in capacity.

I obtained the FLS die from Laurie Ingrams Son, it is the only one in the world as far as I know. Made by Redding (I think) as a one off. After fire forming, I used the FLS die initially to make sure all the cases were the same. This was after neck reaming. I now use a Hornday custom neck sizing die, which works very well.

I am told the 270 or 30-06 FLS die will work as a body/bump die, as it won't touch the neck, and has the same body taper and is longer than the 308. Yet to try this, but might be useful.

Any sort of std die won't work, as the neck is too short. I also have a LEE collet neck die, which with a 3,5mm spacer could also work just for sizing the neck.

[woody_rod]

This is the rifle in its initial guise. It is now on a laminated stock and has Warne QR rings on the scope. The barrel is parallel 1,25" x 31" 8 twist Pac Nor 5 groove super match grade. Scope is Weaver T24 with fine cross hair 1/8 MOA dot. Trigger is the standard CG UNI unit made by Tom Myers in the USA. As used by all CG INCH actions. This stock is a locally made BDG unit, in anodised aluminium.

A 20 MOA rail was initially installed, but I could not get it to zero at short range, so I made another with zero angle - all works good now. There is a lot less elevation required than typical 308's etc.

The rifle with the laminated stock wasn't balanced too well due to the heavy barrel, so I added a 1kg steel bar inside the butt, held in by the butt plate. it is just under 10 kgs max weight for F Open (22 pounds). Recoil is very moderate, and less than a 308 using 155 grain bullets.

The stock was changed mainly due to having two other rifles with the same heights being used at the range. My wife and daughter shoot also. We can the use the same rest setup, and not have to move anything much. Saves time, and adds to enjoyment of shooting, rather than wasting time making changes to everything each time we shoot a different rifle. My daugher is 12 and only just started shooting at the club. Neither my wife or daughter were pressured to shoot or become members of the club. they both decided to get involved from their own interest, which is good from a committment point of viiew.

[The Gun Pimp]

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

[ovenpaa]

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?

[The Gun Pimp]

Ovenpaa

You are correct - a longer neck would be better.

With this in mind, I've shortened a 30-06 case and then necked it down to 260 or 6.5m. It holds 54 grains of VitN550 compared to the 260Rem. which holds about 48 grains (to the bottom of the neck).

54 grains is about the useable capacity of the 6.5-284 so it might be quite a potent long range round without being too much of a barrel-burner.

If I could suss out how to post a pic of the case, I would!

Cheers
Vince

[The Gun Pimp]

OK - here's the new case - left std 30-06, middle, std. 260Rem. left, the new wildcat - which I've christened the 260 Net - as it was created on the internet.

Big problem with any new wildcat is the full-length body-die. Dies are slightly undersize so you can't use the chamber reamer to make your die - a new reamer is needed. Then, you need to have your new die hardened - expensive if you have it nitrided.

If you can find an existing die that you can modify - great! Woody suggested the 30-06. This body-die can be shortened easily and although not ideal - as the shoulder-angle is marginally different - it should work when used in conjunction with a 260 Rem. body-die.

A nice project for over Christmas.

Vince

[ovenpaa]

Vince, what stages do you go through to reduce the case length and re form the neck? I is a matter of calculating the final form surface length, trim to length and then bump it through a die or something different? I have necked up and necked down in the past but never significant reduced the length of the shoulder to head length