Remington Green Box Ammo

At auction I recently managed to pick up 3 boxes of Remington ammo with 174 grn FMJ bullets. All the boxes were still glued shut, and the ammo inside is definately brand new, factory fodder. On looking at them I see that the rounds seem to have noticably longer necks than any 303 ammo I've seen before. Does this bode well for reloading the cases?
Before anyone chimes in, no, they aren't 30-40 Krag in the wrong box. Head stamp is "303 Brit" and the neck is still a good bit shorter than Krag ammo. It just looks "a bit funny".
Obviously, these aren't a current Remington offering, does anyone know when Remington stopped producing this ammo?

The Remington/UMC ammo is good stuff. The brass is OK although probably not as good as military production. They still produce it from time to time. I'd stock it if I could buy it by the case but it hasn't been on the market here for quite some time, at least not with the few distributors I use.

The Remington/UMC FMJ still shows up regularly on the shelf at our Calgary "Bass Pro-shop". It goes fast and they could probably sell 10 times as much as they get. Suffice to say that I now have enough of the brass to last a lifetime and have found no problems re-loading it. I don't think I have a rifle it doesn't shoot well in whereas the PRVI equivalent with BT's is not so good.

Ridolpho

If it's a flat based bullet, who makes it?
Also, if it's still occasionally appearing on shops' shelves, does that mean it's still in production?
I've also got 18 rounds of the old Remington ammo with the 215 grn bullet, for if I ever get the chance to go after a moose.

If the case is normal length the shoulders are pushed back further than what you are used to seeing.