I read in an article in Wildcat Cartridges that the 270 Gibbs is not an "Improved" cartridge, but why, how or to what extent it is not "Improved" was not completely spelled out. In this context, I would take the term to mean either that the case can be made simply by fireforming the standard cartridge or that the standard cartridge can still be fired in the "Improved" chamber or both. How do these criteria apply to the Gibbs? Can a standard 270 cartridge be fired in a 270 Gibbs chamber?

Yes, but it's not recommended. The classical definition of the Improved cartridges (the Ackley or RCBS versions for example) includes the fact that the new round can be formed by just shooting the parent case in the chamber. To properly form a Gibbs case, you need to create a false shoulder in the neck area (by sizing the neck first up to the next larger bore size, then down to the poper neck size, but only so far as to create a slight bulge at the base of the neck that the case will headspace on in the Gibbs chamber. You can also single load the cases with the bullet sticking out far enough that it is FIRMLY planted in the lands of the bore, but I find the first method works better for me. I use it in the two Gibbs rifles I shoot, a 240 and a 7mm. FWIW - Dan

In the Ackley since of the word it isn't an improved case. When they speak of an AI or Improved case it means that the headspace is the same as the factory case it was made from. By simply changing the shoulder angle and reducing the body taper . One the KEY benefits of the improved is that you can fire factory ammo in the same chamber.

The Gibbs and many others have the body taper reduced and the shouldr angle increased to increase capacity. However since the shoulder is moved forward you can not safely fire a factory round in the Gibbs chamber. The case MUST be fireformed first. Bt either forming a false shoulder, seating the bullet into the lands etc. Some method has to be added to allow safe headspacing. So the Gibbs is a Wildcat not an improved factory case.

The way I've formed the 280/7mm gibbs is with 12grs buulseye and a case full of cream of wheat and a tissue plug,it has always worked well for me.The gibbs are great cartridges.The 7mm pushes a 160gr @ 3050fps for me with 58grs of RL19

I never did hear of a 270 Gibbs Imp.After the Weatherby 270 Mag,I mean how can one inprove a 270 round?Does the 270 Gibbs out perform the Weatherby 270Mag?