I got a nice 284 cal. Barrel from M1 Tanker I'm trying to decide whether or not to make a 280A.I or 7mm Gibbs. My friend has a 7mm Gibbs and loves it and he said I should go that route but it is the cost of dies that has me against it. If I go the A.I route dies aren't that expensive. I don't want a 7rem mag, I already have a 284 Winchester and I'm not a big fan of the 7mm-08. what do you guy's think. I'm building it on a 98 mauser.

The case forming involved in the Gibbs type designs is a pain.

Save yourself a lot of wasted time and if you need magnum velocities then get a magnum!

323
If your still interested theres another route to go......... Hawk Cartridges. Basically a 06 improved case with about 10% more capacity. They sell preformed cases and dies as does Huntington. They come in all the popular bullet dia. from .243 to .411. Just an idea. Z-Hat is the gunsmith.
Good luck on it

How much do they want per case?
And anyway, the best they do isa come colse to Rem Mag.
Ifyou don't like the 7mm-08, have a 284 and don't want a Rem Mag, then IMHO, you got yourself the wrong barrel!
The Rem Mag is an exccelent case for the caliber. If you like, take a look at the Dakota. The dies and cases can be pricy, but it might be up your alley.
The 280 AI won't do anything your 284 Win can't do.
Nothing wrong with having two guns in the same chambering. Maybe get another 284 with a really long barrel....

The .280 AI dies are cheaper and more available. A true wildcat junkie doesn't worry about such trivial matters. All that aside. The Gibbs case doesn't really offer that much case capacity over the .280AI to warrant the extra expense of custom dies. It comes to about a >2.0 grain difference which may get you about 50fps. If it were my decision (that is what you asked for) I would go with the .280AI. The .280AI WILL do things the .284win won't do. We are only talking 100 fps tops. But that is exactly why we wildcat. Now for the mauser action. The magazine will need to be lengthened to fully enjoy the benefits of the .280 case. Feed rails and ramp may need to be opened a bit for the improved case dimensions. For the standard .280 Rem case there is no feed rail adjustments needed but I would lengthen the mag. But like I said, wildcat guys don't worry about such trivial matters.