"Since the gauges for the 30.06 and 25/05 (also 280, 270, 35 whelan) are the SAME,"

That's not quite right. The .280 Rem. is a fraction longer to Darwin types cannot load it into a .270. Proper headspace for the .280 would be excess headspace for the 2505..270, 30-06 and .35 Whelen.
Paul B.

Our forefathers did not politely protest the British.They did not vote them out of office, nor did they impeach the king,march on the capitol or ask permission for their rights. ----------------They just shot them.
MOLON LABE