I have a ULA Model 20 in 284 Melvin built for me in 1990 that I have drug all over North America. I'm pretty sure it came with a 2.75 inch magazine box because I always had to watch the cartridge length because of that. When I sent it in 4 or 5 years ago for a face lift I had Melvin put the 3 inch magazine box in the stock at that time.
When I bought the rifle I had Superior Ammunition load me up about 20 boxes of 284 140 grain Nosler Partitions of which I still have a couple left. All the cartridges are just a shade under 2.75" long for that reason. Had to shove that Partition quite a ways in the case on top of the 55 grains of IMR 4350 to keep it under 2.75".
That is interesting. You got me curious, so I measured a 20 built in 1988 - 3.0” box.
