I'm about to start loading for this classic Mod 100 .284 carbine. I've taken it down, cleaned 45-50 years worth of gunk out, recovered the obligatory screws and springs that vanished during disassembly, and restored to working order.

I have a goodly stock of Horn 139 SP's laid up and H4350, H4831, H414, Big Game and Hunter on hand.

Does anyone have experience with this rodeo? If so, let's hear it. If not, Campfire Guesspeculation can't hurt.

GE

Did you lose a bet?

My first deer rifle I bought was a model 100 in .284 and I killed my first 2 deer with it in 1967. I loaded it with Speer 130 or Winchester 150 bullets because they were the closest to factory load weights. I was advised to use IMR-4350 or H-4831 powder, back then we weren't confused with so many choices. Anyway, my notes says I loaded 54 grains of 4831 with the 150 which gave 1.25" 3 shot groups or 54/4350 for 1" groups. The 130's powder charge was 55 grains of 4350 for 1.25" groups with which I killed my first 2 deer.

I wouldn't say I "lost a bet", maybe it's that I want to justify three hours spent in my garage hunting for a two screws and a spring ...

GE

Keep in mind that you oal is limited by the inside dimension of the magazine.
The 139 Horn should work just fine, but you have to shoot it to know.

Guessing that a middle range load of 4350 behind the Hornady bullet would be a place to start ....

I have a 284 in a Browning A-bolt, and a mdl 100 in 308. The Browning is incredibly accurate, the 100 shoots pretty good, but make sure you FL size. The 284 is an awesome round, just limited in the mdl 100 platform. You have to shove the bullet deep to fit the mag. You will probably not be able to wring all the performance out of the mdl 100 due to shoving the bullet in so far. I use IMR4350 in my 284, I have tried up and down the scale a bit (H380, H414, AA4350) but IMR was the best. Of course your rifle will be different. Good luck.