The cost of factory hunting ammo in traditional deer calibers is all about $30 a box of $1.50 per round. and not coming down. I use 06 and 257 Weatherby for my deer hunts 99% of the time. Haven't bought any factory 06 ammo in 10-15 years, do not recall the last as I do not use the factory much. When I do it is only the 168 grain Winchester Silvertips, that stuff is magic in my gun, killed at least a dozen big deer with it, all one shot events. My gun shoots that stuff into one hole, while my reloads are all under 1 inch, that ammo is just too good in my gun to change.
The 257 is a different story. I love the round, killed maybe a dozen deer with it now, the gun was a retirement gift, actually Bass Pro Gift card. Botton line Vanguard and it also shoot under 1/2 inch with factory or reloads, does not matter, anybody can shoot dimes size groups with that one. Problem is that Weatherby ammo is $50-$80 a box. Nuts, simple solution. Reload. I also make all my cases from 7mm mag. Just one stroke in the sizing die and poof you have a new case. It is 1/16th shorter than factory ammo but it makes zero difference, I have tested them side by side, no change in velocity or accuracy. Reloads are then 45 cents powder, 9 primer and 30 bullet, or 84 cents or $16.80 a box, certainly better than $50 or more.
I shoot more rifle rounds than most deer hunters just because I like to shoot those guns. I just loaded a pile of 257 ammo with 87 grain bullets at 3,750 fps. Do not plan on shooting many of those for fear of barrel wear but would like to catch some coyotes out at 300 yards or more. The 223 falls off pretty quick after 300. But really they are just for fun.
The 223 is just a practical and fun round. I use 3031 now but hade used H 335 and got great result too. The 45-70 is one I only use 3031 in as well as the 30-30. Just a great powder. So, yea good find for you. $25 is a windfall. lol
A pound of 3031 should load about 250 rounds of 223. Enjoy.