Midway has 5LB'ers in stock.

I guess/hope it is starting to be more available now; I was at a gun show last weekend and there was about 50 one pounders of just RL15 there with 3 vendors.

I think I have a couple of these new 5lb jugs,loaded up the 470 to test at the range last october,I was getting ready for a late season African hunt,much to my surprise my Heym was printing six inches @50 yrds,the temps were in the low 40's,I could not be sure if it was powder variation or temp causing this,I left that gun at home.
This summer I took it back out to test my loads,the temperatures being much hotter,mid 80's,I finally got the gun to shoot like it used to,an inch @50,I had to increase my load by three grains of powder shooting Woodleigh softs & 7 grs shooting NF solids,you can bet I was watching the chrono pretty carefully,did'nt want to stress my rifle,just thought nI would share my experience with R15,I had heard of slower & faster batches of powder,but this was the first time it actually happened to me.

You might do a search on AR and the Web for temp sensitivity of RL-15....there are/is/was several good tests done and published(somewhere?) on velo variations with RL-15 going from low temps to high temps...basically RL-15's velos could range over ~100fs or higher from lo to hi temps...

Hodgdon's Extreme powders were relatively insensitive to temp changes but you still need to check your load velo's and groups at the temps for your hunting times/locations.

I did some hot/cold cooler tests with 375 H&H, 416 Taylor and 7-08 (for rifle and pistol) with RL-15 I was using in all three for the most accurate loads in those calibers, that gave me wide eyes...and some impromptu 223 loads that got hot on the dashboard in summer heat.

There was a very noticeable difference in the "pop" between the hot ammo and the same ammo when it cooled off and the velos were different than when I developed the loads, most during May-July and temps between mid 60's to low to mid 80's.

After than I pulled about almost 300 22 cal bullets from boxes that got real hot, dumped the powder and reloaded with Varget.

Hot, hotter and hottest was a real problem when I lived around the Las Vegas area...EVERYTHING in coolers or under AC that was lucky to get down to the mid 80's even at night.