2400 comes to mind as a powder with lower loading data today!

So, the powder you bought 31 (almost 32) years ago is different than the powder you just purchased.

Name just one thing that has not changed in the past 31 years.

I wouldn't say that H-335 has bee "reformulated", since powders (all powders) vary from lot to lot. That is why it is suggested that when you change ANY component you re-work your load. And I just have to wonder how many different lots of H-335 have been packaged since 1973.

What I have found in my testing is:
H-335 From 38.0 grains to 47.0 grains
Remington 9-1/2 Primer

Without addressing the particulars of H335, what you have experienced seems to be common with the pasage of time. Many of the older load data tabulations are distinctly unsafe with newer lots of (fill in the blank) due to more quickness. Don't know why it has to be this way, but it is.

I think ball powders are finickier than stick powders, so who knows what 31 years does.

H335 and a .223 go together like bread and butter.

Back as a young-un, I stumbled into a great sale on H335. The price of $1.65 a pound comes to mind. Anywho, I stocked up. This was like 1973. Used my 45th edition Lyman load book and found that the full load of 50.5gr worked good in my Savage .308 with 150gr Speer hotcores.

Fast forward to early this year. I use up the last of the powder. Get a fresh can. When I start using the new powder...Boy Howdy!....I got pressure galore in the 308!

Look at my more modern load books and I'm seeing max loads for that .308 of 44 or 45 grains. And with this new "H335"...I believe em! Even a 45 gr load will give me sticky extraction occasionally.

It occurs to me that they may have reformulated H335 a Looonnngg time ago, and it is only now catching up with me. Maybe the big sale I ran into was because a supplier was dumping his load of "old H335".

Does anyone know exactly when this change took place?

I used to love my old stuff for 223 and 308. This new stuff works just fine in the .223. But the .308 accuracy is gone and I'm not sure I trust it in that caliber anymore, pressure wise. This is a completely different powder.

There have been changes in the way powder is made. When Du Pont sold their powder factory to IMR, and when hercules sold out to Alliant, both outfits changed from cotton linters to make the nitrocellulose to literally, sawdust. The change make the powder less expensive to make, but also makes it faster burning.
My pet load for the 30-06 with IMR-4895 had to be reduced by two full grains, and my .357 load with #2400 (Hercules) by 1.5 grains. Elmer's old 22.0 gr. of 2400 for the .44 mag. had to drop by two full grains.
Strange, but now that the powder is cheaper to make, the price went up, rather than either hold steady or decrease.
Paul B.