Does anyone know the burning rate difference in the old Dupont 3031 and IMR 3031? I worked up loads to max with the DuPont using IMR data in .257 Roberts with no pressure signs of any kind. I think I have read that some of the old DuPont powders were slightly slower burning than IMR. Anyone have experience with the old Dupont in .257R? Thanks for any replies. Merg

Since the load data on the Roberts is only about in the 45K psi range, I really don't think you will find any problems popping up or any increase or decrease in real world performance between DuPont and IMR 3031.....

Good luck with it tho, and welcome to the forum!

cheeers
seafire

I ask this sincerely; Didn't Dupont introduce the IMR series of powders? Aren't they or at least weren't they one and the same? roger

This powder is quite old (probably bought in the 1960's and does not have the "IMR" brand on the can. The can is labeled DU PONT IMPROVED MILITARY RIFLE POWDER. NUMBER 3031. It was made in Wilmington, Delaware. My current can of IMR-4350 is made in Canada for IMR Powder Company. Du Pont did make IMR powders at one time but I don't know all the history of the company, just have read that burn rates have changed over the years. I found it unopened in a storage building a couple of years ago. It's clean looking and smells like new powder is supposed to smell. Merg

I bought a bunch of old DuPont IMR 4350 at an auction about five years ago (in the old cardboard cans with a small lid) It burns fine in -06, however I thought it was a tad hotter than the new stuff.
I have no chronographic proof of this, but the rifle kicks harder, muzzle blast is sharper, and it makes bigger holes in deer -all without pressure signs.
I am of the opinion that IMR powders have been the most consistent throughout the years.

quote:

Originally posted by merganser1:
Does anyone know the burning rate difference in the old Dupont 3031 and IMR 3031? I worked up loads to max with the DuPont using IMR data in .257 Roberts with no pressure signs of any kind. I think I have read that some of the old DuPont powders were slightly slower burning than IMR. Anyone have experience with the old Dupont in .257R? Thanks for any replies. Merg

I have used both of the 3031's in a .45/70 with the same (hot) loads, and see no practical differences.

quote:

DU PONT IMPROVED MILITARY RIFLE POWDER. NUMBER 3031.

Gosh! What do you suppose "IMR" means? IMPROVED MILITARY RIFLE POWDER, perhaps??

BUT, just as is wise when changing from one lot of the same powder type to a different lot, re-working the load is always advisable! You should do the same here.

It is my understanding that Du Pont used cotton linters to make the nitrocellulose used in making their powders. Later, after taking over and making powders under the IMR label, IMR began using sawdust as the source of nitrocellulose, which I understand made some difference in the burning rate, the IMR versions being a slight bit faster.
One example from personal experience is I once had a pet load for the 30-06 consisting of 49.0 gr. of Du Pont 4895 and the 150 gr. Sierra bullet. Accurate and killed deer just fine, althought a bit too destructive on eating meat. I switched to another load with a heavier bullet.
A few years back, I wondered just what kind of velocity that old load gave, so I bought a can of the now named IMR 4895 and laoded up a box with the same bullet, brass and primer as I used in that load probably 30 years ago. You can imagine my shock when I blew a primer. I went home and broke the ammo down and reweighed eack charge. They were dead on at 49.0 gr. Something was radically different here. Well, starting from scratch, 47.0 gr. proved to be the max load I could use with that powder, two full grains less that when Du Pont made it.
Now before some wag decides to tell me I should start from the ebginning, according to several of the newest loading manuals, 51.0 gr. is the max load. This leads me to a serious gripe I have with the writers of loading manuals, and I'm going to severely jump on Lyman in this instance. The latest Lyman manual (#48) says 46.0 gr. of IMR-4895 is the STARTING load and 51.5 gr. is the maximum load for a 150 gr. bullet in the 30-06 with the max load giving pressure data in C.U.P. readings. The Lyman #44 says starting is 46.0 gr., max 51.5 gr., Lyman #45 says the same, Lyman #47 says the same.
My point is, the Lyman #44 was copyright in 1967, the powder manufacturor has changed hands and at least one component in the powder and yet the same data is usable? I realize that retesting all those rounds from back in 1967 would be an expensive proposition, but wouldn't it be the responsible thing to do?
Most of the data in the latest Lyman manual is still in Copper Units of Pressure. (C.U.P.) and only the latest super wonder rounds and newset powders are done in pounds per square inch(P.S.I.). Just a something to think about.
I reserved the rest of that 4895 for shootin cast lead loads for which it worked just fine.
Paul B.