IMR (Improved Military Rifle) smokeless powder intended for reloading of sporting rifle ammunition. Military ammunition is also loaded with IMR powders, but generally the surplus military powders do NOT correspond directly with those available from IMR canister powders. The number is one originally assigned by the manufacturer (DuPont) to the powder with a specific burning rate/chamber pressure/ under bomb calorimeter test conditions.
They are single-base nitrocelluose smokeless propellents distinguished by granule size, perforation size, and deterrent coating.
I believe the IMR series is identified by burning rate, with the lower numbers (IMR 3031, 4064, 4895, 4350, 4831, etc) designating fastest to slowest burning rate under a specified set of conditions.
Adjacent number IMR powders can actually switch places under different load conditions in the same cartridge caliber.
That is, burning rates are not absolutes, but are variables.
The number assigned to a powder (IMR-4350, IMR-4831, IMR-4064, RL-10, etc.) means absolutely nothing. It is the number the manufacturer assigend to that powder.
Way back when, the Governement assigned IMR-4350 a rating of 1.0, which pertained to it's burning rate. All powders are referenced to IMR-4350 when calculating burning rates.
If Accurate and IMR and Hodgdon have a powder called "4350" it does not mean they are the same. They are extremely similar, but not the same.
Likewise there are powders on the market (namely Hodgdon) which have one name when purchased in a Hodgdon container, and the exact same powder, when purchased in a Winchester container or an Australian container, have totally different names.
The old Hurcules powders had names like Red Dot, Green Dot, Blue Dot because that is how the manufacturer differentiated between them, by adding colored flakes to the mix.
Other manufacturers have gone the opposite direction, take the "Clays" powders for example...there are 4 different powders from Hodgdon that have the name "Clays" or "International" in them....tell me that doesn't cause confusion!
There is no convention in naming powders...it iw whatever the manufacturer feels like naming it when it is shipped.
I've used it in the same applications one would use the IMR product, with satisfactory results. Some fiddling up or down is necessary, but loads are usually close to what's normal with Dupont's (and probably Hodgdon's) 4350.
I bought a couple pounds because it was cheap and it worked just fine.
IMR-4350 and AA-4350 are very close in burning rates and yes AA 4350 is also a stick powder. I have used both in my 309JDJ with great results. JD's load sheet for the 309JDJ lists 2.0 grs less of AA4350 for a max load when compared to IMR4350.
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