IMR Enduron® 4955

Got good velocity and accuracy. Stopped 1 1/2 grains short of max for 300 win mag with 180 grain. Very satisfied

I just finished firing three loads in the 25 06 using a 117 gr. Hornady btsp. Starting with 51.5 grains of IMR 4955 then 52.5 and 53.5. Not max load but the faster I pushed it the more accurate it got! Also no signs of high pressure at all.

Like Alan I experienced failure on the case head right where the edge of the primer meets the edge of the primer pocket. .260 remington (custom with perfect headspace). Charge weight was 44 grains in Resized FGGM cases, primer was WIN LR and WIN LR Magnum. I got a blast of gas to the face and smoking around the bolt shroud on a remmy 700. 2 out of 5 cases had a pinhole in the mentioned location. Charge is 1.1 grains under max with a 142 SMK, and velocity averag was 2711 out of a 25 inch SS Krieger. For reference .260 FGGM factory ammo shoots the 142 SMK at 2742 average and has no issues.

IMR4955 is a great find. Not well known but I suspect more people will use it with more reporting. As stated by A. Williams, it can blow out primers at higher loads so build up carefully as always. Additionally, I use it in my .243 and pressures are not the same for all equal bullet weights. Ex: Nosler E-Tip 90's blew out the primers while Berger 90's shot fine: same 45 grains of 4955 out of Winchester brass. I'm getting 1/2 MOA with my 80 & 90 Berger's.

Getting .3 moa groups out of my 300 win mag with 168 grain barnes bullets@72 grains. Not sure on the range for safe loads anything over 72 and I start getting pressure signs. Like around 72.5 I see obvious primer flattening.

So far it is working as advertised. I worked up some 6.5x55mm loads. No signs of pressure, the velocity was what I was hoping for, accuracy is good. Very happy.

This is the first of the newer enduron powders I’ve worked with. I bought it because I couldn’t find the powder I prefer for 3006 rounds there are recipes listed for 3006 and am interested in the temperature insensitivity and anti fouling properties. It is a short fat cylindrical shape, rather than the long skinny cylindrical extruded powder I’m used to seeing. From what I can tell so far, you will end up with a full to compressed load. The powder compressed easier than the longer skinnier shaped powders. Metered uniformly, threw well and trickled well. I’ve a batch loaded up to test for velocity, accuracy, and pressure signs, but haven’t shot them yet. Which is the reason for 4 stars as I haven’t shot it yet, but if my loads come close to published results, I expect to be pleased.

Great powder as with all of the enduron line

This powder is Sierra's pick for accuracy under their 200 grain bullets. I have a very picky eater (Bergara B-14 HMR) and I've had very poor results with the factory ammo I've had to feed it just to get some brass on hand to load. Right out of the gate, this powder got me under ½ MOA and just over ¼ MOA on a 2nd try at the same load. I'm equally impressed and pleased with this powder.