IMR 4320 - Varget replacement?

[<MADDOG>]

I just thought I would share some informal load testing with you gentlemen...

As we all know Varget has been a PITA to get ahold of. A month or two ago, IMR 4320 was available in 1-8LB quantities, and based on my google-fu, I ordered 8LBS based on some opinions of others that it was very similar to Varget. Below are my initial testing results: bash as you may...

Below is a pic of my latest testing today @ 100 yds during the beloved wind and at 65':

Left side: a ladder test of 77 SMK's. 7 shots total. 21.9gr to 23.1 at .2gr increments. No signs of over-pressure of any load. I did pulled the far right round.
Rifle: Savage 12FV(?) with 16x Millet

Right top: two different zero groups with 77 SMK's at 23.0 (I already tested that load over the past month)
Right bottom: British Radway SS109 tested for reference.
Rifle: Maddog AR15 built with 18" DTI barrel and ACOG TA11.

I did not chrono any loads due to my dumbarse failing to bring a good battery, but those will follow. As a note with the Savage; I was targeting a round I put in the paper with my Varget load (24gr @2950 FPS) with a 3 MOA adjustment down (you can't see it from from my shitty photography), and it was spot on. Which leads me to believe the velocities are close...

I also have promising results with .308 with 175 SMK's with my "Maddog built" LR308 during my initial ladder testing, but I did not take pics. Those results will also follow...

[B]Long story short: if you guys like Varget, you may wish to give IMR4320 a try!

http://i34.photobucket.com/albums/d108/pperron/PPTest_zps95eb5496.jpg (http://s34.photobucket.com/user/pperron/media/PPTest_zps95eb5496.jpg.html)

[Zombie Steve]

Yep. I've had some great results with 4320 in .308 and .223 (even a 150 grain .30-06 load, even though there was no load density). Darn near the same burn rate as Varget. Like most IMR powders, it's going to be temperature sensitive. Varget is almost totally insensitive to temp swings, so if that's what you're used to just be prepared. Mid range loads probably won't matter, but if you're going for top end, work up on a hot day.

All that said, if I saw an 8lb jug I wouldn't hesitate to use it. I think it's one of the more underrated powders out there.

[vossman]

Well that's good to know. Thx

[Alpha2]

Just checked my "cache la poudre", and I've got a lb jug of 4320, I'll have to make up some loads and check it out.

[duke_39a]

My 22-250 loves 4320. Great velocity and accurate. Works from 40 grains to 55 like a champ. Haven't used it in 308 or 223. Need to give it a try after seeing this.

[Zombie Steve]

Found an old picture of a work-up 7 shot group in .308 with 4320.

http://i183.photobucket.com/albums/x214/sbecht/DSCF1667.jpg

[<MADDOG>]

Steve,

Do you know the velocity per chance? I am at 2540 fps with a 175 SMK and 18" barrel at 43gr.

[Zombie Steve]

Unfortunately, those were the days before I had a chrono.

If you're getting good groups at 2,540 with a 175 I wouldn't change a thing.

[cysoto]

IMO, the biggest selling point in favor of Varget is that accuracy is not significantly affected by temperature swings. How temperature-sensitive is IMR 4320?

[bellavite1]

How would charges compare?
I don't suppose you switch them straight across (i.e. 42 gr of Varget to 42 gr of IMR4320)...

[Zombie Steve]

The data certainly isn't interchangeable, but they are such similar burn rates, they'll be close (43-44 grain area for .308). As to how temp sensitive, I can't quantify it... didn't have a chrono back then to tell you, but I know I shot that same load on a hot day (summer '08 - don't remember how hot) and I started getting pressure signs on the headstamp (vs 55 degrees when I shot that group).