Reloading take 2

[Koda]

Looking for a set FPS vs what length barrel and twist rate you have may not be the way to go with the powder and bullet weight you are choosing/having to use.

I have no idea what Im doing then. "load development" was something that tripped me up my first try, there are different ways Ive read about and many more opinions offered in forums etc. Im all ears for advice here, but otherwise Im working with what I've learned so far. I had last left off with a 1" group at 3051fps avg but that was just 4 rounds in a string. If I can achieve that with my new brass I'll be happy.

 

[gmerkt]

The -only- reason Im using IMR4831 is because its the only powder I could find and started with a few months ago but very limited supply from a private sale.

If I read your comments correctly, you started with some IMR4831 sourced from another shooter. Then you bought a new 8 pound supply of your own. It's possible there is enough difference from one batch to the other to cause you to review your original loads.

Re. Nosler brass. Some users have noted short case life due to enlarged primer pockets. More than usual compared to other brands. Some users have noted that Nosler brass tends to be softer and thicker. Thicker might lead to higher pressures given the same loading due to reduced capacity. Nosler acquired Silver State Armory in 2013, have made their own brass since then. Prior to 2013, Nosler bought at least some of their brass from Norma. Nosler doesn't date headstamp their product so it might be difficult to know age/source of the brass. But if it was purchased lately, it was made in the SSA facility.

Varget would be too fast for the heavies (120gr).

It wouldn't be first choice, but Hodgdon lists .25-06 loads for it.

H332 is supposed to have more bench rest records than any other powder.

A wonderful powder, one of my favorites for .223 Rem. but not appropriate for .25-06. Overbore cartridges tend to want slower powders.

H322 is very similar if not identical (at least in burn rate) to the milsurp IMR-8208. And now there is IMR-8208 XBR, but I do not know its record or burn rate.

I've read somewhere that contemporary IMR 8208 XBR came about as a failed batch of H-322. They both come out of the same plant in Australia, so I guess it could be true. Of course Hodgdon controls both brands. The shiny gold label and new name might be a marketing coup. And the basis for a slightly higher price. I've used both and haven't really noticed much if any performance difference. They are both great powders for their uses, small extruded kernel size meters like a ball powder.

 

[hawmanai]

I don't push the limits of pressure.

I get a load that works well then check to see if it shows pressure signs after laying in the sun on the dash.

 

[Koda]

If I read your comments correctly, you started with some IMR4831 sourced from another shooter. Then you bought a new 8 pound supply of your own. It's possible there is enough difference from one batch to the other to cause you to review your original loads.

Thats correct, originally I scored 2lbs and quickly burned up a pound when I decided to wait until I could get more powder to work with. Being new, I learned first thing that I was myself inconsistent in my processes to just quickly come up with a load recipe in under 2lbs of powder.
Im aware that there can be pressure differences between production lots of the same exact powder, I just dont know by how much... ? Will I need to start over or is it close enough to just check velocity and group size and adjust as needed?

 

[gmerkt]

I think I'd just make a small quantity of check rounds using data from your earlier efforts. See how that goes.

IMR 4831 has been made for a long time. Not only lot variations, but poss. also from age. Powder does dry out some over time, which affects weight. Which is a difference I've noted between powder lots. I've encountered a significant lot difference in weight on IMR 4064, which of course plays out in getting a consistant charge weight from lot to lot. Unless you're right on the edge of a maximum charge, this probably isn't a safety factor.

 

[Hemlock]

You've burned through 2 pounds of powder doing load development? That's about 260 rounds and you haven't found a satisfying load? Time to make some changes in your recipe. Bullet, powder, primer. Clean the barrel?

 

[Koda]

You've burned through 2 pounds of powder doing load development? That's about 260 rounds and you haven't found a satisfying load? Time to make some changes in your recipe. Bullet, powder, primer. Clean the barrel?

No, ive only used a pound and did change my brass and powder lot in the process.

 

[Hemlock]

I'd change the bullet. A 120gr bullet in a 25-06 is on the heavy side for that caliber.
Unless the gun has the proper rifling twist it may not stabilize that bullet.

 

[Koda]

I'd change the bullet. A 120gr bullet in a 25-06 is on the heavy side for that caliber.
Unless the gun has the proper rifling twist it may not stabilize that bullet.

whats a proper twist for a 120gr in this caliber?

 

[BigGame]

whats a proper twist for a 120gr in this caliber?

We often use weight as shorthand when talking about rifling twist, but in reality it's bullet length that has the greatest influence on stability (hence necessary twist rate). Take the stats for your bullet of choice and plug them into a twist calculator to learn the slowest twist rate needed to stabilize it. I prefer the JBM calculator, but there are several.

JBM - Calculations - Stability

www.jbmballistics.com

 

[Koda]

We often use weight as shorthand when talking about rifling twist, but in reality it's bullet length that has the greatest influence on stability (hence necessary twist rate). Take the stats for your bullet of choice and plug them into a twist calculator to learn the slowest twist rate needed to stabilize it. I prefer the JBM calculator, but there are several.

JBM - Calculations - Stability

www.jbmballistics.com

that calculator doesn't output ideal twist rate but it outputs "stability "...

Nosler doesn't recommend a twist rate for the 120gr partitions but from what Ive read elsewhere 1:10 is fine up to 120gr and Im not keyholing even out to 300yds with these and Im approaching 1" groups at 100yds so... ?

Edit: I knew I looked into this when I chose this bullet, Noslers reloading data suggests a 1:10 twist, which is what I have.

How does a "stability" of 1.431 look?

 

[BigGame]

How does a "stability" of 1.431 look?

That should be fine, particularly since it's at sea level. The stability will be stronger at higher elevations.

A stability factor of 1.4-1.5 is generally considered fully stabilized for most common applications.