.260Rem, 140 A-Max, IMR-4350 max?

[FiveInADime]

There's not a load in the Hornady manual for this. Hogdon's data indicates a 43-grain max for a 140 Nosler Partition but that's a drastically different bullet shape. Hogdon doesn't list a starting load either.

[Jim Watson]

In the absence of a "recipe" I would recall the rule of thumb that a starting load is 10% less than a maximum load and go from there.
That ought to take care of the difference in bullets.

[A_Gamehog]

The Accubond and Balistic Tip are very similar.

http://www.nosler.com/260-remington

[Clark]

I have seen some trends in gun forums over the years.
20 years ago in 1994 before the world wide web had gun forums, we had usenet rec.gun and the most popular issues were:
1) Can I shoot 38 special in my 357 mag?
2) What gun to buy for my girl friend with small hands?

Now in 2014 with hundreds of gun forums, we have new trends:
1) Shortages?
2) 260, 140 gr 4350 what load?

I am trying to keep up with the times.
My first 260 I built in 2009 is 10" twist without a prayer of shooting 140 gr.
The second 260 I built was in 2011 with 9" twist and no hope either.
I have a third 6.5mm barrel now on order [16 to 18 weeks] with 8 inch twist [should stabilize 140 gr], but I now have a 6.5-06 reamer, so that barrel may not turn into a 260.
I may have to order a 4th barrel so I can participate.

[FiveInADime]

Originally Posted by Clark

I have seen some trends in gun forums over the years.
20 years ago in 1994 before the world wide web had gun forums, we had usenet rec.gun and the most popular issues were:
1) Can I shoot 38 special in my 357 mag?
2) What gun to buy for my girl friend with small hands?

Now in 2014 with hundreds of gun forums, we have new trends:
1) Shortages?
2) 260, 140 gr 4350 what load?

I am trying to keep up with the times.
My first 260 I built in 2009 is 10" twist without a prayer of shooting 140 gr.
The second 260 I built was in 2011 with 9" twist and no hope either.
I have a third 6.5mm barrel now on order [16 to 18 weeks] with 8 inch twist [should stabilize 140 gr], but I now have a 6.5-06 reamer, so that barrel may not turn into a 260.
I may have to order a 4th barrel so I can participate.

I know this is old but I wasn't looking for "what load" I was looking for a working MAX with IMR4350. I have a 26" Shilen 1:8" twist. So thanks for the musings.

[Clark]

If I type "260 140 gr H4350" into google, the first page is 10 hit from 10 gun forums, not this one.

https://www.google.com/search?q=260+...m=122&ie=UTF-8

1) 44 gr
2) 44.5 gr
3) 41 gr
4) 42.5 gr
5) 40.5 gr
6) 43 gr
7) 46.2 gr
8) 45 gr
9) 41.5 gr [I am not a member at this forum]
10) 43.1 gr

[FiveInADime]

Originally Posted by Clark

If I type "260 140 gr H4350" into google, the first page is 10 hit from 10 gun forums, not this one.

https://www.google.com/search?q=260+...m=122&ie=UTF-8

1) 44 gr
2) 44.5 gr
3) 41 gr
4) 42.5 gr
5) 40.5 gr
6) 43 gr
7) 46.2 gr
8) 45 gr
9) 41.5 gr [I am not a member at this forum]
10) 43.1 gr

Well that would be great if I were looking for loads for H4350 and not IMR-4350. In my experience the two powders behave very differently.

[Jimro]

FiveInaDime,

What I do in situations like this is use a linear approximation using the most comparable bullet I can get good data for. The Sierra 142 SMK is a pretty good proxy in my opinion.

Sierra lists 40.2 grains as max charge with a 142 SMK for a velocity of 2600 fps. Starting charge of 35.9.

Now I take the max charges with listed velocity, to get a fps/gr number.

Sierra has pretty conservative data, but it looks like 64.67 fps/gr of powder for Sierras data, and 63.14 fps/gr for Hodgdon's data. If you want to extrapolate a 2700 fps max charge from the Sierra data because you aren't using a Sierra bullet (above their published max load) it would be 42.7 grains of IMR 4350.

Now to check pressure, since Sierra doesn't list theirs, we'll use Hodgdon's data gives us 1325 psi/gr and this puts the estimated pressure at 56,602 psi. 10% reduction starting load is 38.4 gr.

I don't know if this is any help to you at all, someone with Quickload might be able to give you a warmer fuzzier feeling.

Hope this helps.

Jimro

[reynolds357]

Five in Dime, you can use Imr powder with Hogdon data on the 4350 powder. H4350 builds slightly higher pressure than IMR4350.

Anyway, the Amax has less bearing surface than the partition so figuring that one out wont be too hard unless you plan on deep seating the A-max.

[FiveInADime]

Originally Posted by Jimro

FiveInaDime,

What I do in situations like this is use a linear approximation using the most comparable bullet I can get good data for. The Sierra 142 SMK is a pretty good proxy in my opinion.

Sierra lists 40.2 grains as max charge with a 142 SMK for a velocity of 2600 fps. Starting charge of 35.9.

Now I take the max charges with listed velocity, to get a fps/gr number.

Sierra has pretty conservative data, but it looks like 64.67 fps/gr of powder for Sierras data, and 63.14 fps/gr for Hodgdon's data. If you want to extrapolate a 2700 fps max charge from the Sierra data because you aren't using a Sierra bullet (above their published max load) it would be 42.7 grains of IMR 4350.

Now to check pressure, since Sierra doesn't list theirs, we'll use Hodgdon's data gives us 1325 psi/gr and this puts the estimated pressure at 56,602 psi. 10% reduction starting load is 38.4 gr.

I don't know if this is any help to you at all, someone with Quickload might be able to give you a warmer fuzzier feeling.

Hope this helps.

Jimro

That's exactly what I was looking for, and your numbers make real good sense. Thank you.