[JTofGPD]

I bought a keg of h4350 (upc# 3928850092). Next to the h4350 it says "hodgdon EXTREME powders. Hodgdon online notes max of 59.0 gr with H4350 in 30-06 using a 165 gr sierra HPBT. Sierra manual notes a max of 54.5 H4350 if i recall correctly for the same pill (i use the manual from the local sports shop thus dont have it with me).

The keg label data matches the info on hodgdons site. Just the difference between Sierra and Hodgdon worried me. Any input would be helpful... I will likely put off loading tonight and call Sierra and Hodgdon tomorrow or monday if I don't get it sorted out..

Thanks!

 

[JLA]

Sierra used a different set of components to develop thier load. thus they got different pressure readings and thier data came out different. This is why it is safe practice to startt low and work up regardless of the data you use. But It is best to always try to match the components you load as closely as possible to the data you select.

H4350 is H4350, it has been an extreme powder for as long as I can remember

 

[BobMcG]

Personally, I'd begin with the Sierra starting load and work up.

The Sierra manual max is actually @ 54.1gr of H4350; they were using Federal cases and Fed 210 primers for 2,880fps out of a 26" Savage barrel.
I don't know what Hodgdon used for cases and primers or what kind/length barrel they used to get 2,938fps. Maybe they'll tell you.
It's a little interesting to note that for the Sierra bullet they expressed pressure in the older CUP and the Hornady bullet in PSI. Sierra doesn't state pressures.

There's also a similar difference when comparing the same Sierra bullet but using IMR-4350. Sierra's max is 56.0gr while Hodgdon's is a compressed load of 60.0gr.

 

[BobMcG]

H4350 is H4350, it has been an extreme powder for as long as I can remember

It's probably been an Extreme powder for some time now but I do have a partial pound of H4350 pre-Extreme powder left from years gone by. I would imagine it was reformulated to make it less temperature sensitive.

 

[Bindernut]

Yup, H4350 is H4350. Nothing changed with the performance when they added the Extreme to the label quite a few years ago. I'd suspect the formulation didn't change either.
Hodgdon's "Extreme" line of powders is their extruded stick powders. Their ball powders are the "Spherical" powder line.

I've got a few bottles with the older label as well.

 

[LDBennett]

There are a lot of things that effect pressure besides the amount of powder:

The case volume (as derived from the case wall thickness... military cases often have less volume than commercial cases and the wall thickness may vary between commercial cases as well)

The friction of the bullet against the bore of the barrel (pure cooper bullets often require different powder levels for the same exact same bullet weight, for example)

The power of the primer (and primers vary from manufacturer to manufacturer, even within the same nominal size).

The free bore of the rifle's chamber

How close you seat the bullets to the start of the rifling when chambered

ETC.

Any loads where the stated pressure levels are measured in CUP may differ significantly from loads whose pressure levels is stated in PSI. The earlier CUP system only record the effect of all of the pressure over time whereas the PSI system allow the tester to see the pressure as a curve over time. The later system gives the tester a much better insight as to what is really happening inside the case during firing and its test results probably are a better indication of reality. Many recent reloading manuals have had the loads adjusted after re-testing with the later equipment.

But in general I have found in the past that Hodgdon data typically uses larger powder loads than Sierra (???). It may be the difference in the testing equipment used to get the pressure data, both the transducers and the pressure barrels (??).

I start close to the staring load and work the load up while checking for accuracy. I often stop long before the listed max load and NEVER exceed the listed max load in the manual that has the hottest load. I have a dozen or so old and new manuals and research the data before I start reloading. But I defer to the latest manuals where there is a difference.

LDBennett

 

[243winxb]

Different component = Different pressure.

 

[oneoldsap]

My first choice of reloading data is the manufacturer of the bullet being used . My second choice is the powder manufacturers data . If I have neither I will cross reference the powder in 3 manuals and average a starting load , and work up from there . Never reload anything with out cross referencing at least 2 manuals , this avoids using bogus info , due to a misprint in one manual . It's standard operational procedure among most smart reloaders !

 

[JLA]

And very good advice to boot. Buy some manuals.. I think ive got 7 or so..

 

[JTofGPD]

Thanks for the advice all. I will check with sierra and hodgdon tomorrow then check my hornady #2 and new speer manual. I am comparing amount of powder used with same bullet weight, correct? Even though they are different bullets?

 

[JLA]

correct. That will give you the ballpark you can safely work in. I personally use the highest start charge with the lowest MAX charge when crossing data to develop a load. then IF and ONLY if I apporach MAX without over pressure signs, ill go ahead and load over max so long as the results continue to improve and pressure signs stay normal.

 

[243winxb]

Not all Bullets are Created equal

Bullets & Pressure - A long bearing surface will make more pressure than a shorter one, when its comes in contact with the rifling. The lead alloy used for the bullet core can be hard or soft, harder making more pressure. Sierra uses 4 different alloys. A thicker jacket if used will produce more pressure. Solid base or copper bullets will be different than lead core types. So, use a starting load of powder & work up.

 

[JTofGPD]

I called both hodgdon and sierra. Both acknowledged the difference in their data is pressure barrels(Hodgdon) and actual firearm barrels (sierra). Both advised to start closer to 49 grains and work up to a max. I will keep you all posted!

 

[BobMcG]

A small but interesting excerpt from an ExteriorBallistics.com (Sierra) powder burning rates chart. Are the two powders in blue highlight 100% the same "exact" powder formula?
......................
Hercules/Alliant Reloder 15
Hodgdon H380
Winchester 760
Hodgdon H414
Vihtavuori N150
Vihtavuori N550
Accurate Arms XMR-4350
IMR 4350
Hodgdon H4350
Hodgdon H4350 Extreme
Norma 204
Hercules/Alliant Reloder 19
Vihtavuori N160
Vihtavuori N560
IMR 4831
Accurate Arms XMR-3100
Winchester Magnum Rifle
......................