Very slow 8lb jug of H4831. What should I do?

[Texas10]

Maybe this is a dumb question, but did you pull down several of the sellers hand loads and see what the powder charge weighs on YOUR scale? His and your scale may not be in near agreement.

I would be surprised if powder lots alone would explain the velocity difference, but that combined with scale errors just might.

 

[DCRYDER]

I threw weights with my new Lyman Gen6, checked with 2 other digital scales, one goes to 0.xx

 

[DCRYDER]

I did not pull his bullets and weigh his charges.

 

[Longrange57]

Been there and done that as well but did not see extremes you are seeing. Only used H4831 in one rifle and it shot 25 slower than H4831sc. Having more surface area with shorter kernel slightly speeds up velocity according to conversations I had with Hodgdon years ago. As a side note as has been noted above, last year I had a scale from My Weigh that went bad. Replaced with a different scale and calibrated properly, my loads were shooting approx 15-20 fps slower with everything identical. I simply loaded up accordingly and everything is fine. Could be a combination of things. Just my 2 cents.....go to 4831sc....you will be much happier!

 

[Hohn]

It is chemically the same, but the formulation is different. Not trying to be obtuse, the term "formulation" has a pretty wide range of definitions and we are apparently not using the same one. As noted by Fred B., the smaller kernels of H4831sc provide significantly more surface area and could enhance the combustion rate, even though the two powders are chemically the same. Alternatively, I have also seen upwards of 75 fps differences between Lots of H4XXX powder as XTR mentioned, so it might just be Lot-to-Lot variance. In that event, increasing the charge weight might solve the low velocity problem, but only if you have sufficient case volume. I'd be cautious testing that theory at the very high end and test in small increments due to potential over-pressure issues. Let us know what you figure out. Good luck with it.

At the risk of being even more pedantic-

Having the same chemical formulation doesn't mean that the distribution of that chemistry will be uniform. Many powders have coatings and such to improve temperature stability or resist coppering, etc. These are often not part of the initial formulation, but are applied *after* the powder is cut, similar to the way powder is graphited.

Adding the variation in chemical distribution on top of the geometric variation in the kernels-- and then the different lots and barrels, and it's not at all surprising to see 4831 in your gun perform differently than 4831sc in someone elses gun.

If they were essentially interchangeable, why would they go through the hassle of repackaging, renaming, and generating distinct load data?

 

[rsmithsr50]

WELL if you insist on listening to the sc shooters, just ship the rest of the 8lb'er off to me.
i'll shoot it.

 

[338 dude]

Those 1/2" groups were 3 shot groups.

I've shot a lot of short range benchrest over the last 12 years, so most of my experience is with fast burning powders, never saw this much variance with n133, H322, H4198, or Rl7.

At 58.5 gr H4831 @ 2818 fps there was NO bolt click, no swipe mark, rounded primers (CCI200) and zero cratering. With his loads of 56.9gr H4831sc at 2850-2875 same thing.

I may play with that powder a little more. Got a few pounds of H1000 and Rl23 to tinker with too.

I have a couple buddies with 28 Noslers to whoop up on at the informal 1,000 yd gong matches, just trying to squeak out all the edge I can.

Thanks all

RL23!!!

 

[Fred B.]

At the risk of stating the obvious, these are the factors in this case that might be affecting MV:

• Powder size/lot difference
• Previous owners scale may not have been accurate
• Seating depth and case headspace (affects case volume)
• Neck tension (affects powder burn rate)
• Primer brand/type (magnum vs standard)
• .....

Even if you find and prove exactly what happens and why, it will not make a difference.
At the end of the day, you have to find what works best with what you use and how you load.

 

[STOMP442]

Get some H4831sc and call it done. Save the other stuff for foulers or some other caliber.