Lot-to-lot powder variation, how much of a difference does it make?

[Cassidy]

I was talking to a friend last night who is a long time 1000 yd shooter, and we were talking about lot-to-lot powder variation in group size for any given powder. Before this powder shortage, I have bought only small amounts (1-3 pounds) of various powders to find out which one my BR rifle likes the best, but taking this approach suppliers shipped different lots of the same powder even in the same order to the supplier. Using these different lots of the same powder, the best my BR rifle has done at 250 yds (after laddering and finding the optimal charge) is about 0.75"H x 1.75"W edge to edge (4 shots), which isn't so good, certainly not a bug-hole which is what I expected. Can the lot-to-lot variation in the powder, in this case N540, be causing this variance, given that this test was done in the early morning with 4-8 mph wind coming from 20 degrees over might right shoulder. How much effect can lot-to-lot variation have?

This also lead to discussion about why there is so much lot-to-lot variation for any given powder; it suggests that the in-process controls during powder manufacture are not so good in the industry. Do powder manufacturers have strict specifications for each type of powder, or do they simply test the muzzle velocity after production of a batch and assign that powder to the type of powder (RL15, H4350, etc) previously with that velocity (which I hope they do not do because it seems to me this latter approach is really sloppy).

Also, why, as far as I know, are there no powder manufacturers in the US that actually synthesize the powder before additives are added.

Lots of questions, all comments are welcome!

 

[stool]

canister powder....stuff sold over the counter is always given load data in gr..because the volume can vary. lot to lot is some number in the industry...probably less than 5%. some powder is common in the surplus world as just outside normal lot and sold on the open market. you can see this in 2230 where there is off lots with a letter in the end.

powder manufacturing is not an exact science...never has been.

imr8208 is a perfect example. they were given lots of oem milsurplus to copy. early lots were close, later were not and sucked in a 6ppc.
if you could figure how to make powder with a lot to lot of !%...you would be rich.

 

[wapiti25]

Each powder has it's own recipe. The chemistry is tricky so you end up with differences. When you buy powder in 1 lb cans that are different lots you could mix/blend say 3 lbs and end up with a powder that is the same for that batch you have. The blending should be done with powder of the same number/name and of about the same age, not bought 10 yrs apart.