Powder lot change / velocity change IMR 4064

[markm]

Pappabear and I Shot some 178 ELDs out of his 16 inch LMT MWS today. I spun up 50 rounds of ammo in MEN brass with 2 different lots of 4064. Ammo was loaded on the Chargemaster on the same day, same everything... except for the powder lots.

We had the last half pound of an 8 lb jug that had a Vicks Vapor rub smell to it.... I mean STRONG. I'd loaded a bunch of 4064 before, but this 8 smelled odd. In any case.. the Vicks powder shot 98 fps FASTER than the newer lot of 4064.

We had seen a 60+/- change in velocity with Varget before... and I did a thread on that, but this was crazy. Almost 100 fps difference.

The hot stuff has a 2015 production code, and the milder powder is 2016 date coded.

[308sako]

I cannot offer knowledge, only opinion and observations of similar phenomenon. If one were to charge the cases by volume instead of weight I suspect the velocities might have been much closer. Did they bulk the same?

From what you have said the lots were not really that old compared to what many of us might find in our closets. I therefore assume you are referring to lot to lot variation only in your query.

Whether it is a drying or evaporation of a component of manufacture or a deterioration of the "active ingredients" it is just maddening... I guess one question that should be asked is; did your load with the original lot produce velocities that were in line with prior results, or had the powder become supercharged?

[masan]

I have 16lbs of 4895 that is so fast I cannot use it in a 6BRA (4895 being the go to powder for this cartridge). It was the newest (at the time) lot of 4895 available, and I had to wait it out until a newer lot came out that would actually work with the 6BRA.

I also have some (as in almost out) powder that was pulled from tracer rounds left over from Vietnam. This is the powder that dominated Short Range Benchrest competition to the point that 8208XBR was developed as a clone to it. To this day it still has the same burn rate, for everyone that still has any left (you see it getting shot at Nationals and other big events).

Both age and enviromental conditions can/do affect powder, as we all know. Sometimes I wonder if these wacky lots of powder come that way from the manufacturer or if something occured during shipping or at the vendor which cause the powder in question to behave so differently from what we expect.

[markm]

I don't suspect any temperature abuse or mis-handling. Just an impressive velocity swing. The older (menthal) powder actually popped a primer. That load was too hot. 42.3 gr yielded 2560+/- fps with a 178 out of a 16 inch gas gun. That's almost 20" bolt gun speed.

[308sako]

I think it would be quite interesting to see what the charge weights would differ if you have a measure that throws a relatively precise volume. Then with a charge weight of the hot lot you are comfortable with to see what matching volumes would do.

[masan]

I think it would be quite interesting to see what the charge weights would differ if you have a measure that throws a relatively precise volume. Then with a charge weight of the hot lot you are comfortable with to see what matching volumes would do.

If markm is also interested in this, I am willing to put my Culver styled measure from Bruno's up for the experiment. I don't use it to load for BR Competition anymore so I won't be in a bind without it for a few weeks.

It will accurately measure to 0.1gr by volume, so long as the user is consistent.