IMR 4955 - odd burn rate

[BBCT]

I do believe that the story that imported powders are 100% consistent between batches was hyped up and sold to us by importers (who had never used the stuff before) when there was no Somchem to go around.

I've been saying this since imported powders first became available and 100% of the time I've been ridiculed and abused. Never ever has anybody agreed with me or held the same opinion until now. I can't tell you how satisfying it is to see that other people have caught on!

[oafpatroll]

I do believe that the story that imported powders are 100% consistent between batches was hyped up and sold to us by importers (who had never used the stuff before) when there was no Somchem to go around.

I've been saying this since imported powders first became available and 100% of the time I've been ridiculed and abused. Never ever has anybody agreed with me or held the same opinion until now. I can't tell you how satisfying it is to see that other people have caught on!

People choose to believe magical bullshit about all sorts of things. I've noticed a strong correlation between how much they spend and how hard they believe the bullshit. I have for example challenged a couple of my spendy mates to prove that their multi thousand rand per litre cleaning and lubricating potions work better than eds red for cleaning, atf & paraffin for oiling and lanolin for greasing and that my guns are worse off for me abusing them so. Haven't had any takers so far but they 'know' that their stuff is somehow way better.

I don't struggle with the idea that propellants come in more and less consistent flavours but there are a great many factors at play other than them not being from Somchem.

[big5ifty]

When it comes to powder, the powder manufacturer quality control matters when you want long range precision and load consistency across batch numbers.

For pistols and revolvers, a velocity difference of even ten percent across batch numbers does not affect your competition score enough to worry about. And if it did, you can reload three rounds and re-test velocity and you're done.

For hunting loads, for hunting shot distances, even five percent may make a bit more of a difference, but not enough that you will completely miss your target.

I need to shoot within two MOA at one mile.

If the powder is two percent different across batch numbers, I need load re-development. That is not just adjusting powder and shooting a couple of rounds over a chrony.

That means the cost of bullets, primers, powder, range fees, fuel and the wasted time of the extra days necessary to do the reloading and shooting.

[oafpatroll]

I need to shoot within two MOA at one mile.

If the powder is two percent different across batch numbers, I need load re-development. That is not just adjusting powder and shooting a couple of rounds over a chrony.

I'd guess that puts you right at the pointy end of the pyramid of consumer profiles so i can understand why you'd want that level of consistency and be prepared to pay for it. 

[janfred]

I need to shoot within two MOA at one mile.

If the powder is two percent different across batch numbers, I need load re-development. That is not just adjusting powder and shooting a couple of rounds over a chrony.

I'd guess that puts you right at the pointy end of the pyramid of consumer profiles so i can understand why you'd want that level of consistency and be prepared to pay for it. 

So, of the powders you used, which give you the load consistency over different batches? I do know it is not Varget or N140.

[big5ifty]

So, of the powders you used, which give you the load consistency over different batches? I do know it is not Varget or N140.

As I said, I stopped recording batch numbers a few years ago. There is no way to now confirm if the powders I used had batch numbers that were different over time.

I regularly used IMR 4451, IMR 7977, and still use N555 and N570. I can go back to any load recorded in my book with those powders and duplicate it, without concern for the batch number.

The only issue I did find was the actual burn rate and energy of the IMR powders was higher than indicated by the manufacturer, in my calibers. That does not affect the consistency.

I'm moving to the Vita powders exclusively now, since the IMR range is discontinued, and I've used up all my IMR, except for 8133 which I only tested once, and found is almost identical by weight to N570 in the +-100 grain charge weight.

[janfred]

Well, the batch of N140 that came in at the beginning of 2023 is significantly slower than the batch before an the ccurrent batch.

As for Varget. The differences between batches is not that much, but would not make it suitable for your ELR shooting accros batches.

I have learnt to do at least some load development regardless of powder. And yes, sample size is small, but enough to prove that imported powders are not the constant that it is advertised as.

As an ELR shooter I am surpised you do not. But then again, 2 MOA is quite large.