I been using IMR 4955 for a while now. I keep buying it because even though it's discontinued, Dave Sheer still has stock, the price is at R700, and I figured out how to use it in the calibers I shoot.
I have found that the burn rate is higher than what the manufacturer says it should be, by such a high margin that it may in some cases be unsafe to use the IMR load data.
The indicated equivalency to H4831 is very wrong.
I find that the burn rate is higher than N204, where Hodgdon says it's below N560.
I'm amazed that such an established manufacturer from the most litigious country on the planet would get something that wrong.
Something wasn't lekker there, they even discontinued that product line.
I understand that powder burn rates are relative for a particular case capacity, usually .308 size.
I also know that the burn rate can change with the volume of powder.
But this 4955 was not kosher to start - even in my .243 it burns more like a slightly slower Varget.
Remember that one batch of S365 ?
Does this container have a burn rate on it or a deviance indication?
I did a QL calc for a 243 with a 87gr Vmax. Propellant was IMR4451. I had to reduce the burn rate from .575 down to .528 to get the numbers to agree. Rather significant change - possible long freebore?
Quote from: Treeman on Jan 06, 2024, 04:28 PMRemember that one batch of S365 ?
Does this container have a burn rate on it or a deviance indication?
I think this is just a case of mis-labelled product. The discrepency is very consistent over all the years the powder was produced.
I've read on a few forums people trying the powder using the provided equivalency, and blowing primers on the start load, in various calibers.
I found the opposite with IMR4350. It needed a grain more to get the predicted velocity on QL.
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.
100% consistency isn't a story I'd buy readily about any propellant.
Quote from: oafpatroll on Feb 13, 2024, 09:30 AM100% consistency isn't a story I'd buy readily about any propellant.
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I think much larger batches lead to greater consistency. Making a 100 bottles 10 times to a consistency is far harder than making 1000 bottles that are all the same one time.
Quote from: Treeman on Feb 13, 2024, 10:51 AMQuote from: oafpatroll on Feb 13, 2024, 09:30 AM100% consistency isn't a story I'd buy readily about any propellant.
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I think much larger batches lead to greater consistency. Making a 100 bottles 10 times to a consistency is far harder than making 1000 bottles that are all the same one time.
If a propellant manufacturer failed to achieve consistency tin to tin from the same batch I wouldn't think they were worthy of having a license to produce the stuff. Perfect consistency (i.e. 0% deviation) across batches however sounds like a theoretical possibility rather than a realistic target unless the budget to achieve that was vast.
Wow.
Quote from: Againstthegrains on Feb 13, 2024, 09:12 AMI found the opposite with IMR4350. It needed a grain more to get the predicted velocity on QL.
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.
No. Blame the shooters that demanded foreign powder. They got all hyped up about forum posts where American reloaders talk about how consistent powders X is and how they haven't changed their load in decades and still shoots "1/2 MOA all day long" "when they do their part". Further reading would have shown that said marksman doesn't even have a chrony, but people lose their critical thinking skills on the internet.
I remember those threads where people swore high and low that it makes more economic sense to buy powder at 3 times the Somchem price because "you only have to do load development once". Having been forced to use Varget and N140 I can say that they must have been smoking something. And by above posts seems like other expensive powders suffer the same problems.
Quote from: Againstthegrains on Feb 13, 2024, 09:12 AMI 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.
The obviously sensible thing to avoid is a manufacturer that repeatedly blows up their own factory.
There is no such thing as 100% consistency across batches by any manufacturer, as stated by
@oafpatroll.
However, you can be certain that your regular load is not suddenly going to bind the bolt in the next batch number.
Or that the powder in the tin is not incorrectly labelled.
I won't use Somchem powder even if you give it to me for free, except as plant fertilizer.
Quote from: janfred on Feb 13, 2024, 12:07 PMI remember those threads where people swore high and low that it makes more economic sense to buy powder at 3 times the Somchem price because "you only have to do load development once". Having been forced to use Varget and N140 I can say that they must have been smoking something. And by above posts seems like other expensive powders suffer the same problems.
If you found that you needed to redo load development with Varget and N140, it would have been worth knowing the batch numbers.
I'd be interested to know what you observed, or what was the measured criteria in your case that made you decide it was due to powder inconsistency.
I've used multiple tins of Vihtavuori and IMR in three target rifles, and I've not yet had to backtrack to find out why the load changed. I stopped recording batch numbers years ago, so I don't have record of if the batch numbers have changed across the tins.
I came to rifle reloading relatively recently so have never used somchem powder for that application as it its availability was already iffy. My main rifle powders have been IMR 4350 and 4198 and they have given me consistency across 15+ bottles of each such that velocity differences with the same loads have fallen with shot to shot variation.
I have used somchem powder in pistols and shotguns for > 25 years of which 10 or so was as an enthusiastic amateur competitor who trained a great deal and sometimes shot 500 handgun rounds a week. Been through countless tins of MS, MP and more recently 121 without any issues of any sort. The stuff may not be the gold standard but it's also not kryptonite across the board.
Quote from: Againstthegrains on Feb 13, 2024, 09:12 AMI found the opposite with IMR4350. It needed a grain more to get the predicted velocity on QL.
From 243 upwards a normal load is 40gr or more. One grain then relates to a 2,5% decrease in volatility, which is way below the 10% norm that is normally mentioned. A QL prediction is just that, although I find that the foreign propellants give fairly accurate predictions if you give measured data for your firearm.
Quote from: Againstthegrains on Feb 13, 2024, 09:12 AMI 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!
Quote from: BBCT on Feb 13, 2024, 10:03 PMQuote from: Againstthegrains on Feb 13, 2024, 09:12 AMI 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.
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.
Quote from: big5ifty on Feb 14, 2024, 06:42 PMI 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.
Quote from: oafpatroll on Feb 14, 2024, 06:46 PMQuote from: big5ifty on Feb 14, 2024, 06:42 PMI 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.
Quote from: janfred on Feb 15, 2024, 05:39 AMSo, 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.
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.