Vihtavuouri powder - N140 vs. N540


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W.E.G.
December 7, 2010, 06:40 PM
My understanding is that N140 is "single-base," and N540 is "double-base."

I read somewhere that double-base powders are expected to be more "temperature stable" than single-base powders. That is, they are affected less by changes in temperatures.

I just ran some comparisons in Quickload.

Quickload tells me that N140 generally runs at a higher pressure, at any given temperature, than N540. That is an important thing to know, but it is not what I want to know about here.

By comparison when accounting for propellant temperature, the pressure increase from FORTY degrees to NINETY-FIVE degrees is:
4,280 PSI for N540
4,694 PSI for N140

So, the single-base powder, N140, fluctuates more in pressure by a "whopping" 414 PSI. Now mind you we are talking about 414 PSI in a cartridge wit a SAAMI spec of 62,336 PSI. That would mean that the 414 PSI in question accounts for just half of one-percent of the total pressure we are working with.

Maybe this is more of a RANT, than a question, but I just don't see the big deal in the idea that the double-base powder is APPRECIABLY a better choice than the single-base powder.

I welcome your thoughts and comments.

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mboylan
December 7, 2010, 07:46 PM
I would say that double based powders are not as consistent as single based powders. VV N140 is a proven 5.56 match winner with 75 and 77 grain bullets. VV N540 is not.

W.E.G.
December 7, 2010, 07:50 PM
Can you clarify your comment regarding "consistent?"

Consistent from one lot to another???

Consistent as to velocity for a particular powder charge?

Consistent as to metering in the powder measure?

NRA-Highmaster
December 7, 2010, 08:41 PM
I tried N540 with the 80SMK and I don`t see the big deal either. I don`t recall my 600 elevation being much different than an 80 loaded with N140. The N140 load was a good bit more accurate to boot.

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