Best available powder for 6.5 Creedmoor

[Meateater69]

OK I'll put my hand up to a point I have been challenged on. According to GRT (although not tested), RS60 should give pretty much the same result (within 10fps) as RS70, albeit with less fill, in my setup. Indeed, if considering temp sensitivity, RS60 also wins on that score too.

Rheinmetall

www.reload-swiss.com

On that basis, I retract my claim that no other powder comes close

 

[Roonster]

Hornady stated that 6.5mm Creedmoor was designed from the ground up to specifically use H4350. But then the EU banned that powder.

In my testing I personally haven't found anything that works nearly as well as H4350 in 6.5mm Creedmoor.

In testing EU alternatives I found:

N150 worked OK, but was a little too fast (pressure before desired velocity was achieved).

N160 worked OK, but was a little too slow (case fill before desired velocity was achieved).

Back in the day I reckoned a N155 would have been ideal, but then they announced N555 instead – which in theory should be ideal – but you'll lose about 1/3rd of your potential barrel life what with it being a double-base powder). Not really a deal-breaker for stalkers perhaps, but it's definitely a consideration for target/string shooters.

RS62 works really well, in terms of wide, predictable nodes - but it doesn't produce the same MVs as some of the other powders. Not an issue if you value consistency/predictability over rushing to failure at the fastest possible MV speed. I've yet to attend a competition where they ignored shot palcement and handed out silverware for the person who logged the fastest MV on their chrono.

RS60 also works really well, but the same comments about double-base & reduced barrel life.

RL26 is THE new magic powder, but it's almost as hard to find as H4350.

I also tried RS70, but it went WAY over pressure on my first (lowest charge weight) test cartridge. So I got a bit scared of it. This is the main problem I have with RS powders - a lack of reliable load data. You really do have to cross your fingers when you are load developing with RS powders.

A wee word about Vhitavuori 'High Energy' (N5xx double base powders). In my testing I found that the single base N1xx powders were actually higher energy than the N5xx powders – but the N5xx powders were significantly higher density so you can pack way more N5xx powder into a case (by weight) than a N1xx powder. It's this extra density/weight per volume that generates the higher MVs. Grain for grain however, you might find that the N1xx generates more energy than the N5xx equivalent. I'm guessing that 'High Energy' on the packaging sells better than 'High Density'. Also in terms of equivalence, my testing has shown that it's not as simple as saying that N550 is the double-base equivalent of N150 for instance.

Ultimately, in my experience, a barrel will demonstrate a preference for a particular powder, and if you ignore that preference or are ignorant of it, you'll waste a lot of time chasing your tail trying to develop loads with sub-optimal powders. Best case scenario the person posting on the internet might actually know what they are talking about (rather than just parroting information they took at face value from somewhere else) - but even then they can only tell you what worked well with their barrel. You are the only person who is in a position to figure out what works well with your barrel.

Best of luck!

Roonster

 

[Laurie]

Back in the day I reckoned a N155 would have been ideal, but then they announced N555 instead – which in theory should be ideal – but you'll lose about 1/3rd of your potential barrel life what with it being a double-base powder). Not really a deal-breaker for stalkers perhaps, but it's definitely a consideration for target/string shooters.

Look at Viht's powder data information tables and compare the specific energy for N555 against its N100 series powder equivalents - at a nominal 3,700 Joules per gram weight, it's identical to N140, and actually lower than N150.

N100 Smokeless Powders | Reloading | Handloading | Single base Rifle powder - Vihtavuori

N500 High Energy Rifle Powders | Reloading | Handloading | Gun powder - Vihtavuori

You contradict yourself with your second statement

"A wee word about Vhitavuori 'High Energy' (N5xx double base powders). In my testing I found that the single base N1xx powders were actually higher energy than the N5xx powders – but the N5xx powders were significantly higher density so you can pack way more N5xx powder into a case (by weight) than a N1xx powder. It's this extra density/weight per volume that generates the higher MVs. Grain for grain however, you might find that the N1xx generates more energy than the N5xx equivalent. I'm guessing that 'High Energy' on the packaging sells better than 'High Density'. Also in terms of equivalence, my testing has shown that it's not as simple as saying that N550 is the double-base equivalent of N150 for instance."

I suspect there are other rather different reasons why N555 has some nitroglycerine infused. Rather than create a 'hot' powder here (which other N500s can be), it seems likely that this is tied up with whatever method Viht is using to make its powders temperature-tolerant. N500 grades are now classed by the company as such across the range unlike the N100s, none of which have been added to the list. Recent additions such as 555 and 565 were in fact temperature-insensitive from their introduction.

Note too from the above tables that N555's bulk density is also lower at 900 g/ltr than N140/150's 910. In practice, there's likely no difference you'd notice. This also suggests that the nitroglycerine content is very low as it is infusing its molecules into the nitrocellulose base kernels that makes them heavier assuming kernel dimensions are common between the two type - which isn't always the case.

 

[Roonster]

Hi Laurie,

I often overhear/see conversations where someone will say that “N550 is just the double base version of N150”, or similar. It always involves the last two numbers being common, so N540 & N140, N560 & N160 etc. etc.

I believe this to be an oversimplification.

I’ve taken the liberty of plotting an infographic from Vhitavuori’s own load data for the 6.5mm Creedmoor and the 140gn ELD-M.

With respect to my comment about equivalence, and not being able to simply state that a N5xx powder is a double-base equivalent of N1xx powder, in this diagram N555 (red) seems to be an almost perfect progression of where N160 (purple) was going, whereas N560 (blue) plots entirely differently. I’ve never heard anybody say that N555 is the double base version of N160, for instance.

Also with regards to my comment about N5xx powders being 'high density' rather than 'high energy' I note that at 40.0gns N160 is producing a MV of 2,580fps, whereas N560 only produces a MV of 2,467fps. Likewise at 40.8gns, N160 is producing 2,618 fps whereas N560 is only producing 2,516fps. To get 2,618fps you would need 42.5gn of N560 to N160s 40.8gn. I have seen this phenomenon on a number of different plots, but I recently lost a great deal of my reloading data in a (self inflicted) computer blunder, so I can’t reference them right now.

These plots of course assume a linear relationship between charge wight and pressure, which may or may not be the case in practice.

@Laurie - I’d be interested to hear your thoughts on this, as I am perhaps misinterpreting the data, or guilty of oversimplification myself? I'm very keen to learn more about this topic, and any wisdom that you can share from your years of experience will be greatly appreciated!

Thanks,

Roonster.

 

[Laurie]

@Roonster I'd say the apparent contradictions mostly arise from the N100 and 500 versions having different burn rates. Viht says the pairs are the same in this respect, but as your graphs show they're not when it comes to actual applications. The 500 'version' is usually slower burning, so sometimes needs higher charge weights to achieve same MVs. In such cases, improved MVs become potentially available by using still higher charges (as allowed in the loads tables normally). Nevertheless, sometimes the N500 grade does give higher MVs with same weight charges, at least as charge weights approach the maximum for the N100 grade.

If you look at the kernel dimensions, they usually vary too between the two types in a given 'pair', so Viht obviously redesigned each powder to at least some extent changing the extrusion diameters and cut lengths as required to achieve the desired final effects of the nitroglycerin infused versions. In addition to the more dense chemical structure caused by adding nitroglycerine, this will in itself change the bulk density value to some extent. The higher value for N500s can be a major plus in smaller cartridges by getting more into the case before excessive charge compression occurs. See N500 vs 550 in 223 with heavier bullets in match loads here:

reach-out 7 – eu compliant powders by laurie holland

Also note that in the report on N140 and 540 in the same case / primer / bullet / rifle combination, 25.0gn N540 produced a 27 fps higher average than the same weight of N140. Unusually, there was also very little practical difference between the maximum usable charges (and not a lot in Viht's load data either) of these two grades in this application

To me, the two halves of the pairs are actually different powders in each case, but as each pair usually shares applications, the company quite sensibly treats them as a paired single grade, one half of which has been modified to increase energy / performance.