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Alpha1 wrote:

Ovenpaa wrote:The Viht double base powders can be quite hot and having burn the throat out of a few 7mm SAUM and .308 Win barrels I tend to not use the them for short distance stuff. My view is it is not until around 800 yards that the debatable benefits of the N5xx series powders need be considered.[/quote)

What powders do you normally use.

I use Viht N150 in my 6.5x47 Lapua with 123gr Scenar's, so I imagine this could be suitable for 6.5 creedmoor. I lose around 50fps compared with double based powder Reload Swiss RS60 (I haven't used N550 so please forgive the apple to pears comparison). Still, a 123gr bullet at ~2,900fps is fast enough for me!

As a matter of interest, what's the barrel length? Mine's 29", and using 40 grains of RS50, I get 2980fps with 123 Scenars.

Pete

WelshShooter wrote:

Alpha1 wrote:

Ovenpaa wrote:The Viht double base powders can be quite hot and having burn the throat out of a few 7mm SAUM and .308 Win barrels I tend to not use the them for short distance stuff. My view is it is not until around 800 yards that the debatable benefits of the N5xx series powders need be considered.[/quote)

What powders do you normally use.

I use Viht N150 in my 6.5x47 Lapua with 123gr Scenar's, so I imagine this could be suitable for 6.5 creedmoor. I lose around 50fps compared with double based powder Reload Swiss RS60 (I haven't used N550 so please forgive the apple to pears comparison). Still, a 123gr bullet at ~2,900fps is fast enough for me!

20190512_210352-1612x1209.jpg

The Creedmoor and 260 Rem cases have significantly larger capacity over the 6.5X47L over the same bore area and bullets, so this changes the internal ballistics and hence suitable powders.

Some people have had excellent results from the Creedmoor with N150; others excellent results from slower burning N160. To date, I've yet to meet anybody who obtains equally good results with both, in fact the poorer one is often not just inferior, but simply bad.

This is almost certainly why Nammo Vihtavuori has introduced N555, to fill a gap in the existing range. Thanks to the huge American shift towards the 6.5s and away from 30s among high-round count users and handloaders, H4350 and its equivalents have become much more commercially important and US forums are full of threads complaining about H4350's scarcity and possible replacements. Hence the rush to get good alternatives onto the market. In the US, Alliant Re16 is taking a lot of business away from former H4350 users, IMR-4451 is a near straight 4350 replacement, and Viht is plainly entering the arena with N555.

Incidentally, Viht's (and most other companies') comparative burning rate quickness tables show N150 as equivalent to IMR-4350, and N160 to IMR-4831. I'm sure this is misleading in most applications in that N160's rate is much closer to that of the 4350s than 4831 in most cartridges which puts N150 on the 'quicker' side of the 4350 group. The exception to this rule in rate charts is Norma's which instead of 'closed bomb' laboratory test results uses a single charge weight and common components in a 308 Win load giving relative MVs and Pmax values against IMR-4350 which is rated at 100. Norma's method gives N150 a relative MV of 115.7 against IMR-4350 and relative pressure of 118.0. (N160 is 102.1 / 107.5 respectively making it a modest amount 'quicker' whilst H4350 is a tad 'slower'.)

https://www.norma-ammunition.com/en-gb/reloading-data