Vhitavouri N550

[ront]

Moving over to N550 powder and a 130 Berger VLD in Tikka TX3  6.5CM Super Varmint.  Anybody using this powder and bullet? What sort of results are you getting? Any advice on powder charge?

Thanks in advance.

[phaedra1106uk]

Start with the Viht load data,

https://www.vihtavuori.com/reloading-data/rifle-reloading/?cartridge=95

I use N150 in LRP cases with 139 Scenars, works very nicelty indeed.

[ront]

Good to hear from You.  Do you use small or large primers and do you think it makes any difference? What sort of groups are you getting? And did you try any other powders?

[Laurie]

23 hours ago, phaedra1106uk said:

Start with the Viht load data,

https://www.vihtavuori.com/reloading-data/rifle-reloading/?cartridge=95

I use N150 in LRP cases with 139 Scenars, works very nicelty indeed.

 

 

Agree with this.

 

BUT note that Viht's data are for small primer Lapua cases. The quoted maximum loads may be well over-pressure when large primer / 2mm flash-hole brass is substituted. (.... and the days when Viht's maximum loads were low/mild have long gone. Those added in recent years are often very heavy indeed.)

[ront]

Thank you for advice.  I have the Vhit reload data and will be using CCI 450 small magnum primers.  Will have to work up a load in fired lapua cases and will be using Redding type S dies and a Stoneypoint comparator for shoulder bump. Will start with a middle weight of powder and work on seating depth first.  Any signs of pressure and I can back off powder charge.  If I find a sweet spot with seating depth I can then refine the powder charge. Any tips or advice on the above would be welcome as I am always learning.

[pengo]

23 hours ago, Laurie said:

 

 

Agree with this.

 

BUT note that Viht's data are for small primer Lapua cases. The quoted maximum loads may be well over-pressure when large primer / 2mm flash-hole brass is substituted. (.... and the days when Viht's maximum loads were low/mild have long gone. Those added in recent years are often very heavy indeed.)

Hi Laurie,

That’s a good point, that I hadn’t considered before, but I also include Quickload in my calculations, just to help a bit more.

[Laurie]

1 hour ago, pengo said:

Hi Laurie,

That’s a good point, that I hadn’t considered before, but I also include Quickload in my calculations, just to help a bit more.

 

If there's one bit of advice I'd give people on Viht N550, it is NEVER, EVER trust QuickLOAD calculations with it!

QL seriously underestimates pressures / overstates usable charge weights. N550 is apparently much 'quicker' than either burn rate tables or QL show.

Have a look here for N500 series powders in 260 Rem, and scroll down to 'Bonus Fourth' for N550.

 

https://www.targetshooter.co.uk/?p=3483

 

This was QL v.3.6, but the latest V.3.9 continues to get this powder badly wrong.

[Scotch_egg]

I’ve got a few kilos of N550 I’m tempted to use after just taking a look at the viht tables. 
 

 

[Laurie]

1 hour ago, Scotch_egg said:

I’ve got a few kilos of N550 I’m tempted to use after just taking a look at the viht tables. 
 

 

 

It's an excellent powder with lots of applications. Don't load it too heavily though, as like most N500s it can be hard on barrels with full-pressure loads.

[Scotch_egg]

1 hour ago, Laurie said:

 

It's an excellent powder with lots of applications. Don't load it too heavily though, as like most N500s it can be hard on barrels with full-pressure loads.

Thank you Laurie. I suffered my first carbon ring at the weekend. The rest of the bore didn5 look too bad though. This is in a 7mm SAUM. 
 

I’ll give it a go in the creed. 

[phaedra1106uk]

@Laurie

I'm fairly certain that when Viht changed the wording on their data to "Small Rifle" a few years back they didn't change the actual load data at all.

I was already loading 36gr of N150 with the 139 Scenars when the max was listed as 35.5 and it's still listed as that now.

I did try it with SRP cases (StarLine) but got delayed or even partial ignition in the colder weather, no problems using N160 but that was probably due to a higher case fill (42.1gr).

[Laurie]

@phaedra1106uk

 

IIRC Lapua introduced this case in SP form alone, and it was only later that the company added the large primer version, therefore Vihtavuori needed to differentiate the two types. Company loads data generally come with so little background data, they are often quite opaque as to what assumptions have been made about what the handloader might or might not use in the way of components. At one time, the US bullet and powder companies always added the rider that the data applied to the exact components specified and those alone. Change a single item and you were on your own. Such warnings have disappeared, probably because most people either never read them, or ignored them, and anyway there isn't room for proper data, advice, and background information nowadays when few customers buy reloading manuals and rely on absolutely basic information from apps and Internet web pages. Relatively few companies provide their measured pressures, so if the others decide either to load up to a few hundred psi short of the SAAMI or CIP MAP on the one hand, or knock charges down enough to reduce them by a few thousand psi, we're simply left in the dark, and are sometimes surprised by actual MVs and/or pressure indications when we use their data.

I'm currently grappling with this issue working up a powder test series (as H4831 alternatives) in 6.5X55mm SE. There is such confusion over allowable maximum pressures, and so little information given about what the testers/manual compilers have assumed to be the max pressure, that there are huge variations in max loads. The only pressure indications given are from Hodgdon whose loads stay within the modest US SAAMI 46,000 CUP, and the old Accurate Arms printed manual (now Lovex) which tested contemporary Norma factory cartridges using a modern Piezzo crystal pressure barrel set-up and got a maximum factory pressure of 51,000 psi using the US measurement protocols (likely a couple or three K higher psi under the CIP measurement method). The result is up to 5gn variations in maximum charges for 4831 class powders. (Yes, I know Viht provides two data sets - 'Swedish Mauser' and SE/SKAN. One can assume that the SE loads produce ca. 55,000 psi in Viht's test barrels, and that the lower level are generally safe in M1894/96/1938 Mausers ........ but what max pressures were assumed as 'safe'?)

On SRP unsatisfactory ignition in Creedmoor / 308 capacity cases, I've long come to the conclusion that the marginal efficiency of the ignition set-up makes these cases very powder grade sensitive (and also, but possibly to a lesser extent primer model sensitive). When I say grade, I mean just that - ie individual grades not all grades across a manufacturer's range. I've found SRP 308 ignition marginal with Viht N140, but it works fine all else being the same with N150 and N160 (7mm-08 for N160). Small samples in my testing, but I've seen the odd bit of gossip that says one top US F/TR team preferred N140 in 308 with the 185gn Berger Juggernaut, but would only use Lapua large primer brass after testing both types.   

 

 

[Scotch_egg]

Viht load data changed a few years ago with very conservative top end. So much so I got serious issues with my 6mm creedmoor and N150 I posted about the issue of sooty cases around the rim. Very odd indeed. Yet with RS62 I achieved excellent accuracy and no issues with soot. I’m yet to chrono the load.