April 28th, 2020

Vihtavuori Explains Powder Grain Shapes

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders

POWDER GRAIN SHAPES — What You Need to Know

The shape of powder grains has a profound effect on the performance of the powder charge, as it concerns both pressure and velocity. There are multiple powder shapes including flake, ball, and extruded or “stick” (both solid and perforated).

All Vihtavuori reloading powders are of the cylindrical, single-perforated extruded stick type. The differences in burning rate between the powders depend on the size of the grain, the wall thickness of the cylinder, the surface coating and the composition. Cylindrical extruded powders can also have multi-perforated grains. The most common types are the 7- and 19-perforated varieties. A multi-perforated powder grain is naturally of a much larger size than one with a single perforation, and is typically used for large caliber ammunition.

Other types of powder grain shapes include sphere or ball, and flake. The ball grains are typically used in automatic firearms but also in rifles and handguns. The ball grain is less costly to produce, as it is not pressed into shape like cylindrical grains. Flake shaped grains are typically used in shotgun loadings.

Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders

Web thickness in gunpowder terminology means the minimum distance that the combustion zones can travel within the powder grain without encountering each other. In spherical powders, this distance is the diameter of the “ball”; in flake powder it is the thickness of the flake; and in multi-perforated extruded powders it is the minimum distance (i.e. wall thickness) between the perforations.

The burning rate of powder composed of grains without any perforations or surface treatment is related to the surface area of the grain available for burning at any given pressure level. The change in the surface area that is burning during combustion is described by a so-called form function. If the surface area increases, the form function does likewise and its behavior is termed progressive. If the form function decreases, its behavior is said to be degressive. If the flame area remains constant throughout the combustion process, we describe it as “neutral” behavior.

The cylindrical, perforated powders are progressive; the burning rate increases as the surface area increases, and the pressure builds up slower, increasing until it reaches its peak and then collapses. Flake and ball grains are degressive; the total powder surface area and pressure are at their peak at ignition, decreasing as the combustion progresses.

So how does the shape affect pressure and muzzle velocity? In general, it can be said that powder that burns progressively achieves a desired muzzle velocity at lower maximum pressure than a powder that burns neutrally, not to mention a degressive powder. As grain size increases, the maximum pressure moves towards the muzzle, also increasing muzzle blast. Muzzle velocity and pressure can be adjusted by means of the amount of powder or loading density, i.e. the relationship between the powder mass and the volume available to it. As the loading density increases, maximum pressure grows.

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Vihtavuori loading propellant reloading powder N133 N150 N140 N550 ball flake stick extruded perforated powders


This article originally appeared on the Vihtavuori Website.

Permalink Bullets, Brass, Ammo, Reloading, Tech Tip No Comments »
December 26th, 2017

Vihtavuori Rolls Out Major Reloading Data Update

VV Vihtavuori finland powder propellant reloading recipe data information mobile app

VV Vihtavuori finland powder propellant reloading recipe data information mobile appVihtavuori offers free reloading data online, and through a free Mobile App. And now those resources are even better — Vihtavuori has completed a significant enhancement of its reloading information for hand-loaders. First, the Finnish powder company has added the new N565 powder to the data tables. But that’s just for starters.

A massive update has been completed with new bullets added for dozens of popular calibers: “We are happy to announce the addition of more than 130 lines of reloading data, with bullets by Barnes, Brenneke, Lapua, Berger, Sierra, Woodleigh, Hornady, Nosler and LOS”. The updated online information supplements the online Reloading Databases, which has dedicated sections for Rifle Cartridges, Pistol Cartridges, and Cowboy Action.


Rifle DATA | Pistol DATA| Mobile APP



POWDER MAKING: This video shows how Vihtavuori powder is produced:

NEW Cartridges Added

Vihtavuori’s latest December 2017 Load Data update includes information for these new cartridge types and bullet types:

.300 Norma Mag:
– Lapua 185grs / 12.0g
– Berger 215grs / 13.9g
– Lapua 220grs / 14.3g
– Berger 230grs / 14.9g

8x68S:
– Sierra 150grs / 9.7g
– Lapua 180grs / 11.7g
– Nosler 180grs / 11.7g
– Nosler 200grs / 13.0g

EXPANDED DATA for Many Cartridges

With its December 2017 load information update, Vihtavuori now offers data for the following chamberings and bullet weights:

7x57R:
– Barnes 150grs / 9.7g
– Brenneke 150grs / 9.7g
– Lapua 150grs / 9.7g
– Lapua 160grs /10.4g
– Barnes 174grs / 11.3g

7×64:
– Swift 140grs / 9.1g
– Barnes 150grs / 9.7g
– Sierra 174grs / 11.3g
– Brenneke 177grs / 11.5g
– Lapua 181grs / 11.7g

7 mm Rem Mag:
– Berger 180grs / 12.6g
– Berger 194grs / 12.6g

.308 Winchester:
– LOS 140grs / 9.1g
– Hornady 150grs / 9.9g
– LOS 150grs / 9.9g
– Woodleigh 150grs / 9.9g
– Berger 155grs / 10.0g
– LOS 155grs / 10.0g
– Sierra 155grs / 10.0g
– Hornady 165grs / 10.7g

.30-06 Springfield:
– Sierra 168grs / 10.9g
– Berger 185grs / 12.0g
– Woodleigh 240grs / 15.6g

8x57IS:
– Sierra 201grs / 13.0g

.338 Lapua Mag:
– Berger 250grs / 16.2g
– Lapua 250grs / 16.2g
– Barnes 280grs / 18.1g
– Berger 300grs / 19.4g

.300 Win Mag:
– Hornady 165grs / 10.7g
– Sierra 168grs / 10.9g
– Berger 200grs / 13.0g
– Barnes 200grs / 13.0g
– Woodleigh 200grs / 13.0g
– Berger 215grs / 13.9g
– Berger 230grs / 14.9g

.38 Special:
– H&N 157grs / 10.2g

9 mm Luger:
– H&N 145grs / 9.4g

Vihtavuori story tip by EdLongrange. We welcome reader submissions.
Permalink Bullets, Brass, Ammo, News, Reloading 1 Comment »
July 21st, 2011

Vihtavuori Reloading Data Updated for Seven Cartridge Types

If you read our 2011 Super Shoot Report by James Mock, you’ll see that Vihtavuori N133 powder is the overwhelming choice of top short-range benchrest shooters for loading their 6PPCs. Other Vihtavuori powders, such as N135, N150, and N550 are also very popular for other match and hunting cartridges.

If you currently use a Vihtavuori (VV) powder, or you plan to try a Vihtavuori powder in the near future, visit www.Lapua.com soon. Load info on Lapua’s Vihtavuori Reloading Data Page has been updated (or added) for the following calibers: .222 Remington, .223 Remington, .223 WSSM (new caliber data), .22-250 Remington, 6.5 Grendel, 6.5×47 Lapua, and 7.62x53R. In the updated tables, you’ll find VV powder recipes for a wide variety of bullets from Hornady, Lapua, Nosler, Sierra, Speer and other bullet-makers.

Though these recipes are fairly conservative, always start low and work up gradually when using a new powder for the first time. Likewise, you should back off your load if you change ANY component or if you have fitted a new barrel to your rifle.

Vihtavuori N100 Series
The N100 series powders are single-base powders used mainly in rifle calibers. There are ten N100 series powders with different burning rates and suitability from the .17 Remington up to the .458 Winchester Magnum and two special powders for .50 BMG.

N500 Series
The N500 series powders are impregnated extruded rifle powders with Nitroglycerol added as extra energy component. If higher loading densities and more energy are needed, N500 series powders are competent alternatives for the N100 series powders. N500 series High Energy powders are available in five different burning rates.

Story tip by EdLongrange. We welcome submissions from our readers.
Permalink News, Reloading 5 Comments »