OK, here goes nothing..... I have been talking to a few guys and have found out that in large capacity cases (400+ grains) that they have used a Black powder charge near the primer to help ignite the main powder charge in slow burning powders (WC872). Does anyone have any experience with this? How much BP to use? how to place it? How much does this affect chamber pressures? Just to name a few questions....

Craig

Ross Seyfried claims that this is a good way to ruin a double rifle, as pressure can be erratic and very high. Haven't tried it myself; figure that's what Federal 215s are for.

Out of curiosity, what on God's green earth has a 400+ grain capacity, short of a field piece?

I have been playing around with Russian 14.5 and 20mm Lahti. Looking to verify information. I dont like playing around with stuff that close to my head. So I ask first. Better safe than sorry.

Gotcha. Anti-tank cannon are a bit out of my league, however, so I'll leave the field to the more knowledgable folks.

M_S, you need to go to a reenactors website, or one that deals with war weapons. I doubt anyone here would know, or even be interested in such firearms! About the largest thing we use here would only hold about 120 grs of smokeless with a 750 gr bullet. I suspect, however, you, or the person who gave you the info, are thinking of the use of a small amount of fast burning SMOKELESS powder, over the primer to start the burn of large charges of slow burning somkeless, or BLACK POWDER, not the other way round! I'd ask in a more appropreate web-site however, before trying it either way!

Some blackpowder cartridge shooters of my acquaintence use a kicker (booster) charge of a fast burning smokeless powder in some of thier loads and usually for times when the temperatures are below 0 farenheit.

Contact Lapua or a major arms factory that has an ordnance division and ask to talk to one of thier tech people and present your question too them, believe me they know.

Try anyone of the various 50 BMG shooting clubs/association, since many of them also play with things approaching artillery and in some case actual artillery, there is a wealth of knowledge out there and people who have been loading for these big boys while rare are dedicated.

The only place I have heard of black being used for a charge of smokeless is in the 16" guns on the Missouri class battleships. I do not know for sure if this is true, or if anyone used it in little bores like shoulder fired rifles, but could be true I suppose.

Brent

Two main reasons for duplexing black powder with a small charge of fast burning smokeless are to improve ignition of a heavily compressed charge of black powder, which tends to form a solid mass under compression and, more commonly, to reduce the amount of fouling left in the barrel.

No more than 10% of total charge should be smokeless, with the equivalent weight of black removed from the charge. Approximate ration of 1gr smokeless = 3gr Black so only a small increase in performance will be experienced.

Don't know why anyone would use a starter charge of black powder behind smokeless - would only reduce performance and add hydroscopic crap to the fouling in the barrel.

I saw some articles on this in WWII-era 20MM rounds. Another discussion on the GOW site is at http://guns.connect.fi/gow/QA18.html

It was done to eliminate hang fires, although a fast-burning powder is considered better.