Viht N320 powder in a .410

[Windswept]

I know slow burning pistol powders are usually used in a .410 but whilst looking for some 2" data I noticed Gualandi list Viht N320 data for 2" . 410s. I've loaded some up and they work well but should I be at all worried about using a fast pistol powder? Ideally I'd like to reduce the load a tad to quiet them down. As N320 can be used for running very light loads in pistol cartridges (e.g. 3 grains in a 357) would there be any risk in reducing the published load a little? There's room in the case to keep the powder load up and increase the shot but I don't really need more than 9 grams of shot.

[Vince Green]

I would be very reluctant to make big changes but small changes gradually, with evaluation is the way to proceed. Oh and always keep notes.

good luck

[London Best]

Personally, with such a question, I would ask Vithavouri and not folk on a forum who may or may not know what they are talking about.

This is not aimed at the advice given by any individual member.

[enfieldspares]

I used N320 in a .38 Special. 4.0 grains or 4.5 grains from memory to make 850 fps from a 5" barrel Smith & Wesson pre-Model 27. Before the Tory handgun ban. I'd not have the least idea what would work in a .410" and, as others say, I'd ask of the makers.

Edited July 31, 2022 by enfieldspares

[Smudger687]

13 hours ago, Windswept said:

I know slow burning pistol powders are usually used in a .410 but whilst looking for some 2" data I noticed Gualandi list Viht N320 data for 2" . 410s. I've loaded some up and they work well but should I be at all worried about using a fast pistol powder? Ideally I'd like to reduce the load a tad to quiet them down. As N320 can be used for running very light loads in pistol cartridges (e.g. 3 grains in a 357) would there be any risk in reducing the published load a little? There's room in the case to keep the powder load up and increase the shot but I don't really need more than 9 grams of shot.

If it's a published load then it's irrelevant whether the powder is fast or slow - it's been tested and found to be safe. 

I would say you're fine to reduce the powder charge, providing:

1. The same components are used as the original full charge load
2. The arrangement of these components are used are the same as the original full charge load
3. Compressible fillers such as cork wads are used to ensure your stack height is the same as the full charge load

Subject to the above conditions, a reduction in powder charge will almost invariably lead to a reduction in chamber pressures, but it's worth remembering that powders actually need some pressure to burn properly - if you reduce the charge too much the powder won't ignite and you may end up with a barrel blockage. 

 

[Windswept]

I will email Vihtavuori but doubt I will get much back. It always puzzled me why powder manufacturers don't publish more data, Vihtavuori do list some shotgun data but only 3" 12 guage. Not only is .410 not as popular but 2" cases even less.

 N320 is still widely used today for .357 loads for LBRs and gallery rifles, often running power charges than the minimums Vihtavuori suggests. Hence my reasoning that there shouldn't be any risk in reducing a small .410 load.

[Windswept]

41 minutes ago, Smudger687 said:

If it's a published load then it's irrelevant whether the powder is fast or slow - it's been tested and found to be safe. 

I would say you're fine to reduce the powder charge, providing:

1. The same components are used as the original full charge load
2. The arrangement of these components are used are the same as the original full charge load
3. Compressible fillers such as cork wads are used to ensure your stack height is the same as the full charge load

Subject to the above conditions, a reduction in powder charge will almost invariably lead to a reduction in chamber pressures, but it's worth remembering that powders actually need some pressure to burn properly - if you reduce the charge too much the powder won't ignite and you may end up with a barrel blockage. 

 

Thanks for that, I'm using an overshot card, then two 1/2" fibre wads to get the height right. Then shot, overshot card and RTO, that's a little tight so a small reduction in powder would be ideal. 

They are to be used in a single shot gun and I'm used to checking for a clean bore. Although I'm aware of small charges not burning correctly I think I'd have to dramatically reduce N320 before I would see any problems but worth knowing the risks.