Black powder capacity of 12 gauge high brass shells?

This query concerns whether a rifled 12 gauge slug shotgun can be loaded with black powder, to function like Victorian-era "bore" sized rifles. How much Swiss [brand] FFg powder - in weight in grains - can be put into the base 1.45 inches of primed unloaded new or once-fired, 12 gauge 2.75-inch high-brass shotshells? I specify Swiss black powder because it is denser than other black powder brands generally available. Being more dense might mean that more volume, and perhaps more weight, can be measured into the cylindrical shape. I'm not asking about any additional capacity that might occur by compressing the powder or using a drop tube. I just want to "get in the neighborhood." Other than high brass rather than trap/skeet shotshells, I'm not fixed on any particular brand or other specifics.

I would start with the old by-law... equal measure by volume of shot and powder. Weigh the slug, find out how much powder will equal by VOLUME. A trick I have used is weigh the slug first. Then use use an old dipper of some sort. I use one of these....
Attachment 229747
Fill the dipper with an equal weight of lead shot. Those type dippers are adjustable in height so when it is level full and the weight is equal to the slug weight, you will have your volume measure of BP.

I use an electronic scale to pour the shot into to weigh the shot to find the equal weight/volume. I take my scale with a powder cup, weigh the slug on my electronic scale inside the powder cup, then remove the slug and start filling the shot till it is equal to weight in the powder cup on my scale. Once that is done, I adjust the dipper thingy out till all the shot in the Powder cup fits level full in my dipper. Wince the dipper is full with all the shot, I pour out the shot from the dipper, fill the dipper with BP and weigh it in grains and write it down... that is the starting amount of BP to use with any load. That is how most BP loads are figured and how our forefathers did it..

I would also use all Brass shotshells. New ones can be had now made by CBE if memory serves. BP tends to burn holes in plastic shells. I do them like this...

Attachment 229748

Hope that helps,
Marko

I use the 1-1/8 shot bar hole on a MEC Junior to load the powder. Gives me about 60 grains. Then use WAA12R wad with Lee 1 oz. slug. I consider them to be for one shot only and then toss the hull. Have not chronoed them.

Here are some guidelines for you:

http://www.tbullock.com/bpsg.html

I loaded up modern plastic hulls with 4 drams of FFFg BP under 12 pellets of 00 buckshot with no ill effects and shot lots of 0.690" RB's and 1 1/8 oz. shot loads over the same charge. Since Tom Bullock shows a "heavy" load is 3 1/2 drams under 1 1/4 oz. shot I was into "heavy" territory but again, no ill effects. The 0.690" RB is only about 1 1/8 oz. though so a little lighter payload.

I concur with Mr. Bullock's comments about BP being hard on plastic hulls.

Also, I found that plastic wads either melted or scraped off on BP fouling (or maybe some of both) and left a mess of plastic in the bore so be warned that may happen. Lubed felt or fiber wads may eliminate or at least reduce both BP and plastic fouling.

YMMV

Longbow

Modern rifled shotgun barrels have a relatively fast twist being designed to shoot saboted shotgun slugs. Finding full-bore size slugs is a real problem unless one gets a custom made bullet mould. I have both a 20 and 12 gauge rifled shotgun in which I shoot slugs and round ball using black and smokeless powder. I too have found that plastic hulls often burn through using black powder. Paper hulls do also, just not as fast. Plastic shot sleeves leave a lot of plastic fouling in my rifled bores. All brass shells are perfect for black powder loads but have a larger inside diameter than plastic or paper hulls. In order to shoot a .735 (595 grain) round ball in an all 12 gauge brass shell I have had to wrap it in a greased .016" pillow ticking patch to center it. I have fired these over anywhere from 2.5 drams (60 grains) to 4 drams (110 grains) of Olde Eynfsord 1& 1/2Fg black powder with good results despite the 1 in 30 inch rifling twist. No surprise that the lighter loads shoot more accurately and have less recoil. The recoil with the 4 dram load is not for the fain of heart!

Markopolo I like they way your slug loads look. Just wondering though, loaded that way aren't you leaving a lot of air space between the powder and slug? Or are you using a felt wad or something like that over the powder? Thanks!

27 grs. to a dram approximately, 4 1/2 drams is max. for the 12 gauge, do the math.

Mr Sharps... nitro card and felt wads made by Alcan... you can also get them from CircleFly.... they have to be 11 gauge if you want them to fit. I have also found that 10gauge wads fit nicely into all brass shells. The Remington SP10 is a nice ticket for shot, and you can build up a nice colum as well for the lee Slugs..
Attachment 230861

Quote:

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Originally Posted by MT Chambers

27 grs. to a dram approximately, 4 1/2 drams is max. for the 12 gauge, do the math.

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Why?

I load 135-140grains of Swiss behind a .736" round ball in 2.4" Magtech brass all day long and so far my wall paper has stayed in place!
I would load hotter if there were room for it!

The dram equvivalent is just a guideline to keep loads in the same ballpark speed wise. Not a set max. ie. do not exceed line.

Quote:

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Originally Posted by Naphtali

This query concerns whether a rifled 12 gauge slug shotgun can be loaded with black powder, to function like Victorian-era "bore" sized rifles. How much Swiss [brand] FFg powder - in weight in grains - can be put into the base 1.45 inches of primed unloaded new or once-fired, 12 gauge 2.75-inch high-brass shotshells? I specify Swiss black powder because it is denser than other black powder brands generally available. Being more dense might mean that more volume, and perhaps more weight, can be measured into the cylindrical shape. I'm not asking about any additional capacity that might occur by compressing the powder or using a drop tube. I just want to "get in the neighborhood." Other than high brass rather than trap/skeet shotshells, I'm not fixed on any particular brand or other specifics.

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Dont have any of them so i did the next best thing and measured what i have.
2.4" Magtech will hold @180grains of Swiss #2 to the 1.45" line
12 Gauge made from 50BMG will hold @145grains to the 1.45" line
Both measured from the bottom of the cavity.

So a WAG would be somewhere around 160+ grains in your brass.

Just realised you are probably talking about plastic shotshells right?
Then all bets are off as they are most all different in internal construction.
I took a high brass 2.75" Cheditte plastic shell and it will hold @168grains to the 1.45" line.

Back in the day, 4 1/2 drams was considered max. with BP, to day shotshells are marked with dram equiv. and guess what? 4 1/2 dram equivalent is still considered max. In the original BP loads I believe it had more to do with speeds and patterns not pressure.