Bismuth question

[Powersgt]

I’ve tried to ask this on “Duck hunting chat” but it won’t let me upload a question. Maybe someone here can answer a dumb question?

’ll try this again,

I’m new to shotgun reloading but I have great deal of metallic reloading experience. I’ve recently purchased a nice Spanish made 10ga. double with full chokes. It will cost as much as I paid for the gun to have removable chokes put in so so in the mean time I was going to reload bismuth shot. ( I know, I’m money ahead just choking it but what’s the fun in that? I’ll do it later.)

Question: I’ve read that bismuth is approximately 15% lighter than lead? So if I use the same size bushing as I would for lead then my payload weight would be15% less. Ex. 1oz. of measured lead would be .437+/- grains and the same measured bismuth would be .371+/- grains. So if that’s the case, should I change the powder weight to match the payload weight? Or should I just fallow the recipe and load it as published?

Thanks,

Powersgt

[Hogtamer]

Weigh your charge and load accordingly....no use to guess if you have a scale.

[Powersgt]

Weigh your charge and load accordingly....no use to guess if you have a scale.

Yes, I do but what I’m trying to ask is if you have a volume of shot that fills the wad according to the recipe and it ways less then say one ounce then do you adjust the powder charge for payload weight?

[Hogtamer]

a little difference won't matter...i.e. 1/16 oz lighter payload = slightly more velocity. Would adjust load for 1/8 oz or more heavier payload.

[Winger Ed.]

I'd load it with the powder & shot bushings for the Lead shot load.
The shot charge is lighter, so it'll go out a little faster.

Being lighter, it'll also slow down in flight faster than Lead.
With the extra speed, you might make up the effective range for it slowing down sooner.
It should have more or less the same range & pattern as the lead load, at almost the same or maybe a little less pressure.

[Powersgt]

a little difference won't matter...i.e. 1/16 oz lighter payload = slightly more velocity. Would adjust load for 1/8 oz or more heavier payload.

Makes sense, similar to loading cast bullets of different alloys.

[Powersgt]

I'd load it with the powder & shot bushings for the Lead shot load.
The shot charge is lighter, so it'll go out a little faster.

Being lighter, it'll also slow down in flight faster than Lead.
With the extra speed, you might make up the effective range for it slowing down sooner.
It should have more or less the same range & pattern as the lead load, at almost the same or maybe a little less pressure.

That makes perfect sense; I did a little more load comparison between lead and bismuth. Looks like in two similar loads, the data shows a 1/4” wad in the lead load column and no undershot wad in the bismuth which tells me the difference is made up in volume and the powder charge is different as well.

Thank you for the replies Hogtamer and Winger Ed.

V/R

Powersgt

[megasupermagnum]

Is this gun a 3 1/2" chamber? If so, let me recommend the following load. This is load data straight out of the Lyman shotgun manual.

Remington 3 1/2" hull
Remington 209 primer
36 grains Bluedot
BPI BPD-10
1/4" 16 or 20 gauge felt wad under shot
2 ounce bismuth
PSB buffer
fold crimp

This load ran about 1215 fps from my Ithaca Mag10.

Warning, the following is not published load data.

Now if you are ok with a non-book load, I changed the above load for two reason. #1 BPD-10 wads are way too expensive. #2 I always like SAM1 wads better, and in this case they even pattern better. I have the Pressure Trace II system, and found that the following load is right at 11,000 PSI MAP recommended by SAMMI for 10 gauge 3 1/2" guns. The above listed load ran just over 10,900 PSI. I had nothing else to compare to, so my system calibration could be off, but if the above book load is safe, the below load is safe.

Remington 3 1/2" hull
Remington 209 Primer
37 grains Bluedot
RSI SAM1 wad
1/8" 16 or 20 gauge felt wad under shot
2 ounces B bismuth
PSB buffer
1/8" 12 gauge cork wad
fold crimp

You may add or remove spacers to fit. I think this ran about 1250 FPS in my Ithaca Mag10. It patterns very well. There is nothing wrong with backing off to 36 grains Bluedot either. Mine is a fixed full (actually over full), I wouldn't have it any other way. I would leave your gun alone.

Now to answer your question, it has been found that if you substitute equal volumes of bismuth in place of lead in data, and it usually produces similar or lower pressure. The best way is to use bismuth specific data though. The only time I used a shot bushing for bismuth, I believe I used a 1 1/4 oz bushing, and it dropped very close to 1 1/8 oz of bismuth shot. I'm not sure if that helps or not.

The only correct answer is to use actual bismuth specific data, but if you have to use lead shot data, substitute equal volume of bismuth, and do not change the powder charge. You are not likely to get your best loads this way.

[6pt-sika]

I load Bismuth in the 10 gauge 2 7/8” and in the 12 gauge 2 3/4” . In the 10 gauge I load 1 1/4 of lead but it requires a spacer to fill the shotcup so when I load Bismuth I WEIGH 1 1/4 ounces and leave the spacer out . In the 12 gauge I use 1 1/4 ounce lead load data and WEIGH out 1 1/8 ounces of Bismuth . Now I will say both my loads are low pressure so that most likely helps , but both will darn sure anchor a goose if I do my part . Eventually (if I live long enough) I’ll take geese with 16 , 20 and 28 gauge Bismuth loads in my old doubles .