Substitute Unique with Bullseye?
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Bullseye's a lot faster and there's no universal conversion factor for the two. You can work up a load starting with 75% as much Bullseye, and stop when you reach 80-90% of the MV you got with the Unique load. That's what I've done anyways (but not with the 400 CorBon).
hatman1793
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Don't!
Don't use Bullseye in 400 Corbon. Its way too fast. That caliber needs a medium burning powder or something on the very edge of something slower. Seen a Unique load that works. That is a specialiality caliber that most people have little experience with...
Don't use Bullseye in 400 Corbon. Its way too fast. That caliber needs a medium burning powder or something on the very edge of something slower. Seen a Unique load that works. That is a specialiality caliber that most people have little experience with...
It's best to start with the starting load.
As for Bullseye not being suitable for the 400 CorBon cartridge, wouldn't it be more correct to say it isn't suitable for the semi-auto firearms that shoot it? I assume that the firearms require a slower powder to cycle correctly.
Unique is a wonderful general purpose powder. It works well at high preesure and at low pressure. Hence its name. It has been around since 1900 (i remember it being introduced) and is still very useful.
if you could only have one powder for all applciations, this would be a good choice.
Bullseye is very fast and not suitable for adapting to other purposes.
if you could only have one powder for all applciations, this would be a good choice.
Bullseye is very fast and not suitable for adapting to other purposes.
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Don't #### around with a powder as fast as Bullseye. Doesn't take much of this stuff to overload just about anything.
Best get some proper load data, and start with a powder intended for the cartridge.
Best get some proper load data, and start with a powder intended for the cartridge.
See post #12 here:
http://www.castbulletassoc.org/forum/view_topic.php?id=486&forum_id=22
Ed Harris, of "Ed's Red" fame, has come up with a couple rules of thumb for using Bullseye where published Unique data is available for a given bullet weight and type.
http://www.castbulletassoc.org/forum/view_topic.php?id=486&forum_id=22
Ed Harris, of "Ed's Red" fame, has come up with a couple rules of thumb for using Bullseye where published Unique data is available for a given bullet weight and type.
Pretty much exactly what I said, and I hadn't seen that. I based what I said on experience, but admittedly not with the 400 CorBon (just a necked-down 45 ACP).
For those who would say you can't use Bullseye in some cartridges - nonsense. There isn't a cartridge that exists for which you can't produce a safe Bullseye load. I didn't say good, as it is best suited to very small cartridges, or low velocity light bullet loads, but safe for sure. It's not often well suited to semi-autos either as it's pressure curve might not be compatible with what's required to cycle the action. If it works with semis using 45 ACP, I would not dismiss it for the 400 CorBon. It almost certainly won't be the best powder though, or there'd be plenty of loads for it floating around.
If you're one of the guys who believes that you should only use published loads (it's dangerous!!!), you're missing out on a lot of interesting loading experimentation.
No, no, no - drinking is dangerous! Mondays and Thursdays are the days I check headspace on all my guns. If I have time I'll get a headstart my Tuesday and Friday tasks - pulling the powder from my handloads, confirming the weights and removing a grain. 
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What Andy said above, about Bullseye being useful in most cartridges is true, it's speed, and easy ignition make it a natural for reduced loads as an example.
I have a problem with blindly throwing out a percentage conversion however. Case volumes make powders burn at different rates.
There is however a big fear attached to Bullseye, and that's just the internet. It's just another powder, albeit one of the fastest, and dirtiest you can buy.
I have a problem with blindly throwing out a percentage conversion however. Case volumes make powders burn at different rates.
There is however a big fear attached to Bullseye, and that's just the internet. It's just another powder, albeit one of the fastest, and dirtiest you can buy.
I agree with what you have said, but the conversion factor is not blind - it's based on known Unique loads and proven across multiple cartridge sizes, and then reduced a bit for safety. The "75%" could be 75% for some cartridges and 90% for others.
Here's the Litmus Test - can anyone name a single example where using 75% of a published Unique load would be dangerously high?
We do powder conversions all the time based on relative burn rates and published load tables, we extrapolate, test and repeat.
Here's the Litmus Test - can anyone name a single example where using 75% of a published Unique load would be dangerously high?
We do powder conversions all the time based on relative burn rates and published load tables, we extrapolate, test and repeat.
Here's another way to look at it:
- you can safely use 40 S&W max loads, as it's a smaller case, and using the larger 400 CorBon case will lower pressures; and
- you must remain below 45 ACP max loads, as it's the same case, but the 400 CorBon has a smaller bore.
With a 180 gr as an example, for Bullseye (from the Alliant website), this puts you in a narrow band between 5.5 grs (below max) and 6.4 grs (above max). The 75% rule of thumb would have placed you at 4.8 grs, which in this example is shown to be very conservative.
Knowing this, with Bullseye I'd work in the 5.0 to 5.8 gr range with a 180 gr bullet - stop at 5.5 grs if you are the timid type. I understand that most shooters use lighter bullets, in which case this load is safe for them as well.
- you can safely use 40 S&W max loads, as it's a smaller case, and using the larger 400 CorBon case will lower pressures; and
- you must remain below 45 ACP max loads, as it's the same case, but the 400 CorBon has a smaller bore.
With a 180 gr as an example, for Bullseye (from the Alliant website), this puts you in a narrow band between 5.5 grs (below max) and 6.4 grs (above max). The 75% rule of thumb would have placed you at 4.8 grs, which in this example is shown to be very conservative.
Knowing this, with Bullseye I'd work in the 5.0 to 5.8 gr range with a 180 gr bullet - stop at 5.5 grs if you are the timid type. I understand that most shooters use lighter bullets, in which case this load is safe for them as well.
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