Slow Burn / Long Pressure Curve Powder?

[Old Ironsights]

#1 Assuming a useable case capacity of 38-40gr water (aprox 2.5cc), case ID of .41 and a max pressure of 20,000 psi, what powder would y'all suggest to lob a 200gr .41 bullet to maximum velocity (20" barrel) ?

#2 Same scenerio, but max the pressure at 13,000.


I was looking at A2495BR or maybe BL-C(2)...???

[versifier]

That is a question for someone with a lot more experience in that direction than I have, but if it were my question, I would ask Felix or Maven on the CB board. Someone with the QuickLoad software could help, too, but alas, I do not own a copy.
There are probably some over here that could help you, too, and I'm sure we'll hear from them.

[Old Ironsights]

I was sent this link to a fun DOS program.


http://www.john-ross.net/suggestload.htm

Using SWAG data it says I should be using 24gr IMR 4227 to get some 1600+ fps at 15,000 cup or so out of a 200gr slug.

[versifier]

Interesting. A new toy to play with.

[Ranch Dog]

I've used the Suggest-A-Load program for years and it does a great job but it isn't capable of keeping up with or adding changes to a powder. I also rely on Load From A Disk but it won't work with these low pressure loads.

With SAL, remember it works with CUP rather than PSI so Old Ironsights request must be converted. An accepted formula for doing so is: . 20.0K PSI = 25.0K CUP and 13.0 PSI = 20.4 CUP.

I had to make a couple of assumptions with the input. I used 39.0-grains of H20 as the capacity, a cartridge length of 2", a bullet length of .5" and a cartridge OAL of 2.25". If you would provide these specifics, I would be happy to run it again.

It chooses H110.

[Old Ironsights]

The full case capacity of the 2.5" brass .410 case is roughly 6.03cc or 93.006gr water (my math may be off and I haven't done the SAL "water test"...) Minus 10gr for Head. (swag). I used a 24" barrel because that's what my 9410 has. (don't remember why I cited 20" up there.)

Cartridge length is 2.5" (flush-crimp load)

The bullet should have a rough OAL .5" - but I don't know that exactly yet. I'm basing that on the OAL of 2 stacked extant .410 90gr Fosters. (case on right is Rem .444 Marlin case)



SAL gives me the below for the way I calculated the data (for 25KCUP):



and this for 20KCUP



Whaddaya think?

[Old Ironsights]

I've used the Suggest-A-Load program for years and it does a great job but it isn't capable of keeping up with or adding changes to a powder. I also rely on Load From A Disk but it won't work with these low pressure loads.

With SAL, remember it works with CUP rather than PSI so Old Ironsights request must be converted. An accepted formula for doing so is: . 20.0K PSI = 25.0K CUP and 13.0 PSI = 20.4 CUP.

I had to make a couple of assumptions with the input. I used 39.0-grains of H20 as the capacity, a cartridge length of 2", a bullet length of .5" and a cartridge OAL of 2.25". If you would provide these specifics, I would be happy to run it again.

It chooses H110.

Thanks Ranch. What do you think of the assertion below?

I believe you must be using Denton Bramwell's linear fit for your CUP conversion? It isn't accurate below the 28,000 PSI low end of data Bramwell used because it doesn't intercept zero together with PSI. According to the Bramwell linear regression, 0 PSI = almost 12,000 CUP, which is obviously not possible.

I've done some power curve fitting that brings the two terms to zero simultaneously (and results in a higher R test number than Bramwell got). These find the conversion numbers will be closer to

13,000 PSI = 16,000 CUP
20,000 PSI = 22,500CUP

I ran the numbers using the above cup and came up with:

16,000 CUP



22,500 CUP



It gets more interesting every day... Less dense load, more velocity, less pressure. What's not to like?

[Ranch Dog]

It sounds good to me. The #1 project that SAAMI is working on is reestablishing every cartridge limit with PSI. This is and will take quite a while but in the near future CUP will be a thing of the past.