Math question

[feelinducky]

During my latest bout of insomnia I came of with a question. Probably of no significance but sometimes I geek out. I have a 270wsm I'm loading for. I want to switch bullets but the new bullet is shorter from the ogive to tip and longer from the base to the ogive. The new bullet will have more shank in the case. How much potential powder weight do I sacrifice from changing bullets? I would like to use RL 26. I need to figure out how much more base is in the case then figure out how much displacement that would be then figure out how much RL26 fits into that displacement. So far I have:
Bullet #1
OAL 1.3240
Base to Ogive .7650
bullet diameter .277

Bullet #2
OAL 1.3170
Base to Ogive .9210
bullet diameter .277

.9210-.7650=.1385

I now figure there is an additional +.156" of base into the case.
Volume of a cylinder: V=3.14(r2)(H)
3.14(.0192)2(.156)=.009405

What I don't know is the weight per volume of the powder??? Where can I find this?

I may be doing this wrong but I'm sure there are a few math geeks out there that can figure this out.

Thanks

 

[Edd]

Google Powder Density Chart

 

[Straight Shooter]

Are both bullets the same length?

Where did you get your radius?
V=3.14 x r squared x h
V=3.14 x (.0192 x .0192) x .156
V=3.14 x .00036864 x .156
V=.00018057461

 

[feelinducky]

No: OAL is overall length of bullet only, no case is in the measurement.

 

[cohunt]

Kinda hard to use a math equation since other things will affect the pressure

Bearing length, copper jacket alloy, lead core alloy hardness just yo name a few....I say step your load back 1 grain and work it back up

 

[Straight Shooter]

Plus you must remember that formula only works if the case was plumb full in the first place and there was no compression.

 

[feelinducky]

With 270wsm there no room left for the longer bullets. With the barnes ttsx and max charges it is compressed. So I think it is a legitimate question in theory.

 

[Mike 338]

The way I see it, it's less of a math problem and more of an experiment. When you enter in a new component, you just start over. Go from low to high all over again. More things than just volume/seating depth affects pressure and accuracy is pure voodoo. New load... start over.

 

[shaughn]

Google Alliant powders....go to site...proceed to Reloader 26 data page and see if they list your caliber and see if your bullet is listed...if not.. during business hours call Alliant powders and ask them if they have data for your bullet of choice or if some other bullet they do list is close enough....

Just glancing at data for 300 win mag reflects the following brands: Berger Sierra Speer Barnes Nosler Hornady....

Undiscovered country is not the place you want to explore...

 

[MagnumManiac]

I did this same very thing a long time ago when I was green in reloading, back then I would contemplate all the different bullets in the same weight and wonder exactly what you propose.
It was all a waste of time in fruition. Not a single bullet made diddly squat difference until I came across the 270gr Sierra in .375". It would force kernels between the boat tail and shoulder causing a bulge, those cases then could not chamber. The 375H&H is not alone in this, BUT generally speaking a bit more powder compression is neither here nor there.
Even my 270 Weatherby crunches powder when the correct burn rate is used with long bullets.

Cheers.

 

[LanceK]

If you have a lee reloading book, it lists cc's for it's loads to be used with the lee scoops, you could work backwards from there.

 

[Greyfox]

From one insomniac to another ...I personally wouldn't mess with the math. Once you figure the actual amount of bullet that extends into the case, compared to the original bullet, mark the bullet with the distance from the base. Stick it in some modeling clay, making an impression of the difference(like the spy's duplicate keys). Fill the impression with your powder, then weigh it in s scale for the difference....it's close enough and accounts for the air space between the powder granules.
IMO.

 

[feelinducky]

Like your idea Lance and Greyfox. My question was proposed out of curiosity to stimulate the brain.

 

[LanceK]

Like your idea Lance. My question was proposed out of curiosity to stimulate the brain.

I understand that completely.