[Beladran]

OK so i have been reading this book and so far it makes me feel stupid, like why didnt i think of that or yea that makes since now...
any way there is a section in there dealing with effciency of a load.

as a general rule of thumb when dealing with powders that potential energy per grain is not known you can use 200 ft/lbs per gr.

From a military manual asserts the 30 cal M-2 Ball contains 50 gr of powder and has a muzzle velocity of 2800fps and a muzzle energy of 2643t/lbs. If you multiply 50gr times the pow potential of 178ft/lbs this cartridge has the ability to put out 8900ft/lbs of energy. Efficiency of the round is only 29.7%

one way they said to improve efficiency is is to play with the shoulder angle which is why akleys, jdj, weatherbys, short mags, etc etc are more efficient than their parrent cases.

 

[mascott]

wow beladran, you are getting really deep into this. this is both good and interesting to the reloading community. It's nice to know we have such avid shooter's and gun lover's to continue on our mission. We must protect and defend our 2nd amendment rights at ALL costs. If these fail, we have truly lost our nation. OK I'm stepping down off the podium now. :OT1:

 

[Beladran]

well i guess its the engineer in me that wants to know why "this" works and "that" dont, or why you get more fps from this and not that. I like to ask "why". Did you know bullets shot on the equater drop less than bullets fired further north or south because of centripical force? lol this book is deep yal need to read it

 

[X-Ring]

Sounds interesting, What book is it?

 

[Will_M]

centripical force

Centripetal force

 

[SubGunFan]

.......................... Did you know bullets shot on the equater drop less than bullets fired further north or south because of centripical force? ........................

First, I am NOT saying you are wrong. Just as an Engineer (Structural, not Mechanical) also, I am not agreeing........ yet. While the angular velocity at the different latitudes are the same, the radius is greatest at the equator. DUH ! ! ! Wait a minute here "stupid me". Centripetal force is greatest at the Equator which works AGAINST gravity. Gravity is a constant force (equal all over the globe). So YES, I now agree with you.

My head now hurts.... It is time for bed.



.

 

[captain-03]

Darn - Ya'll all TOO Smart for me!!!!!! :thinking:

 

[Beladran]

the book is "understanding firearm ballistics" by robert a rinker

 

[Beladran]

lol ok i will leave you one more to think about
a projectile will deviate 6" to the right at 1000 yards from the earths rotation(northern hemi). Maximum drift occurs when the bullet is fired toward the southeast and minimum drift when fired to the northwest. This is in addition to the normal gyroscopic spindrift in the direction of the rifling twist

 

[nonnieselman]

lol ok i will leave you one more to think about
a projectile will deviate 6" to the right at 1000 yards from the earths rotation(northern hemi). Maximum drift occurs when the bullet is fired toward the southeast and minimum drift when fired to the northwest. This is in addition to the normal gyroscopic spindrift in the direction of the rifling twist

There is a bazillon page thread on this over on snipershide.. :lol4:

 

[bigsig]

"well i guess its the engineer in me"
How did you get an engineer in you? I don't want to know.
Dude, you have to watch how you word things with people like me around.

 

[Beladran]

well they have these little gnomes and one of them needed a place to hide and ugh well.... lol

 

[nonnieselman]

how about a 210gr .308 at 2850fps with 71grs powder?

 

[3spop]

what if it's left handed twist?

 

[SubGunFan]

how about a 210gr .308 at 2850fps with 71grs powder?

That sounds like a BOMB to me........................

.

 

[nonnieselman]

how about a 210gr .308 at 2850fps with 71grs powder?

That sounds like a BOMB to me........................

.

woops.... 2750fps, had to look back at my notes.
i love my 300wm :gun:

Shot steel plates this weekend out at 600yds and it makes them swing a lil compared to the 308..

 

[Limbic]

I've got the same book. Super involved and has some good tips and facts. 1st law is energy can neither be destroyed or created. The most efficient round is roughly 50%. 50-60% of the energy is lost in heat and such. Sections on recoil and ballistics are even better.