115 gr .380- All things being equal


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71Commander
December 5, 2010, 09:10 AM
I recently loaded up and shot some 380's loaded up with 2.7 HP-38. OAL is .960. This load is in the Lee manual. Published velocity is around 775 fps. It's a sweet shooting round. Shot from a Kahr P380.

Question is am I just chasing squirrels?

Any estimates on the ft. lbs of energy with this round? The typical 90 gr 380 personal defense round is in the 200 ft. lb. range.

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71Commander
December 5, 2010, 09:26 AM
The mass of the 115 is greater than the 40 gr of the 22. That's gotta account for something.

The recoil of the 380 in almost nonexistent with the 115 gr bullets.

RidgwayCO
December 5, 2010, 12:21 PM
QuickLOAD predicts your load is producing 767 fps for 150 ft-lbs of energy. In the real world it's probably doing a little less. YMMV. Sounds like a good short-barrel penetrator, especially if it's comfortable out of the Kahr.

rfwobbly
December 5, 2010, 12:56 PM
If you've got a lot in front, Newton's 3rd law says that you are going to feel something at the rear.

Timer is telling you the truth. The converse is also true, if you don't feel any recoil (and yes, the slide spring is absorbing some of that energy) then you may have a bullet that gets deflected or stopped by clothing.

Sir Issac has been batting 1000 every year since 1687. I'd say the odds are not in your favor.

bds
December 5, 2010, 01:11 PM
Sir Issac has been batting 1000 every year since 1687. I'd say the odds are not in your favor.

Yup. From my physics class, F (force) = M (mass) x A (acceleration)

If you want to impart enough force on your target, you need not only mass, but also velocity. Reduction in terminal energy is the reason why I prefer the larger calibers like 40/45 for short barreled subcompacts. I figure there's enough of "Ooomph" left when the 165-200 gr bullets hit the target to get some attention. :D

Marlin 45 carbine
December 5, 2010, 03:16 PM
stick that .380 in the bg's belly button to avoid any 'deflection'.:eek:

AveryJ
December 11, 2010, 12:47 PM
Back to the top if your numbers on on the nose you have 266.897302 for a 90 grain at 775 and for a 115 at 775 you should be running 341.035442 foot pounds.

ssyoumans
December 11, 2010, 01:00 PM
Your energy numbers are way off.

A 90 gr at 775 fps is 120 ft-lbs
A 115 gr at 775 fps is 153 ft-lbs

AveryJ
December 11, 2010, 01:04 PM
I dont see how i used the regular formula for kinetic energy converted my units from grains to kilograms and then back to foot pounds from joules what formula did you use now i have to reavaluate all my handloads i was using ke=1/2mv^2

jbrown13
December 11, 2010, 01:39 PM
From what I can find, Muzzle Energy (ft-lb) can be calculated with the following formula:

The formula is:

(Bullet Weight) X (Muzzle Velocity) Squared / 450,411

This gives an answer of 153.353 ft-lb for a 115 grain bullet at 775 fps.

cheygriz
December 11, 2010, 01:51 PM
Why would you use such a big ol' cannonball in a .380??

71Commander
December 11, 2010, 03:11 PM
Why would you use such a big ol' cannonball in a .380??

Same reason I loaded up some 102 golden sabers in a 9mm. Got em close to 1400 fps with no signs of excessive pressure.

I had to test the round and see if it were close to 900 fps, which it isn't. It makes the 38 spl. slightly superior. Which is what I wanted to know.

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