9mm ammo questions ( 147gr in 380 )
James D. Del Vecchio
#On a side note, if I were to reload a .380 using a 147gr. bullet, wouldn't I
#get the same effect as a sub-sonic cartridge for 9mm Parabellum? Intuitively,
#this should work, but has anyone actually tried it?
--------------------
A standard load for the 380 is 95 grains at 955 fps for 190 fp of energy.
Assuming the same amount of powder, the I think the result would be 147 grs
at about 617 fps for 124 fp of energy. This load would be slower than even
the measly .25 ACP is at 100 yards, and have less muzzle energy than the
32 auto.
You could load it hotter, but only by so much: the 380 is blowback action
rather than short recoil like the 9mm, and can only fire rounds of limited
energy.
An even better question, is how hot can you safely load your 380 using
normal 95 grain bullets? This I would like to know.
Jim Del Vecchio
John Bercovitz
#mihara%cory.Ber...@ucbvax.Berkeley.EDU (Mark Mihara) writes:
#
##On a side note, if I were to reload a .380 using a 147gr. bullet, wouldn't I
##get the same effect as a sub-sonic cartridge for 9mm Parabellum? Intuitively,
##this should work, but has anyone actually tried it?
# --------------------
# A standard load for the 380 is 95 grains at 955 fps for 190 fp of energy.
#Assuming the same amount of powder, I think the result would be 147 grs
#at about 617 fps for 124 fp of energy. This load would be slower than even
#the measly .25 ACP is at 100 yards, and have less muzzle energy than the
#32 auto.
# You could load it hotter, but only by so much: the 380 is a blowback action
#rather than short recoil like the 9mm, and can only fire rounds of limited
#energy.
# An even better question, is how hot can you safely load your 380 using
#normal 95 grain bullets? This I would like to know.
As I showed in my deadly-boring series of epistles on government model
dynamics of a few months ago and again mentioned in my deadly-boring
epistle of a few weeks ago on government model internal ballistics,
slide movement to the rear is proportional to bullet movement toward
the front in the ratio of the masses of the bullet and slide. One might
think of the bullet and slide as two weights at the pivot point of a seesaw.
To maintain the balance when the bullet is moved, the slide must move in the
opposite direction a smaller amount according to the ratio of masses.
(This statement must be modified slightly to account for the friction of
the case walls against the chamber walls.)
The implication here is that if you use a bullet which is 50% heavier, the
slide will have moved 50% farther by the time the pressure peaks (if the
pressure peaks at approximately the same bullet position for either load).
Since a blowback firearm depends on the cartridge case's walls to some
extent to hold in the pressure, and the walls get thinner as you move toward
the case mouth, the heavier bullet is going to cause the thinner part to
be stressed more and perhaps blow out.
I think the inference to be drawn here is that the heavier-bullet load will
have to operate at a lower pressure than the light-bullet load to avoid case
blowout. If the bullet is very much heavier, an extremely weak section of the
case will be exposed making maximum pressure so low as to make the load
impractical.
JHBer...@lbl.gov (John Bercovitz)