Barrier penetration: Bi-Metal FMJ vs Copper FMJ.

[Pyro]

Would a steel core, bi-metal jacket bullet such as from Tulammo penetrate barriers better than a lead core, copper jacketed FMJ?

Edit (since I can hear it coming already): You are correct to inform me that Tulammo uses soft steel and should not be regarded as 'armor piercing' bullets. My question stands, will it still penetrate barriers better than a lead-core bullet?

 

[firesky101]

worth a shot to try it, but i gotta doubt it.

 

[481]

Would a steel core, bi-metal jacket bullet such as from Tulammo penetrate barriers better than a lead core, copper jacketed FMJ?

I doubt it. The steel typically used in such jackets is very thin and has mechanical properties that are no greater than the 95Cu/Zn5 gilding metal that is used to make bullet jackets.

Gilding metal has an ultmate tensile strength of 290 MPa http://matweb.com/search/DataSheet.aspx?MatGUID=b19ba57dfef44f4ebb65ed0c28ef7237 and the low-quality low carbon mild steel that is used for bullet jackets can have a UTS as low as 250 MPa. http://matweb.com/search/DataSheet.aspx?MatGUID=034970339dd14349a8297d2c83134649

I doubt that there is much difference between the two.

Edit (since I can hear it coming already): You are correct to inform me that Tulammo uses soft steel and should not be regarded as 'armor piercing' bullets. My question stands, will it still penetrate barriers better than a lead-core bullet?

You do know that both steel jacketed and gilding metal jacketed bullets have lead cores?

 

[Pyro]

You do know that both steel jacketed and gilding metal jacketed bullets have lead cores?

I was told they used a steel core as well.

 

[481]

Pyro,

I found this here on THR not too long ago-

9mm GECO 124 gr. FMJ- Swiss RUAG
__________________

Results

Jacket weight: 18.32 grains (14.8%)
Core weight: 105.422 grains (85.2%)
Total: 123.742 grains

Jacket
4.83% Cu (plating)
94.6% Fe
0.63% traces of Zn, Pb, Bi, Ni, Cr, Al

Core
98.65% Pb
1.3% Cu
< 0.05% Al, Fe, Bi, Zn

All of the bimetallic jacket ammo I've seen uses a lead core. Steel lacks the density (7.85 g/cc for steel vs. 11.33 g/cc for lead) necessary to make the weight while remaining compact enough to fit.

Even the heavily steel jacketed Swedish 9mm AP round (the M/39b) has a core made of lead.

Do you have any examples of such ammo (steel jacket and steel core- no lead) ?

 

[Pyro]

I should find some 2x4 and test it out since that seems to be the only reason to get an answer. I wonder which jacket will deform less.

 

[The_Armed_Therapist]

The range at which I shoot has some of those metal silhouettes. The guy who owns the place does not allow anyone to shoot Tulammo at them. According to him, they pierce the metal silhouettes whereas the FMJ rounds do not. This is what the guy told me.

 

[rcmodel]

I was told they used a steel core as well.

No, it isn't, or it could not be imported into the USA.
That would violate Federal Law.

AP handgun ammo was outlawed by the 1994 Crime Control Act.

The definition of AP ammo is at 18 USC sec. 921(a)(17):
"(B) The term `armor piercing ammunition' means-

(i) a projectile or projectile core which may be used in a handgun and
which is constructed entirely (excluding the presence of traces of other
substances) from one or a combination of tungsten alloys, steel, iron, brass,
bronze, beryllium copper, or depleted uranium; or

(ii) a full jacketed projectile larger than .22 caliber designed and
intended for use in a handgun and whose jacket has a weight of more than 25
percent of the total weight of the projectile.

ATF has listed the following rounds as AP ammo:
All KTW, ARCANE, and THV ammo.
Czech made 9mm Para. with steel core.
German made 9mm Para. with steel core.
MSC .25 ACP with brass bullet.
BLACK STEEL armor and metal piercing ammunition.
7.62mm NATO AP and SLAP.
PMC ULTRAMAG with brass bullet (but not copper).
OMNISHOCK .38 Special with steel core.
7.62x39 ammo with steel core bullets.

ATF has specifically exempted the following rounds:
5.56 SS109 and M855 NATO rounds, with a steel penetrator tip.
.30-06 M2 AP ammo.

rc