Bullet Weight Loss on Firing

A test was conducted to determine the weight loss of some bullets after discharge. Results are given in Table 20.3. From the limited experimental data it would appear that, as expected, the full metal jacketed bullets lose less than the soft unjacketed bullets. The FMJ bullet with its base enclosed lost less than its equivalent with its base exposed. This is also predictable as the exposed base is subject to erosion during discharge. The .38 SPL + P unjacketed bullet

Table 20.1 Particles on New Ammunition

Ammunition Pb Only Sb Only Pb, Sb Brass

Observations

GECO 9 mm Large Luger. number

Brassjacketed bullet

None

GECO .32 S&W long. Unjacketed Pb bullet

Large number

None

Very Small small number number

Unjacketed Pb bullet

None

Very Large small number number

None Large All the brass particles were number irregular shaped whereas the Pb-only particles were a mixture of irregular and spherical. The Pb-only particles contained some or all of Al, Ca, Cl, Cu, S, Si, Ti, Zn at minor or trace level.

A few Fe particles were present. Unusual particles detected were Bi, P, Al major, Si minor, Ca, Fe trace; Cr, Fe major, Si, Zn trace; Zn major, Fe, Cu minor, Si trace; Si, Al, Fe major, Ca minor, Mn, Zn trace.

All the brass particles were irregularly shaped whereas the Pb-only particles were a mixture of irregular and spherical. The Pb-only particles contained some or all of Al, Ca, Cl, Cu, S, Si at minor or trace level. The few Pb, Sb particles were spherical. Unusual particles detected were Fe, Cr major, Ni minor, Mn trace; Ti major, Fe, Si minor, Al trace.

None Numerous Pb, Sb particles and a few Sb only were detected. No other particle types were detected. The particles were mainly spherical. All particles contained Sn and Ti at minor or trace levels in addition to Ca, Cu, Fe, S, Si at minor or trace level.

Table 20.1 Particles on New Ammunition (Continued)

Ammunition Pb Only Sb Only Pb, Sb Brass Observations

GECO .38 Special. Unjacketed Pb bullet

Large number

None

Unjacketed Pb bullet

None

None

LAPUA 9 mm Luger. Cu Jacketed bullet

Small Very number small number

None None Numerous Pb-only particles and a few Fe particles detected. No other particle types detected. The particles were a mixture of irregular and spherical shapes. All the Pb-only particles contained Sn and Ti at minor or trace level in addition to S, Si.

None None None of the particles contained Pb, Sb, or Ba. A large number of predominantly irregular particles were detected containing some or all of the following: Al, Ca, K, Fe, Si, Ti at major, minor or trace level, Cr, Mg at minor or trace level, Cl, Cu at trace level.

Small Very All the brass particles were number small irregular whereas the Pb number only, Sb only, and Pb, Sb particles were all spherical. There were numerous particles containing some or all of the following: Al, Ca, Cl, Cr, Fe, Mg at major, minor or trace level, K, Ni at minor or trace level, Cu, Ti at trace level. Unusual particles detected were Fe, P, Si major, Ca minor, Cl, Cu trace; Fe, Cr, Cl major, Si trace.

Table 20.1 Particles on New Ammunition (Continued)

Ammunition

Pb Only

Sb Only

Pb, Sb

Brass

Observations

LAPUA .38

Large

None

Very

Large

All the brass particles were

SPL.

number

small

number

irregular whereas the Pb-

Unjacketed

number

only particles were a

Pb bullet

mixture of irregular and spherical. The Pb, Sb particles were spherical. Several Fe particles were detected. Unusual particles detected were Zn major, S, Si minor, Ca, Cr, Fe, trace; Cr, Fe major, Si minor, S trace.

LAPUA .357

Very

None

Large

Very

All the brass particles were

MAG.

small

number

small

irregular as were the Pb-

Brass case

number

number

only particles. The Pb, Sb

and primer

particles were a mixture of

cup

irregular and spherical and

Half Cu

accompanying elements

jacket, Pb

were Ca, Cu, S, Si at minor

H.P bullet

or trace level.

Note: See Glossary for firearms/ammunition-related abbreviations.

Note: See Glossary for firearms/ammunition-related abbreviations.

showed a marked increase in loss. Again, this is predictable as the bullet travels at a considerably higher velocity (pressure) than the .380 revolver bullet and is consequently subjected to greater stress. Barrel length and rate of rifling twist may be among other contributing factors. The three sources of weight loss are erosion of the base by the hot propellant gases, engraving of the outside surface by the rifling of the barrel, and friction. It has been noted in casework that fired bullets with exposed bases frequently have powdered lead at the base area. Also noted on some occasions are embedded propellant granules or indentations caused by the granules, in the base of the bullet.

Although the weight loss may appear to be insignificant in terms of the total weight of the bullet, it is not insignificant in terms of its potential to

Table 20.2 Particles on Unloaded Ammunition

Pb, Sb,

Ba, Ca,

Pb

Sb

Ba

Ammunition

Ba

Sb, Ba

Si

Pb, Ba

Pb, Sb

Only

Only

Only

GECO 9 mm

37

1

None

6

24

>100

10

None

Luger

GECO .38

18

2

2

1

>100

>100

3

1

S&W

Note: See Glossary for firearms/ammunition-related abbreviations.

Note: See Glossary for firearms/ammunition-related abbreviations.

Table 20.3 Bullet Weight Loss on Firing

Weight

Weight

Range

Range

Weight

Weight

Average

Average

Before

After

Loss

Loss

Weight

Weight

Bullet Type

Firing (g)

Firing (g)

Range (g)

Range (%)

Loss (g)

Loss (%)

9 mm P

7.4322

7.4206

0.0111

0.1485

0.0119

0.1592

Blazer FMJ

(base

7.4741

7.4630

0.0125

0.1678

enclosed)

9 mm P RG

7.5166

7.4951

0.0176

0.2316

0.0224

0.2942

FMJ (base

exposed)

7.6288

7.6033

0.0284

0.3770

.380 REV R.P

9.3935

9.3535

0.0271

0.2862

0.0364

0.3850

Unjacketed

Pb

9.5412

9.4936

0.0476

0.4989

W-SUPER-W

10.2137

10.1214

0.0625

0.6104

0.0840

0.8490

.38 SPL +P

Unjacketed

10.2679

10.1962

0.1051

1.0277

Pb

Note: See Glossary for firearms/ammunition-related abbreviations.

Note: See Glossary for firearms/ammunition-related abbreviations.

produce a large number of discharge residue particles originating from the bullet. This work supports the proposition that the bullet makes a contribution to the discharge particle population.

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