diff --git a/core/src/net/sf/openrocket/rocketcomponent/ExternalComponent.java b/core/src/net/sf/openrocket/rocketcomponent/ExternalComponent.java
index acac70c8c..b81ee55b3 100644
--- a/core/src/net/sf/openrocket/rocketcomponent/ExternalComponent.java
+++ b/core/src/net/sf/openrocket/rocketcomponent/ExternalComponent.java
@@ -102,7 +102,7 @@ public abstract class ExternalComponent extends RocketComponent {
 	 */
 	@Override
 	public double getComponentMass() {
-		return material.getDensity() * getComponentVolume() * getInstanceCount();
+		return material.getDensity() * getComponentVolume();
 	}
 	
 	/**
diff --git a/core/src/net/sf/openrocket/rocketcomponent/LaunchLug.java b/core/src/net/sf/openrocket/rocketcomponent/LaunchLug.java
index 4b0c18912..0a436edc3 100644
--- a/core/src/net/sf/openrocket/rocketcomponent/LaunchLug.java
+++ b/core/src/net/sf/openrocket/rocketcomponent/LaunchLug.java
@@ -215,7 +215,7 @@ public class LaunchLug extends Tube implements AnglePositionable, BoxBounded, Li
 	
 	@Override
 	public double getComponentVolume() {
-		return length * Math.PI * (MathUtil.pow2(radius) - MathUtil.pow2(radius - thickness));
+		return length * Math.PI * (MathUtil.pow2(radius) - MathUtil.pow2(radius - thickness)) * getInstanceCount();
 	}
 	
 	@Override
diff --git a/core/src/net/sf/openrocket/rocketcomponent/RailButton.java b/core/src/net/sf/openrocket/rocketcomponent/RailButton.java
index 734966339..289b0842e 100644
--- a/core/src/net/sf/openrocket/rocketcomponent/RailButton.java
+++ b/core/src/net/sf/openrocket/rocketcomponent/RailButton.java
@@ -304,7 +304,8 @@ public class RailButton extends ExternalComponent implements AnglePositionable,
 		final double volInner = Math.PI*Math.pow( innerDiameter_m/2, 2)*getInnerHeight();
 		final double volStandoff = Math.PI*Math.pow( outerDiameter_m/2, 2)* baseHeight_m;
 		final double volScrew = 2f/3 * Math.PI * MathUtil.pow2(outerDiameter_m/2) * screwHeight_m;
-		return volOuter + volInner + volStandoff + volScrew;
+		final double volInstance = volOuter + volInner + volStandoff + volScrew;
+		return volInstance * getInstanceCount();
 	}
 	
 	@Override