My choice of weapon is Vallejo paints, thought this conversion chart might be useful to people, you can find it on the
Vallejo website
For quick reference here's the more common paints used, Tamiya, Humbrol and Revell, the full PDF can be found
here Tamiya 
Revell 
Humbrol 
Code:
# Colour # Colour
400 Plastic Putty 887 Brown Violet
470 Glossy Medium 888 Olive Grey
510 Glossy Varnish 889 US Olive Drab
520 Matte Varnish 890 Reflective Green
521 Metal Medium 891 Intermediate Green
522 Satin Varnish 892 Yellow Olive
523 Liquid Mask 893 US Dark Green
524 Thinner 894 Russian Green
540 Matte Medium 895 Gunship Green
596 Glaze Medium 896 German Extra Dark Green
597 Drying Retarder 897 Bronze Green
598 Crackel Medium 898 Dark Sea Blue
730 Yellow Fluorescent 899 Dark Prussian Blue
733 Orange Fluo 900 French Mirage Blue
735 Magenta Fluo 901 Pastel Blue
736 Blue Fluo 902 Azure
737 Green Fluo 903 Intermediate Blue
790 Silver 904 Dark Blue Grey
791 Gold 905 Blue Grey Pale
792 Old Gold 906 Pale Blue
793 Rich Gold 907 Pale Greyblue
794 Red Gold 908 Carmine Red
795 Green Gold 909 Vermillion
796 White Gold 910 Orange Red
797 Copper 911 Light Orange
800 Gunmetal Blue 912 Tan Yellow
801 Brass 913 Yellow Ochre
802 Red Sunset 914 Green Ochre
803 Brown Rose 915 Deep Yellow
804 Red Beige 916 Sand Yellow
805 German Orange 917 Beige
806 German Yellow 918 Ivory
807 Oxford Blue 919 Foundation White
808 Blue Green 920 German Uniform
809 Royal Blue 921 English Uniform
810 Royal Purple 922 US Uniform
811 Violet Blue 923 Japanese Uniform WWII
812 Violet Red 924 Russian Uniform WWII
814 Cadm. Umber Red 925 Blue
815 Flesh Tone 926 Red
816 Luftwaffe Uniform WWII 927 Dark Flesh
817 Scarlet 928 Light Flesh
818 Red Cuir 929 Light Brown
819 Iraqui Sand 930 Dark Blue
820 Offwhite 934 Transparent Red
821 German Cam Beige WWII 935 Transparent Orange
822 German Cam Black Brown 936 Transparent Green
823 Luftwaffe Cam 937 Transparent Yellow
824 German Cam Orange Ochre 938 Transparent Blue
825 German Cam Pale Brown 939 Transparent Smoke
826 German Cam Medium Brown 940 Saddle Brown
827 Lime Green 941 Burnt Umber
828 Woodgrain 942 Light Green
829 Amaranthe Red 943 Grey Blue
830 German Fieldgrey WWII 944 Old Rose
831 Tan Glaze 945 Magenta
832 Verdigris Glaze 946 Dark Red
833 German Cam Bright Green 947 Red
834 Natural Wood 948 Golden Yellow
835 Salmon Rose 949 Light Yellow
836 London Grey 950 Matt Black
837 Sand Light 951 White
838 Emerald 952 Lemon Yellow
839 Ultramarine Blue 953 Flat Yellow
840 Light Turquoise 954 Yellow Green
841 Andrea Blue 955 Flat Flesh
842 Gloss White 956 Clear Orange
843 Cork Brown 957 Flat Red
844 Deep Sky Blue 958 Pink
845 Sunny Skintone 959 Purple
846 Mahogany Brown 960 Violet
847 Dark Sand 961 Sky Blue
848 Super Silver 962 Flat Blue
849 Super Gold 963 Medium Blue
850 Medium Olive 964 Field Blue
851 Deep Orange 965 Prussian Blue
853 White Glaze 966 Turquoise
854 Brown Glaze 967 Olive Green
855 Black Glaze 968 Flat Green
856 Ochre Marron 969 Park Green Flat
857 Golden Olive 970 Deep Green
858 Ice Yellow 971 Green Grey
859 Black Red 972 Light Green Blue
860 Medium Fleshtone 973 Light Sea Grey
861 Glossy Black 974 Green Sky
862 Black Grey 975 Military Green
863 Gunmetal Grey 976 Buff
864 Natural Steel 977 Desert Yellow
865 Oily Steel 978 Dark Yellow
866 Grey Green 979 German Cam Dark Green
867 Dark Bluegrey 980 Black Green
868 Dark Seagreen 981 Orange Brown
869 Basalt Grey 982 Cavalry Brown
870 Medium Sea Grey 983 Flat Earth
871 Leather Brown 984 Flat Brown
872 Chocolate Brown 985 Hull Red
873 US Field Drab 986 Deck Tan
874 US Tan-earth 987 Medium Grey
875 Beige Brown 988 Khaki
876 Brown Sand 989 Sky Grey
877 Gold Brown 990 Light Grey
878 Old Gold 991 Dark Sea Grey
879 Green-brown 992 Neutral Grey
880 Khaki Grey 993 White Grey
881 Yellow green 994 Dark Grey
882 Middlestone 995 German Grey
883 Silvergrey 996 Metallic Gold
884 Stone Grey 997 Metallic Silver
885 Pastel Green 998 Metallic Bronze
886 Green Grey 999 Metallic Copper
Linear Mode
