WorldWide Drilling Resource

29 WorldWide Drilling Resource ® JANUARY 2016 Plywood vs. Hardwood Adapted from Information by the Bureau of Alcohol, Tobacco, Firearms, and Explosives The U.S. Department of Justice’s Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) has received numerous inquiries regarding substituting plywood for hardwood in type 1 and type 2 magazines. Plywood is manufactured from sheets of wood glued or cemented together with the grains of adjacent layers rotated up to 90 degrees from one another. Although some ply- wood is comprised of hardwood, plywood made from hardwood is not considered hard- wood for ATF magazine construction (or bullet-resistance) purposes. ATF Ruling 76-18, based upon the Institute of Makers of Explosives’ Safety Library Publication No. 1 (IME SLP-1), Construction Guide for Storage Magazines, addresses alternate construction to meet bullet-resistance requirements in type 1 and type 2 magazines. The ruling specifies several different types of alternate bullet-resistant construction including the use of plywood. For example, under the 1976 ruling, 1⁄8-inch steel lined with an interior of 5 inches of hardwood; and 1⁄8-inch steel lined with an intermediate layer of 4 inches of hardwood and an interior lining of 3⁄4-inch plywood both meet the bullet-resistance standard. This combination may suggest plywood provides greater bullet resistance than hard- wood, however, the ruling also allows for a construction of 3⁄16-inch steel lined with 4 inches of hardwood; and 3⁄16-inch steel lined with 6-3/4 inches of plywood. This comparison seems to indicate a greater thickness of plywood is necessary to equal a certain amount of hardwood. Part of the reason for this apparent inconsistency is the IME SLP-1 was not intended to specify ratios of one material to another for magazine construction. The IME SLP-1 specifies multilayered construction made of common materials, used in varying thicknesses, which passed IME bullet-resistance testing. There is no one-to-one correlation between plywood and hardwood, nor is there a “ratio” for one material to another which could be used universally for explosives magazine construction. The use of plywood in type 1 and type 2 magazine construction must comply with ATF Ruling 76-18. A variance is required to use plywood thicknesses which do not conform to this ruling. '6(- ( '10= 0'>' 38*0 *003,, 6*2' '880* 6**/ 36 136* .2+361'8.32 ('00 36 :.7.8 97 320.2* 1.(-.,'2,6392);'8*6 (31 #-967)'= !*,.786'8.32 4*27 ? 3'6) 3+ .6*(8367@ **8.2, ? $4)'8* ? # $4)'8* ? ( 00-.2*= *(896* ? 9<.0.'6= 98.2, ? 3(/8'.07 ? '259*8 9<.0.'6= "(-30'67-.4 9(8.32 ? '7.23 .,-8 6.)'= !*,.786'8.32 4*27 ? & 229'0 **8.2, ? 9<.0.'6= 92(-*32 ? #6')* "-3; 0336 4*27 ? %*2)36 *137 8- 229'0 32:*28.32 &% ! "" * "(%$ ))) (" $( ' & $ %# # " (" $( $ ( " !" !! ! &% ! % ! (" $( & $ $ $ " ! $ $ ! ! $ ! $ # $ $ $