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Alternative Timber Species for Rifle Butt

M. A. Sattar
Director (Ex.)
Seasoning and Timber Physics Division, Bangladesh Forest Research Institute, Chittagong.

Abstract/ Executive Summary:

A collaborative study was undertaken to find out suitable indigenous timber species alternative to Walnut for manufacture of rifle butt. Various properties like, anatomical, physical, mechanical, machining, treating and finishing, of five potential species were studied and compared with those of Walnut. A time- dependant kiln schedule was developed for seasoning the alternative species in a single charge. The assembled rifle butts of all these species were subjected to the standard service and endurance tests. The results indicate that Gamar, light colored Champa and Teak may be used along with Chickrassy for manufacture of rifle butt.

Keywords: Indigenous timber species, Walnut, Rifle butt, Kiln schedule, Seasoning.

Location:

Start Date: 00-00-0000

End Date: 00-00-0000

Program Area: Variety and Species

Commodity: Timber

Objectives:

To find the suitability of alternative indigenous species for rifle butt

Methodology:

Five indigenous species, Chickrassi (Chukrassia velutina), Champa (Michelia champaca), Chapalish (Artocarpus Chaplasha), Gamar (Gmelina arborea) and Teak (Tectona grandis) were selected primarily on the basis of availability and desirable properties. Logs of these species were procured in green condition from chittagong Hill Forests. Fifteen planks of 5.6 cm ´ 20.8 cm ´ 91.5 cm were prepared from logs of each species. A set of standard specimens were also prepared from these logs for studying different properties.Anatomical features like colour, grain and texture were noted for wood of each species. Density values were determined based on air dry volume and oven dry weight. Shrinkages in the tangential and radial directions were calculated by drying wooden specimens in a conditioning chamber from green condition to14% moisture content. Relevant mechanical properties were determined from a separate set of specimens in accordance with ASTM specifications (1971).Wooden blanks, 5.6 cm ´ 20.8 cm ´ 91.5 cm, were dried in a conventional steam-heated force draft seasoning kiln. Blanks of all the five species were dried in a single charge from the green condition to about 14% moisture content, taking care against any objectionable drying degrade. A kiln schedule dependent upon time was developed. In this drying charge, Gamar blanks were stacked in the bottom layer, and Champa, Chickrassy, Teak and Chapalish were placed in successive upper layers. This stacking method facilitated the unloading and removal of seasoned timber of the particular species at the appropriate stage of drying. At the conclusion of drying, defect free blanks were selected and these were sent to IAE for further study at BOF.

Rifle butts were manufactured with the help of a set of special type of wood working machines. The machines included vertical copy milling, copy turning, horizontal milling and sanding. After proper sanding. the manufactured butts were soaked in a linseed oil bath for about 1¹/₂ hour at a temperature of 65 to 75⁰C.These were then left in a metal tray for 24 to 48 hours to allow them to dry. The butts were again sanded to remove any excess linseed oil on the surfaces. These were finally polished with shellac and spirit for making them ready for use as finished butts.Five butts of each of the selected species were assembled with semi-automatic Chinese type rifles. For service test, these were sent to the infantry unit of Bangladesh Army for extensive use for one year during the training period. The test included firing, handling, carrying, rough use, field stripping, etc.

One butt of each species was subjected to the endurance test following the standard procedures. For this, the rifle was mounted on a firing stand and firing of 30-40 rounds per minute was done continuously. The rifle was cooled down by placing it in a cold water bath for 3 to 4 minutes after every 100 rounds of firing. The butts showed no failure even on initial 1000 rounds followed by 500 additional rounds of firing.

Source of Information: Bano biggyan patrika, Vol :15 (1 & 2), Jan-July 1986, 3-10

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

All the alternative timber species can be seasoned efficiently in a single charge of a seasoning kiln. For this a time-dependant kiln schedule developed at FRI can be conveniently employed.Gammar was found to be the best alternative species for manufacturing rifle butt. It was found to possess properties similar to Walnut and superior to the conventional alternative species, Chickrassy, now in use.Light colored Champa was the next best alternative species. It conformed to all the properties required for manufacture of rifle butt.Chickrassy was observed to be third in rank in respect of suitability for rifle butt.Teak was also found to be a suitable alternative species.

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