This science fair project aims to find out how the velocity of the bullets is affected by coating them with dry lubricants. The tests will be carried out using a rifle and bullets coated with molybdenum sulfide (moly).
Moly-coated bullets will travel faster than ordinary bullets?
Molybdenum Sulfide (Moly) coated bullets
Bullets have along been coated with dry lubricants in order to improve their velocity. In particular the availability of of such ready-coated bullets has increased their popularity. There are 3 types of coating typically used on bullets, namely Molybdenum disulfide (Moly), Hexagonal Boron Nitride and Tungsten disulfide. Moly is the most common type of bullet coating used in firearms However moly can cause erosion of the gun’s barrel because it reacts with moisture to produce harmful substances.
Lubricants, Molybdenum sulfide, Hexagonal Boron Nitride, Tungsten disulfide, friction, pressure, velocity
The materials required for this science fair project are:
- 1 rifle
- 10 non lubricant-coated rifle bullets
- 10 moly-coated rifle bullets
- 1 trained, qualified adult to handle the rifle
- shooting ear muffs
- 1 chronograph to measure bullet velocity
- 1 rifle stand
- Firing range
1. The independent variable of this science fair project is the coating on the bullet – moly coated and non-coated bullets . The dependent variable is the speed of the bullet. This is measured using a chronograph. The constants (control variables) are the type of the rifle, the weight of the bullet and the sensitivity of the chronograph.
2. Set up the rifle on the rifle stand, 3 meters away from the chronograph. Load the rifle with the bullets that are non coated. Fire ten shots using the non coated bullets. Measure the velocity of the bullets using the chronograph. Record the measurements in the table provided below. Obtain the average velocity of the non coated bullets from the 10 shots.
3. The procedure 2 is repeated using the 10 moly-coated bullets. The speeds are again measured using the chronograph and the velocities are recorded in the table below. The average speed for the moly-coated bullets is also calculated.
The non-coated bullets travel at a higher velocity compared to the moly-coated bullets.
||Bullet velocity measured with chronograph (feet per seconds)
The hypothesis that the moly-coated bullet travels faster than a bullet that is not coated with lubricant is not proven correct.
Coating the bullets with dry lubricants such as Molybdenum disulfide (Moly) will help to reduce the friction and heat generated inside the barrel of the gun. This will also increase the lifespan of the barrel and reduce the need for frequent cleaning of the gun.
However, lubricant coated bullets result in lower barrel pressure. This lower pressure will result in the lubricant coated bullet to travel at a lower velocity compared to bullet without coating. In order to increase the velocity of lubricant-coated bullets, additional powder needs to be added in the case provided that there is enough space in it. If sufficient gun powder is loaded into the case to produce the same pressure as the bullet without the coating, the moly-coated bullet will actually travel at a much higher velocity than the non-coated bullet.
The science fair project can be repeated with different types of lubricants.
Guide to bullet coating - http://www.6mmbr.com/bulletcoating.html
Shooting chrony chronograph - http://www.eabco.com/chronyshooting.htm
.22 long rifle - http://en.wikipedia.org/wiki/.22_Long_Rifle#cite_note-TimesNews_2008-03-28-1