The AR-308 .308 Shim Kit by Primary Weapons is made of hardened steel and comes in silver finish, with a size of .837 and compatible with AR .308 and AR-15 rifles.

An archaic form of this washer was sold as a "pot mender", usually in small quantities through a retail ironmonger. This included two washers, a nut, and bolt, and a sealing washer of rubber, cork, or fibre sheet. They could be used for sealing small holes, rust spots or removed pipe connections in water tanks or large cooking vessels. a b "Fastener Design Manual" (PDF). NASA. 1990. pp.9–10. Archived from the original (PDF) on 15 May 2010. Fasteners, such as screws, nuts, and bolts, hold these pieces together. But these fasteners can sometimes put too much pressure on the object they are fastening. Phosphating – A resilient, but abrasive surface is achieved by incorporating a zinc-phosphate layer and corrosion-protective oil. Anyway, the theory is that as a filter of this type gets used, more & more of the holes trap particles of dirt and thus more of the larger holes get partially or fully filled. If you graphed this out over time you would see that the flow starts to become more restricted but the average particle sizes getting through also reduces.Each washer is good for close to 1 1/2 turns for just-right timing, and is patented under US Patent Number 100,041,753. These washers auto-center and are good for close to 1 1/2 turns for just-right timing, eliminating the struggle of traditional crush washers. The S.I. crush washers are great for replacing your used ones and for installing a new muzzle device onto your AR. These high-quality components will provide excellent fit and reliable function in your AR series rifle. Installing crush washers is simple, but attention to detail is critical. The surfaces that the crush washer will be installed between should be clean and free from debris, rust, and other contaminants that may compromise the integrity of the seal. The crush washer should be inserted by hand, and its edges should line up with the fasteners and not go over them. Advantages of using Crush Washers

They are preferred over similar, more expensive, heavier, and larger springs that take up more space. As a result, they’re ideal for applications requiring some level of adaptability. As a result, spring washers are common in actuators on airplanes, including flight controls and landing gear. Countersunk washers : Countersunk washers make installing flat or oval head countersunk screws flush with the part surface. They’re commonly found in consumer products like cabinets and furniture. Tab washers : Tab washers have a single tab or several tabs and notches that contour to fit around bolts and nuts. Sometimes, they lie flat. Tab washers are perfect for difficult areas, as they can withstand high temperatures and vibrations. Rivets : Rivets are permanent fasteners having a head, shank, and tail. You can’t disassemble them without damaging the joints. Riveting is the process of applying force to two materials to join them together, manually or using a machine.

Type and form [ edit ] A plain washer and a spring washer are placed on a bolt between the nut (on the threaded end) and the bolt head.