Hex lock nuts, nylon insert GRADE8 1/2″ x 13 zinc yellow
The nylon on these get looser with repeated loosening / tightening cycles so buy a few extra.
Grade 8 Bolt info
GRADE 8 CARRIAGE BOLTS:
Grade 8 carriage bolts are a crucial component for withstanding the immense stress forces generated when high-energy rifle rounds hit plates. These bolts have a high tensile strength of 150,000 psi, surpassing the 60,000 psi of low carbon non-grade bolts commonly found in hardware stores. While grade 8 bolts are not bulletproof and can still be penetrated, they are designed to endure hits more effectively than non-grade bolts.
One notable advantage of using carriage bolts is their low-profile heads, which significantly reduce splatter deflection. Additionally, when paired with square hole plates, carriage bolts eliminate the need for using two wrenches during installation, providing convenience and saving time.
It is important to note that grade 8 carriage bolts may not be readily available at local hardware stores, so it’s advisable to purchase them along with your order to ensure you have the appropriate hardware for your shooting targets.
Target failures can be frustrating, but using grade 8 bolts can greatly reduce the likelihood of such incidents. In a test involving non-grade hardware store carriage bolts, they lasted only about 20 rounds from a 7.62 x 39 rifle at a distance of 50 yards on a 12 x 20 silhouette plate. The failure observed was exactly what grade 8 bolts are designed to prevent, bolt head shearing off resulting in target failure.
In summary, grade 8 carriage bolts provide the necessary strength and durability to withstand the forces generated by high-energy rifle rounds hitting plates. Their use, combined with low-profile heads and compatibility with square hole plates, contributes to a safer shooting experience with reduced splatter deflection.