Continental Rubber Works R-4 insulators make a good projectile for the Burn's Discharger Cup grenade launcher adaptor. Much better than tennis balls. They wont go the 100-325 yards of service grenades but a 100 yards is easily reached. They occasionaly tumble but often fly true with a wobble reminiscent of a fish swimming. The report and the recoil are mild. With service grenades the heel of the stock must be in firm contact with the ground but R-4s are easily hip shot. This is using generic blanks. With some modification to the insulator the insulator's range could be extended. R-4s on the spigot type rifle grenade launchers are a big disappointment. The tops tend to get blown off and you can throw an R-4 farther and with more accuracy by hand.

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