How to Maintain and Rebuild Bulk Caulk Guns (by Joe Shiffler)

To properly maintain your bulk gun, we’re gonna show you how to maintain it today. First, take off the front cap, you’ll see a conical ejector, a 7/16″ nut driver, or a wrench. Undo the conical ejector, 29-G28. Here you’ll see a lock nut, same size, undo. Turn the gun upside down, lock the recoil, pull the rod back a little bit, push it, the packing will come out. After use, set your washers aside. Clean your 21-1 leather cups in the manufacturer’s recommendation solvents. Let them soak in 10-weight oil or motor oil overnight, and you can rebuild the gun the next day.

Unloosen the 3-5 lock ring, undo the 237-10 barrel. Take the barrel brush 800-G01 or G02, turn it clockwise, clean the inside of your barrel. Wipe it out with a rag. Get all the residue off. Set it aside. Look at your gun. There’s a 5-1 lock ring in here that must be in there. Take your barrel, slide it into the back cap, screw it down until it touches the 5-1 lock ring. When it touches, lock your lock ring 3-5 against the back cap. You should feel a nice drag on a swivel, so you can swivel the gun.

Take a notice of your rod here, if there’s large notches, it’s a square rod so you can change it to get a better surface. Hold your hand over the recoil, press the recoil down, pull the rod out slowly turn it. Quarter turn. Slide it right back through the gripping plates, everything will be fine. Next day, take your leathers, 21-1s out of the oil. Pat them down, get all the excess oil off them, so it don’t drip all over. Have your washers set aside again. Hold the gun up. Take your small washer, slide it over the rod, it’ll stop on the chamfer. Take the leather cup upside down, slide it over the piston, drops in. Take your large washer, set it right on top. Take your other cup as a bowl, set it in here, 21-1. Take your small washer, lay it on top. Take your lock nut, turn it back on, screw it down. You can’t go too tight with this because if you go too tight, you’ll sandwich the leather against the wall and it’ll be too tight, you won’t get draw on your gun. So take it down hand tight.

Take your conical ejector, it will also act as a stop, a jam nut. So when you swivel the gun, you don’t undo the bolt. Lock that down. Take the gun, lock the recoil. Take the T-Pull, put it between your toes, and pull the gun, so you get draw like this and the gun works properly. At this point, you check and see how much drag you have in the trigger. If you feel that that’s too much, take a quarter-inch wrench, take the adjustment screw, turn it down till you get proper adjustment on the trigger, which is good and proper draw. And now the gun’s set back to the way we send it out in the factory.