All the design is his work, the pictures are mine. Credit goes to Slug.
1- 1 1/2" OD, 1/4" ID 1/16" Thick Rubber Washer
1 - 90126A509 - Zinc-Plated Steel SAE Flat Washer #6 Size, 5/32" Id, 3/8" Od, .036" Min Thickness = $0.97 per 100
2 - 91090A104 - Zinc-Plated Steel Large-Od Flat Washer 10 Screw Size, 7/32" Id, 1-1/4" Od, .042"-.052" Thk = $7.41 per 100
McMaster does NOT carry the correct rubber washer for this modification, but the steel washers they have are perfect. The rubber washers can be purchased from Lowes or Home Despot or any other hardware store that carries such things.
To clarify, that goes Small Metal, Large Metal, Rubber, Large Metal, Small Metal. That provides some extra backstopping on the plunger for those of you too lazy to do the CPVC mod below.
From Ace Hardware:
1 - Rubber Washer, 1 1/2" OD, 1/4" ID, 1/16" Thick [Ace #RM1214]=$.85 each.
2 - Flat Washer #6 Size, 5/32" ID, 3/8" OD [Ace #546563]=$.09 each.
2 - Flat Washer, 1/4" ID, 1-1/4" OD [Ace #546608]=$.29 each.
The last washer ID is 1/4" instead of 7/32", but it works fine.
Begin with a longshot plunger tube.
Remove the two silver screws from the back
Pull the plunger head and rod out of the tube and take out the front silver screw
Detach and set aside the stock plunger head, keep the screw
These are the materials used, including the stock screw
Cut a 1/4" piece of 1/2" CPVC and place it on top of the stock plunger rod. It should be a perfect fit, OD to OD. Then fill in the gap between the stock attachment point and the CPVC with hot glue.
Overfill the top a little to provide some back-pressure on the plunger head.
Arrange the materials as pictured, metal, rubber, metal, metal
Center the rubber washer on the metal washers for an even seal
Attach the plunger head to the stock plunger rod using the stock screw
View from the side
Re-insert the plunger head into the tube, it will be difficult because the washer needs to bend to fit into the tube, it will fit though and will provide you with a perfect seal for your longshot.
You WILL need an additional spring, or a more powerful one. A cut down AR-15 or a BBB or a MaxShot spring are all valid options. I personally prefer a LS+AR-15 spring combo.
Edited by hereticorp, 25 February 2009 - 08:37 AM.