The Original Foam Stock Mod for Sniper Rifles and Shotguns
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c/o baymst, Airsoft Retreat, October 2007:
http://www.airsoftretreat.com/reviews/showproduct.php?product=216&cat=49
Contents
Introduction
One of the common concerns I here from snipers is that their rifle is to loud. Much has been written on how to silence the barrel of the weapon but very few folks think to improve the stock. When you squeeze the trigger the spring jumps forward creating not only air pressure but also sound and vibration, which is easily carried throughout the hollow plastic of the stock of the rifle. Some stocks are obviously much better than others but most airsoft rifles still have very large voids. Extra noise is generated by the vibration of the stock, not only irritating the shooter but providing yet another source of sound to give your position away. This mod is but one tool to add to the others available to quiet your beast!.
I have currently modded 3 rifle stocks. The first stock I injected was a UTG 870 shotgun. I had noted immediately upon receipt that it was hollow with glued in pig iron weighting. I'm not sure why it annoyed me but it did. Having used foam many times for various projects around the house it occurred to me that injecting the stock would give a more solid, more realistic and quieter gun, it did!
For this guide I will be performing the foam mod on my new MP001 and correcting the mod and finishing the exterior of my M324. The seams of the M324 were badly finished and the relatively thin plastic was not glued together very well. A perfect candidate for the technique. The MP001 that is made of a much heaver grade of plastic with far better seams, but hollow and way to light. I added the pig iron from the front of the M870, glued it in prior to performing the foam mod. I did not have to glue anything together on this stock.
Warning: Once the foam mod has been performed the stock can never be taken apart again so make sure your happy with the way it is weighted before you begin. Use only low expansion foam.
Background
I will be using various photos of the M324 and the MP001 and one of the M870 in order to give a more cogent process, the steps the photos demonstrate are in the proper order though. Each gun is designed differently but the concepts of the foam mod are the same. The primary focus of this guide will be the MP001 and the M324 which I have been gradually improving in the anticipation of partial or complete internal upgrades. I will refinish the the exterior of M324 removing many of its sniper like characteristics, slings, checkering etc. to end up with a rifle exclusively used for target practice. This rifle began its life as a V2 olive drab M324, purchased from Shorty USA like the one pictured below. The next two photos are of my pre-mod MP001 and my already foamed but not completed M324 with a rubberized coating. While I liked the rubber I liked the new texturized finish paint finish much better and will apply it to both. The M324 had some voids in the region of the cheek rest and I decided to correct that as well. Again, I am remaking both guns from the sniper role into target rifles. However you choose to finish your rifle you will never regret a well applied foam stock mod with an improved paint job.
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Supplies
- Great Stuff Insulating Foam Sealant by DOW
- Rust-oleum Textured Paint for plastic
- Krylon Matte Finish
- Krylon Fusion for Plastic Gray Satin
- Gorilla Glue or other that is sandable
- Bondo and a marine grade acrylic putty (I used 3M)
- Various grades of sandpaper down to at least 400
- Finger nail sanding pads (Optional)
- Copper wool medium to fine (Optional)
- Mineral spirits
- Duct tape, blue masking tape
- De-greaser
- Cordless drill with the appropriate size bit
- Various other tools
Cost can be from $10.00 to $30.00 depending on what you decide to do, and of course what products and tools you already have. The low expansion foam costs about 6 dollars.
Getting Started
Disassemble your gun completely. Remove the magazine, butt plate, trigger guard and of course the barrel and bolt assembly's. Depending on your stock gently sand any excess or rough plastic. You may also wish to sand down the molded safety and hop up instructions. I removed the sling mounts with a hack saw. Filling screw holes and seams takes place after the foam mod as the foam will expand and possibly crack the Bondo.
Sand the entire stock with a fine grade paper if you plan on painting. Wash the stock throughly with the de-greaser then finish with a good wipe off mineral spirits. Make sure to get into the seams and screw holes. Dry throughly. Water will seep into the seams of the UTGs so drying must be complete.
Injecting The Stock With Foam
Now you must determine where you wish to inject the foam. This depends entirely on what stock you are using as the different rifles have weights, chambers etc. which must be found and filled with foam. On the M324 and the M87 I used a combination of screw holes and holes drilled into the stock in various areas that I felt I could not be reached from the screw holes. The MP001 is more straight forward. This entire stock can be foamed with no drilling!
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The holes should be just larger than the application wand. Stick the wand in and move it around to determine the approximate size of the area you will be filling. The M324 needs to have the grip area completely full to avoid creaking. Don't worry about any drilled holes because you will later be filling them with Bondo or acrylic putty then painting. Obviously you do not want to drill into any areas of molded grip texture unless you will be removing them like I will or any structurally important areas. On the MP001 there is a ready-made hole into the stock under and just back from the receiver. This space is to lock in the trigger guard and will have to be cleaned out later with an Exacto knife.
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Practice with the foam first. Squirt some out and watch to see how much it expands and how long it takes before you begin to inject into the gun. If you put in to much into the gun it could begin to bulge, especially on the UTGs so be careful! Insert the wand deeply into the void you are working on and pull the trigger. As it starts to fill slowly withdraw it till the void is full. I worked slowly in sections and used the duct tape to keep weaker seams together. You will be filling these later so don't panic If some seams get larger. Let it expand for a period of time, then gently scrape off the excess foam. Tap the area with a finger or screwdriver and listen for any hollow sounds in the area you have just completed. If there are voids now is the time to fix them. Simply drill a hole into the void and repeat the process.
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When injecting foam into a screw holes fill till your satisfied the replace the screws and tightened before the foam has dried. Once an area is filled move to the next area and repeat the process. When the entire stock has been injected put it aside and let it cure for at least 24 hours. Once the foam has dried remove the tape and any excess foam with an Exacto knife. Clean any spill over or fingerprints with acetone or mineral spirits. Chances are very good, like me, you will have a few hollow sounding spots. Tap the entire stock again listening for hollow areas. If you find some repeat the above process until you are satisfied. Again, give it 24 hours to cure and your stock will now be solid as a rock! The foamed stock will be far quieter than your original! Darn important for a sniper!
Gluing, Filling Seams And Screw Holes
Once your happy with the foam job its time to degrease and clean the stock again and prepare to glue the seams. I hate the look and feel of seams and I did not much care for the rather poorly molded grips on the M324. Gluing seams was not necessary on the MP001 because it was very well sealed and the plastic much heavier than the UTGs. On the M324 I used an Exacto knife to scrape open the lose seams to give better adhesion. Then I use Gorilla glue to fill over all the seams. Stick a toothpick into seams that you can separate them, apply the glue and pull the pick out. Tape lose seams together with blue masking tape. Touch up and smooth the glue with your finger and let dry thoroughly depending on your glue. Let dry then sand the glued seams till smooth.
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Clean yet again and begin to apply Bondo to the seams, screw holes, voids and in my case the warning molding on the left side of the M324 stock as well as the molded grips. No holes or grips to worry about on the MP001 I just filled several deep seams and the areas where I had cut off the sling mounts. Make sure the foam in the open holes has been brought down below the level of the plastic before applying the Bondo. I used my finger to get the Bondo into the holes and voids. Let it dry for the appropriate amount of time. When dry use sandpaper and/or a finger nail file sand the excess Bondo down till you have a nice smooth surface. Clean the stock again and let dry. Check the entire stock for any voids or non-filled seams and, you guessed it, repeat the Bondo process again until you are happy. The M324 required almost two solid days of sanding and filling before it was ready for the first primer coat.
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Applying The Primer
When mostly satisfied with the stocks finish its time to spray on the first coat of primer. I used gray satin Krylon Fusion for Plastic, as my primer. Mask the areas that stock requires. Spray the primer on slowly in repetitions. When it has dried carefully check for minor imperfections and ad Bondo or the easier to sand acrylic putty to correct. The gray finish helps make easier to see any imperfections.
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Sand again and complete with a decent coat of the primer and let dry for several hours or more. I did over night.
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Applying The Paint
Mask again and get ready to spray your finish coat. My choice for my target rifle is a black texturized paint. Apply a light coating to the entire rifle. I then followed this with any immediate light coat of matte finish. These dry very quickly. I then used fine copper wool to take down some of the paint nubs. Then repeat the spraying and buffing process. I repeated at least 4 times with heavier final coats ending with the matte. Let it dry for 24 hours then buff with copper wool very lightly. Your now ready to put the beast back together!
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The Results
This process takes a while but I think you will be very impressed with the results. The results are amazing. No more stock flex, no more creaks and cracks while handling the weapon. The stock will now feel like a composite stock, which has become so popular in RS rifles, solid and quite! I think most people would really like texture as well no matter what the color scheme. When firing you will notice or should I say not notice the hollow cheap sounding vibrations coming from the bowels of your hollow stock! If your rifle is a CA, Maruzen, TM or any other spring sniper this should be an excellent upgrade. One of the side benefits is it will make your stock amazingly strong and break resistant.
Enjoy!
