DIY MK1&2 / LD / S&W 78G & 79G Stock...
I have made a couple of these in the past and needed another one, so I thought I would let others know how make a really nice stock for around $75. Cheaper if you happen to have some of the materials needed at hand already. Please read and re-read the step-by-step instructions to make sure you do not make a mistake and waste parts and money.
Right up front, I will tell you that this stock setup works best with an adapter that WAS available from MAC1 Airguns and Baker Airguns.
Baker (Black), MAC1 (Brass).
Baker Airguns has been out of stock for several years and MAC1 had them, but no longer has an online presence.
A 30mm ring can be used on the original CO2 cap from either the Mark 1&2 or the S&W 78G & 79G airguns. There are some issues to consider first...
The outer diameter of the early style, toggle, Mark CO2 cap, is 1.138" and the width of the knurled portion that the ring will clamp to is 0.374", just shy of 3/8".
The later designed, push button CO2 cap, has an O.D. of 1.136" and the width of the knurled portion is 0.443, just shy of 1/2".
30mm = 1.1811" and is slightly larger than the O.D. of either CO2 cap and will require some tape buildup to make it solid and secure.
The S&W guns have a CO2 cap O.D of 1.125" with a knurled width of 0.210" and again, some tape buildup will be required.
In all cases using the CO2 caps, I used a UTG 30mm ring that had a width of 0.870", quite a bit wider than the knurled area of each CO2 cap. With the ring edge mounted flush to the inside edge of the CO2 cap, edge closest to the gun, I noticed that the toggle or push button on either the Mark or S&W guns was well below the outer edge, (Bottom) of the ring and may present issues with piercing the CO2 cartridge. The toggle did look to be more favorable though in this regard and could be accessed more easily. I was able to move the lever fully, side to side and observe the puncture pins' movement. I did not however, actually try it out with a CO2 cartridge in a gun. The push button issue should be able to be easily solved with a little ingenuity from the end user.
The ingredients -
Crosman 1399 Shoulder Stock - $26 eBay
UTG 1" or 30mm Lever Lock Rings (Pair) - $25 eBay
Marlin 336 Picatinny Rail (Not Weaver) - $10 eBay
Gorilla Glue 5 Minute Epoxy - $7
(1x) 6-32x3/4" Fillister Head Screws - $5 ACE Hardware (For All)
(1x) 6-23x1-1/2" Fillister Head Screws
(1x) 6-32x2" Fillister Head Screws
(3x) 6-32 Hex Nuts
(5x) 6-32 Square Nuts
Dozen BBs or Pellets
Painters Tape or Equivalent
Fine (240) Sandpaper (Sheet)
Paper Towels (Couple)
Cutting The Stock -
I matched the angle of my stock with that of the Crosman stock. I saw no need to try anything else. As far as where to mark the stock for your cuts, I have measured one of my finished stocks and have done the hard work for you.
The upper cut mark should be 11-3/4", straight line even with the top of the wrist of the stock to the back of the butt. Yes, it will be measured from that curved portion of the butt. Make sure the measurement is from the top of the stock and not on the side.
The lower cut mark will be 11-3/16", straight line even with the lower edge of the stock, tight into the grip. These marks were then marked with blue tape or equivalent to the proper angle.
I used the edge of the tape as a line and cut the stock easily using a fine-toothed hack saw. Be careful and work diligently... Haste makes waste!
IMPORTANT NOTE - The butt of the stock is thinner than the grip/wrist area. Just placing the stock flat on the bench will give you an angled cut. Make sure to prop up the butt and level the centerline of the stock before cutting. The old rule of measure/check twice, cut once, still applies.
Once cut, the rough-cut edge can be smoothed and evened out using a sheet of Fine, 240 grit sandpaper, laid flat on the bench, then carefully, pressing the stock cut flat into the sandpaper and sand with a front to back motion, using even pressure, until the saw marks are removed. Check your progress every 6 swipes or so. Any edge feathering can be scraped away using a knife blade.
IMPORTANT NOTE - Before sanding, just place the stock cut flat on the bench and check whether or not the stock is sitting straight up (Plumb), as it should. If it has a slight cant to one side, while sanding, place more pressure on that longer side to make it even with the other. I would only give it a couple of swipes before rechecking the upright angle. It doesn't take much to remove too much! Once it has straightened out, finish sanding both sides flat until the saw marks are gone.
The Marlin 336 Picatinny Mount -
The Marlin 336 Picatinny scope rail has a flat back to it. Others are curved to match a certain gun's receiver, so only use a Marlin 336 scope rail. Picatinny rails have lots of slots, Weaver rails only have a couple, use Picatinny for maximum amount of adjustment.
The 6-32 screws will go in the top 3 of the 4 holes on one end. 3/4" screw first, 1-1/2" next and the 2" screw last. Jam tight all screws to the base with the 6-32 hex nuts. Before mounting the screws to the base, I painted the screw heads black to match the base, that's your choice.
The Square nuts should be spaced as shown in the picture above. They will ensure that the screws will never come loose and pull out.
Epoxy & Glue Prep -
Before mixing the epoxy, take a small wad of paper towel and pack it tight into the bottom of the stock hole to block the deeper open passages in the stock.
Take your now prepared mount and do a dry check. I found that once the mount was held flat and tight in the stock hole opening, pushing the mount forward and jamming the hex nut against the stock, was the perfect forward placement.
You will notice the mount going about 3/16" past the edge of the stock. That's what you want.
Now, while dry, check how the mount sits on the sides of the cut, any issues that need to be corrected? Also, once the glue is poured, you won't have a lot of time to fidget and fumble. You will need to align the mount with the stock and then hold it for 10 minutes or so to allow the glue to gel enough, so the mount won't drift when released. That sounds like a lot of time, but it wasn't difficult at all and went by pretty fast.
To align the mount with the stock, I held the stock upside down and then visually aligned it, using my dominate eye, the end of the mount, top and bottom, with the toe (Rear bottom corner) of the stock and the front of the comb (Front top edge).
Prep a place to put the stock for 24 hours, allowing the glue to fully cure. The mount once glued into the stock, should be held in a straight, plumb and level position.
Keep those pellets or BB's close at hand as you will need them once the glue is poured.
The Gorilla Glue came in a tandem syringe, mix all of it at once. Once mixed, pour the glue into the stock hole, stopping about 3/8" from the edge. Wipe any glue glop from the edge cut. Now, place the mount screws into the glue slowly and place the mount flat against the stock cut.
Lean the mount slightly to observe the level of the glue. Ideally, it should be perfectly level with the top edge of the stock hole, with the mount fully in place, without any oozing out along the sides the mount. The glue level can be raised by simply canting the mount to the side enough to drop in a few pellets or BBs as filler.
Once the glue level is raised, now align the mount to the stock and then hold the stock and mount firm for 10 minutes or so. You will feel the stock heat up as the epoxy cures, that reaction creates heat. All good!
Adapters, CO2 Caps & Rings -
The lever lock rings have a lever that sticks out from the side of the ring once tight. I chose to mount the ring, in all applications, with the lever facing upward once secure. This will keep it out of the way and prevent it from snagging on something once locked. Also, I am right-handed and found that by mounting the lever on the left side of the grip, it placed the lever in the open portion of my grip and not in the palm of my hand. For lefties, the lever will have to be facing downward on the right side of the grip.
A UTG 1" Lever Lock Ring was used for both the Baker Airgun and MAC1 adapters and required no tape, they both clamped nice and tight. For all but the MAC1 Adapter, including the CO2 caps, the edge of the ring, flush with the edge of the Baker Airgun Adapter or any CO2 cap will then place the ring so close to the frame and grip, that they could be damaged while screwing it in. To prevent this, I installed a fat O-ring over the adapter/cap to space it out and stop it from marring the gun. Don't worry if the adapter/cap isn't tight, snug is good enough. The 900 psi of the CO2 will lock everything up rock solid once the gun is charged. The MAC1 Adapter is long enough to keep the ring, once tightened down, about 1/4" away from the grips and frame, so no O-ring is required to prevent damage.
Baker, MAC1 Adapter & 1" UTG Ring.
Using With Multiple Guns -
I started using my first stock between several guns. The issue I found was that the ring position on the adapter/cap, once in the proper stock alignment position for one gun, wasn't always the same once tight, gun to gun. Test and mark the tight position on the adapter for each of your guns. Then, mount the ring in the correct stock alignment position on the gun with the mark furthest counterclockwise as you look at the open tank portion of the adapter. The maximum difference for all my guns was about 1/2 turn in and worked for all my guns. That means all the other guns except that one, the adapter will not be tight in the gun, but snug and the stock will move. Again, snug is good, as the CO2 pressure once the gun is charged, locks it up tight.
Because of this variable, what I do is, before charging with CO2, I hang the gun in my hand by the stock and visually align the gun and stock. Once aligned, I hold the gun by the grip only, then charge the gun with CO2. This will lock the stock up nice and straight. Simple enough!
Other -
The nice part about using the Picatinny rail with plenty of slots, is that you can raise or lower it for scope, dot sight or open sight use. On many of my guns, I use See-Thru rings, so I can use either at a whim. Being able to adjust the comb height of the gun, gives you better eye/scope/sight alignment and a better cheek weld which aids accuracy.
Well, thanks for humoring me. I hope some members can use this to make a stock for their Mark, LD and S&W pistols. I have been told that doing the first of anything, takes the most time. Then the rest to follow are quicker to do because you have a plan and a rhythm... Yah, right!
H&BGuy
