Build yourself a fibreglass stock

There’s been a number of threads on this in the past, but I thought I’d put together a ‘build along’ on how I made mine.

Building a composite stock is something I’ve wanted to do for a while, and finally bit the bullet so to speak and got stuck into the project. I love the micro BSA .222 Hunter actions, and as most know they can be a bit fragile through the wrist. I have two of them, a good mate has two, and his son has two of them as well, so putting time into making the mould for one of these stocks looked worthwhile.

Overall it’s not a super difficult project, but it really does require a penchant for attention to detail. You’ll also want to be patient, as you’ll put a heap of man hour’s into it. I think I put close to 100hours into the mould alone, but once that’s done things get quicker from there.

So with that said, let’s get into it!

Step One
Prep the stock

Make sure you are happy with the stock finish, as any defects will be represented in the fibreglass copy. I spent some time steaming out dents, and giving the stock a refinish (London oil style) I filled the pores of the wood as much as possible, and got it down to a 0000 steel wool finish.

Step two
Build parting board

The mould was going to be vertically split, so a parting board needed to be made. I used 4mm MDF for this, and spent a good deal of time cutting and shaping it with a minimal gap around the periphery of the stock.
Attachment 168841

I built a box for the parting board to sit on, that also cradled the stock, so that the parting board and stock were held together in the correct position. The top of the parting board needs to run down the stock centreline. This is a good time to take some time and really have a think about how the mould halves will fit together, and whether your stock will be ‘trapped’ in the mould. Cheek pieces are a classic place for this.... in the next photo, you’ll see what I had to do to make sure the mould break line was in the centre of curvature of the top line of the stock.

Attachment 168842

Next, paint the parting board (top only) and get it to smooth a surface as possible. I used what I had left in the garage (metallic silver) and wouldn’t recommend it. It seemed to bleed out colour after it was polished with 1000 grit wet and dry, but worked ok in the end.

Attachment 168843

Step three
Fill inletting with plasticine

Once the parting board looks good, fill the gap between the stock and the board with plasticine. You want to make sure the transition is perfect, as that makes sure the split line of the mould is neat and square. Also fill the inletting with plasticine. It takes quite a bit, and a bit of time smoothing it out to look good.

Attachment 168844

Then make sure you create plasticine mould alignment pyramids every 3-4” around the stock. They are used to ensure alignment between the two mould halves.

Step four
Create the first mould half

A good layer of release wax is required now. Use as per the manufacturer instructions, I used 4 coats. Then a a good layer of heavy hold hairspray and you’re good to go

I used West System resin and hardener mixed with 406 silica filler to make a type of gel coat. This was brushed on all over the stock and parting board, creating a decent radius in all the sharp edges. This is critical to ensure there aren’t any voids in these areas, as the glass won’t conform to the sharp angles.
Attachment 168847

Once that has tacked off (is sticky to touch but doesn’t transfer to your finger/glove) use 6 layers of 200gsm plain weave fibreglass to cover the first half. Make sure you work all the air bubbles out with a stiff brush and or a roller. You’ll probably have to make cuts in the cloth to get it to conform to the stock shape (especially around the pistol grip) but you’ll work it out. Just be sure to make cuts of subsequent layers in slightly different places so the laminate remains strong.

Attachment 168848

Following.

Step five
Remove parting board

Once the first side has set (24 hours) gently remove the parting board leaving the stock in place attached to the first mould half. With any luck it will pop off easily.
Attachment 168849

Step six
Prep second half

Just like on the first half, now fill the inletting with plasticine. Also remove the plasticine out of the alignment pyramids, and clean them out nicely with a cotton bud or something like that. Pay attention to how you fill the bolt handle recess..... that one can be tricky depending on the stock/action design

Attachment 168851

Then repeat the release wax and hairspray schedule on the second side. Then apply the resin silica mix, then 6 layers of fibreglass as per the first side. Looking good!

Attachment 168850

The moment of truth!!!!!
Splitting the mould

After another 24 hours, you are now ready for one of the most exciting parts! Very gently start to pry the two halves of the mould apart. I find a little bit of warm water between then helps, as the hairspray is water soluble. Take your time, and be gentle with it. Work slowly around all the edges and it will come apart.

Time to inspect your work, and see how it came out. I was well happy with mine, even the checkering came out perfect.

Attachment 168858

Attachment 168859

Want to build me one for my BSA too?:D

Nicely done!!

Step seven
Prep the mould

Because I’m pretty OCD, I got some 1500grit wet and dry and polished up the inside mould surfaces. There was slight grain patterns left from the original, so I cut that back perfectly smooth to ensure an A1 finish straight out of the mould.

Next I stiffened up the mould halves with some pine stringers. Probably not necessary, but I wanted to make sure the mould wouldn’t warp at all. After that I opened up the area above the barrel channel so that glass strips could be laid in there when the two halves of the stock are joined together.

Then I used 10x M6 bolts and wing nuts evenly spread around the edges to hold it all together.

Attachment 169064
Attachment 169065

very clever wee womble you are..... most impressed. and you have order for a finished stock already....yip will pay you for your time very quickly.

i for one am seriously bloody impressed !

I love these inspirational threads, I’m looking forward to the next part. ��

Thanks for the kind words guys. I leaned quite heavily on others that had been before me, and am very grateful for their help.

Paying it forward, I’m more than happy to pass on what I learned to anyone that wants to give it a go themselves.

Step eight
The good sh*t!!

Right lads, time to really roll up the sleeves and get serious! It’s time to build a stock.

Mould prep is slightly different at this stage, still the same 4 coats of release wax, but this time we will put on a layer of PVA release agent. This makes for a slick release and also a good surface finish. In between coats of wax, start cutting out the layers of cloth that will make up the stock halves. For the first one I built, I used 4 layers of 200gsm plain weave cloth. I did each layer in two sections, forend and buttstock, with about a 10-15mm overlap in the grip area somewhere. I also used (from memory) 3 extra layers through the pistol grip area. There is a couple of key points to note here:
1. Make sure you stagger the overlaps in slightly different places, so there isn’t a large build up of glass thickness in one place.
2. Change the orientation of the cloth between layers, so that the stress is carried through the cloth in all directions. In other words lay some layers with the weave at 0/90deg and some at 45/45deg.

Once the release agent is dry, then it’s time to once again apply a good thick ‘gel coat’ of thickened resin to each mould surface. Make sure and create a wide radius in the bottom of the grip cap and around the top lines of the stock next to the barrel channel. Basically anywhere there is a tight bend that the glass will struggle to conform to. I did this as much ‘diy’ as possible, so there is no vacuum bag gear involved. Your stock will be a bit heavier with this method, but I wanted to keep things simple.

Wait for the gel coat to tack-off, then get stuck in to the lay up. Again, pay particular attention to the corners, and be sure to work out all the air bubbles. After an hour or so of work, you should see something like this;

Attachment 169096

Step nine
Trimming and joining the halves

Right, now that the two halves have been layed-up, it’s time for a bit of waiting..... What you are waiting for is for the resin in the laminate to harden enough that you can cleanly and easily trim the laminate flush with the joining surfaces of the moulds. For the resin and hardener that I was using (West 105 resin with 206 slow hardener) it worked out at 2 hours post laminating was about right. You’ll know it’s too early because the resin will leave gummy deposits on your blade, and you’re too late when your blade won’t cut it reasonably easily. A good sharp Stanley knife is sufficient.

With that done, make up a thickened resin glue mix (I used west 403 filler) and apply to the freshly cut edges where the stock halves will join together. Now, bolt the two mould parts together nice and tight. Once that is completed, I layed two layers of glass cloth over the join from the inside. About 50mm wide is plenty. The forend is easy, buttstock more difficult, and the pistol grip really bloody fiddly. I made up a tool to help smooth the glass out inside the stock, which was basically a coat hanger bent to the appropriate shape with a loop on the end.

Once that’s all done, have a bit of a cleanup and crack a cold one, you deserve it! The best bit comes the next day......

Step 10
The big reveal!

There is just something special about breaking a composite part out of a mould. I know I’m addicted to it, it never stops being exciting for me!
After at least 12-18 hours, you can undo the bolts on the mould and gently break the halves apart. This should happen pretty easily, but if not, a wee bit of warm water will help as PVA release is water soluble. With any luck you now have a hollow shell that is a perfect replica of your original.

Attachment 169165

Attachment 169168

I had a few defects with my first one because I didn’t use a thickened coat of resin first. It was all able to be fixed, but just added a bit of time to the project. The following pictures will illustrate the usual places that you’ll get caught out....

Attachment 169166

Attachment 169167

So what did Mk.1 weigh roughly Nick?

@6x47 the first one came out at 735g finished with recoil pad. Pretty good really, but it’s a fairly slim stock so the dimensions helped there.

Original in walnut was right on 1000g

You could try using one of the vacuum storage bags you can buy off Trademe. You’ll need to put some peel ply on the fibreglass then some old sheet or similar on top of that. It will squeeze some of the excess resin out.

Thanks for that @stug great input for those looking to try this. I had access to a full vacuum bag setup, but decided to see what I could achieve with the bare basics, for no other reason than just because. I tend to like the K.I.S.S principle!

Step eleven
Making the inlet moulds

Now this bit was theoretically easy, but in practice just about broke me! I’ll get to why that was shortly.

Anyway, the idea with this step is to cast a two piece silicon rubber male mould of the inletting. This is made of an upper and lower part that will eventually be clamped into the hollow stock, and then thickened resin poured in to create the inlet.
What you do is create a plasticine dam around the edges of the inlet and dam up one half in the mag well/trigger well as in the picture. Note the locating indentations in the bottom.

Attachment 169246

Once that is done mix up your silicone and pour in as directed by the manufacturer. I used Mold Star pourable silicone.

Attachment 169247

Once cured, build plasticine dams for the bottom half, remove the plasticine dams in the mag well etc, and pour the bottom. Make sure you use a release agent designed for silicone to ensure the two halves do not stick together.

Attachment 169248

Once it’s cured, you can remove both halves out of the stock and you should have a perfect imprint of the inletting. Not like this however!!!!

Attachment 169249

For some reason the silicon cure was inhibited. Sulphur is the main culprit, but I didn’t expect that to happen on a walnut stock. I spent hours cleaning off the gooey residue, and cleaned the inlet thoroughly with Acetone. I then painted on a thin coat of clear acrylic lacquer, and tried the whole thing again. Much to my dismay it failed to cure a second time! Albeit better than the first attempt. It was at this point I almost gave up...... but instead used the castings I had to ‘roughly’ cast the inlet on MK1 and then carefully hand filled and sanded the inlet to the right dimensions after it cured. I also bedded the action into the MK1 composite to get a good basis to silicone mould from. It was laborious work, but got there in the end.

Attachment 169250

I use to make the action inlet mold the same way, but after a few uses the silicon ripped apart. I then swapped to useing silicon sealant you get in the tubes. It is a bit of a bugger to work with but is heaps cheaper and a bit more flexible and easier to get out once you have cast the action area.
I did a two part cast like you have, smear the silicon thickly around the edges making sure to push it down into the corners, then leave that to set then fill in the rest. It does take a couple of days for the silicon to set right through.
I put petroleum jelly on the action first to act as a release agent.

Quote:

---

Originally Posted by stug

I use to make the action inlet mold the same way, but after a few uses the silicon ripped apart. I then swapped to useing silicon sealant you get in the tubes. It is a bit of a bugger to work with but is heaps cheaper and a bit more flexible and easier to get out once you have cast the action area.
I did a two part cast like you have, smear the silicon thickly around the edges making sure to push it down into the corners, then leave that to set then fill in the rest. It does take a couple of days for the silicon to set right through.
I put petroleum jelly on the action first to act as a release agent.

---

Was your release agent for the stock moulding petroleum jelly too?

Quote:

---

Originally Posted by Tuidog

Want to build me one for my BSA too?:D

---

@Tuidog there’s a chance that something might be able to be arranged.....

Just moved house, so life’s a bit hectic but maybe in a wee while

Quote:

---

Originally Posted by Tuidog

Was your release agent for the stock moulding petroleum jelly too?

---

@Tuidog I used maguires release wax, I think it is a car wax.

Quote:

---

Originally Posted by Hunter_Nick

@Tuidog there’s a chance that something might be able to be arranged.....

Just moved house, so life’s a bit hectic but maybe in a wee while

---

Awesome. Even just the shell and I could carry on and finish. Just ordered a walnut stock today which will require some finishing.

Sent from my SM-A515F using Tapatalk

Step twelve
Creating the inlet

Now that you have a hollow shell and inlet moulds, it’s time to get ready to make the inlet for real. There are a couple of prep steps before hand however.
1. Block off the rear of the action area at the start of the pistol grip. This is so when the epoxy is poured in, it doesn’t flow all the way into the buttstock area. I used a piece of fibreglass sheet that I laminated up earlier from 6 layers of 200gsm cloth.

2. Grind/sand the edges of the inlet area, so the moulds will fit in without distorting. I used the action and floor plate to check that, and made sure they fitted in nicely but without too many gaps.

Once that’s all done, rough up the inside of the shell slightly with some 80-100grit, and secure the mould halves into the shell.

Attachment 169348

With the stock secured vertically you can make a batch of thickened resin to pour in. Now this part is VERY important!...
****** Thicken the resin as much as possible to reduce its density (weight) but still ensure it is runny enough to flow. Also, only pour in small batches! If you fill the whole cavity, the resin will exotherm and probably go up in flames! West resin isn’t designed for thick pours, so just do a little at a time, and wait for it to cure enough that pouring the next lot on won’t create a cumulative heat issue. *********

Once it’s all cured, pull the moulds out and voila!

Attachment 169349

Attachment 169350

Step thirteen
Mould the barrel channel

We’re almost there! Now it’s time to take a mould of the barrel channel, so we can create a liner for the forend. For my stock it was a bit of a pain, as the BSA factory hollows out the forend to relieve weight. I had to first fill that with plasticine before coating in release wax and then PVA. It also has that little bugle for the rear sight which made things a little niggly too.... I made the mould from 6 layers of cloth, and once set, trimmed and fixed to a scrap of wood so it was easy to secure.

Attachment 169351

One the mould is done, do the standard mould prep and laminate the liner from 4 layers of 200gsm cloth.

Attachment 169353

Again, once cured trim and release from the mould.
Now it’s time to trim the inside edges of the stock shell in order to get the forend liner to fit. This can take a while, as you want to make sure that it is straight and providing an even free float along its length. I did plenty of test fitting with the barrelled action in place. It likely some dremel work will be required on the inlet epoxy, so that the barrel liner will sit on it at the correct depth.
Don’t forget to put a sling swivel stud in if you want one! I added about 4-6 extra layers of glass in that area to ensure it was good and strong.
Once your happy, glue the liner in!

Attachment 169354

Step fourteen
Recoil pad

Remember how I mentioned a piece of flat fibreglass plate earlier? Well some more of that is required for fitting the recoil pad.

I cut and trimmed a piece so it would fit snugly inside the end of the buttstock, about 3-4 mm inside the finished edge where the recoil pad would mount. I glued this in with a generous scallop of resin ‘glue’ mix and let cure. I then filled that recess with a resin and micro balloons mix, and when cured sanded flush and square for the recoil pad to mount to. This seemed to me to be the best compromise between strength and weight.
Chose the recoil pad you want and mark the holes on the stock for the mounting screws. Drill the holes oversize (around 10mm) as we’re going to use then to pour in expanding foam.

I bought a 2 pack polyurethane expanding foam kit, and used that to fill the buttstock area. You don’t need a lot, only about 4-5 tablespoons is enough to fill the area once it goes it’s thing. Once cured, use the same drill that you drilled the recoil pad holes with, and deepen the holes into the foam to about 15mm deep and fill with thickened resin. This will provide a good stable and strong place for the recoil pad screws to hold on to.

Them just mount and grind your recoil pad as per usual. Be careful though, fibreglass doesn’t handle a belt sander as well as walnut if you get a bit loose grinding the pad!

Attachment 169355

Oh yeah, and don’t forget to add something inside the stock in order to screw the rear sling stud into! That needs to be done before you close the end of the stock in.

Some people also fill the forend with foam, but given the small dimensions of the BSA stock I chose not to.

Step fifteen
Pimp it out!

So now you have your stock basically done. Only thing to do now is give it some colour! I got lazy and rattle canned mine with some Matt Black Wattyl Kill Rust epoxy topcoat. I just keyed the stock surface and sprayed it on. It has stood up to the punishment pretty well so far, so I’m happy enough.

Attachment 169356

Attachment 169357

So there you have it. As you can see, it’s an achievable task if you take your time and get your head around how each step fits in with the next.

There’s a few guys around that have done one of these, but if anyone wants a bit more info I’m happy to pay it forward as others have done for me.

Cheers lads, have fun with your projects!

Epic thread. I'm loving it

Sent from my SM-A515F using Tapatalk

Nice finish. You could add some black pigment to the initial “gel coat” you put in mold. That way you wouldn’t need to paint it or if you did paint the scratches wouldn’t show up as much.

Thank you for an excellent post. Very much enjoyed following progress.

Quote:

---

Originally Posted by stug

Nice finish. You could add some black pigment to the initial “gel coat” you put in mold. That way you wouldn’t need to paint it or if you did paint the scratches wouldn’t show up as much.

---

Yes I had contemplated that, will probably try that on the next one!

Quote:

---

Originally Posted by Husky1600

Thank you for an excellent post. Very much enjoyed following progress.

---

Thanks for your kind feedback. I just hope it is helpful to someone else who is keen to give it a go.

I have some black pigment I can send you if you want.
What is that mag on the the rifle on the picture with the stag?

Quote:

---

Originally Posted by Friwi

I have some black pigment I can send you if you want.
What is that mag on the the rifle on the picture with the stag?

---

It had an custom made extended mag for it then. I’ve since changed it back to standard 4 shot internal mag with floor plate. The extended mag wasn’t detachable, so had to work the rounds through the action to empty the mag.

Thanks for the offer! I’ll let you know when I make another