The Spartan Classic Gunsmith Adapter is designed to be embedded / inlet into a rifle stock, and provide a secure low profile attachment point for a Spartan bipod or tripod

The information below offers some ideas and considerations for installing the adapter into rifle stocks that are produced in different ways (solid - hollow- carbon fibre.)

These adapters are produced by us in either aluminium or brass materials, depending on the finish the user is looking for. The dimensions machined cutouts are identical between them both,

The Classic Gunsmith Adapter is designed to work with the following Spartan products.

The rifle action needs to be removed from the stock to safely conduct this installation, and this is why we recommend customers seek the help of a professional gunsmith if they are not comfortable with the process for their rifles.

The key areas for a successful installation are to ensure that all measurements are taken precisely. 'Measure twice -cut once."

Ensure that the adapter is:

Each rifle is different in this respect, and time spent assessing the correct placement is well spent.

The adapter is designed to be fitted into the stock in a specific orientation. (See image below.)

Once the bipod is fitted into the socket of the adapter the machined cutouts with the socket can either allow the bipod to have a limited left & right rotation (this provides the user with muzzle traverse if desired.) Alternatively, if the bipod is fitted in the reverse position it will be locked in place, having no traverse, (good for range work, or longer range shooting.)

The two images below show the two machined cutouts of the Classic Gunsmith Adapter. (All of the 'Classic' range of adapters share this common 12mm socket design.) The pin on the side of the Javelin bipod cant block (all designs) is located in either of these cutouts depending upon the orientation that the bipod is fitted.

In the photo below how the adapter is positioned slightly further back along the stock to account for the up-turn of the 'Schnabel' fore-end.

Generally, though the further the bipod is located towards the muzzle, the great the stability in use is achieved, subject to the space available.

We are sometimes asked if the adapter should sit in front or behind the sling stud? Ultimately both options are suitable, but if you are a shooter that makes use of your rifle sling for additional stability whilst prone then you may wish to locate the adapter in front of the sling stud. If there is a lot of tension on the sling could conflict with the bipod if the adapter is positioned behind the sling stud

Consider the proximity of the existing rifle sling-stud to the position that you wish to locate the adapter needs to take account of the bipod when fitted and the ability to tighten or loosen the cant friction lever. If it is too close they may conflict with each other. This applies if the adapter is in front or behind the stud. Don't forget that the bipod can be fitted in the reverse position (180 degrees).

Consider if there is any internal or external chassis used in the stock? In the photos below the Sako, S20 stock uses an external chassis that is covered by a polymer outer shell.

Because of its design, the rear-mounted adapter needed careful positioning to fit into the limited space between the fixing points that are part of the chassis.

Additional ‘Gunsmith’ adapters are also often installed by customers who require a mounting option closer to the palace point of the rifle, for use with the 'Davros' heads or ‘Sentinel’, Ascent' & Hercules' tripod systems.

This second adapter can be beneficial when working in more confined positions such as tree stands or hides, or where a longer wait is anticipated. By locating the second adapter closer to the natural balance point of the rifle, it can allow the rifle to be pre-mounted for use, (whilst also being available for an instant freehand shot if required.) We've received positive feedback from users who endured some long waits on wild boar drives in sub-zero temperatures, who have taken advantage of this capability to keep warm but ready.

The rifle stock needs to be carefully masked up to protect its outer surface and firmly mounted upside down in a suitable vice so that the stock is level & perpendicular to the boring axis, thereby ensuring that the stock can be accurately drilled.

We like using ‘Devcon 10110 Type-A Plastic -Steel Putty, which is a two-part epoxy-containing sintered metal. We have found this to be extremely reliable & durable with good resistance to mechanical, temperature &, moisture. Being a putty, it is a little more forgiving when you require to work or shape it slightly as it cures. With some stock designs, it might be desirable to use an epoxy with less viscosity, which will find its way into small gaps & voids to achieve a strong & cohesive fitting.

There will be some geographical variations of what is available, and other good quality epoxy resin options also available, look for an option with properties that you require. These are likely to be the same products used when bedding in rifle actions.

It's important to ensure that the internal surfaces of the inlet hole & the outer surfaces of the adapter (where the epoxy contacts it), are keyed, cleaned & degreased. Keying the embedded surface of the embedded areas of the adapter will help the epoxy 'grab' & retain within the stock.

Ensure that any areas that you don’t want to get epoxy on are masked to prevent the resin from creeping and from bonding the two together.

Using an epoxy that is thicker in consistency is better in this respect than other more viscous epoxy resins. You may be required to make a small former or ‘bulkhead’ to contain the epoxy within the area of the stock you would like to fit it into. Using stiff cardboard or plastic cut to shape works well for this. And plumbers putty etc can also be moulded to form corners & shapes to contain the epoxy resin.

A simple soft wax applied to areas that are difficult to mask up or will remove later can work well in protecting surfaces that you don’t want the epoxy to stick to. (Neutral coloured wax shoe polish works well for this.)

The adapter is 17mm (0.6”) deep in total, but not all of this needs to be installed into the stock. If you look at the photos below, you will see that the rim of the adapter sits sightly proud of the stock, requiring only 12mm to be embedded into the stock itself.

The adapter is machined with channels that are designed to work with the epoxy resin bond agent to increase the strength of the bond. These channels are machined slightly smaller than the circumference of the top face of the adapter.

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The minimum depth that the adapter should be installed up to approximately 10mm (the lower portion of the adapter with the machined cutouts.)

Subject to the amount of headspace available between the base of the adapter and the bottom of the barrel, the adapter can be inlet deeper into the stock, and in some cases can be flush mounted. Care needs to be taken that there is no conflict with the barrel from the adapter or epoxy bonding material and the barrel.

A Danish customer of ours showed what is possible to achieve with time and the right tools, by sculpting his adapter to match the radius of his Sauer rifle.

In normal circumstances, this deeper type of installation can be achieved in most stocks where there is sufficient room.

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For boring a hole in rifle stocks made of solid material (typically wood or fibreglass), a 19mm ‘Forstner’ bit should be used. This is the most suitable bit for achieving a cleanly bored, flat bottomed, blind hole, which is essential for a solid stock.

Ideally, the boring process should be undertaken using a pillar/pedestal type machine, so that the correct X & Y axis of the bore is maintained throughout the process, and the hole is bored to the correct depth

This will produce a hole that provides a clearance fit, that provides sufficient room for the epoxy resin to form a good bond between the surfaces or the stock and adapter.

The image below shows a fibreglass McMillan stock, which offers the same strength as the solid wood stock for the adapter installation.

The good news is that these are the most straightforward stocks to fit the adapter into and tend to be the quickest installation to complete.

The link below this process being completed on the solid wood stock of a ‘Blaser’ rifle.

https://www.youtube.com/watch?time_continue=4&v=gfXRbB7W_ik

For rifle-stocks manufactured hollow stocks (typically polymer material, but not exclusively) an 18mm hole saw works well. The hole produced will be slightly too small and needs to be enlarged fractionally with a small rotary tool to produce a 'transition fit' between the stock and the adapter, which is gripped slightly by the rim of the stock.

The slight flex of polymer hollow stocks allows the adapter to be firmly pressed into place, providing a tight fit in the stock. The benefits of this tight fit are that the adapter is initially unsupported when fitted into the stock (unlike a solid stock), so the fit prevents the adapter from unintentionally moving out of alignment during the epoxy bonding & curing process. Another advantage is that the tighter fit helps to reduce the migration of the epoxy resin outside the stock, especially if a more viscous epoxy resin is used

Hollow stocks require a little more preparation work than solid stocks, as the adapter will need to rely upon the additional support of the epoxy resin as a bedding material to hold it in position and manage the energy of the rifle in use.

Often these types of stock are manufactured with several hollows or wells, divided by a series of cross braces (similar to the bulkheads of a ship). These hollows are an excellent place to use for fitting the adapter. The cross braces form perfect bulkheads to contain the epoxy and surround the adapter. Overall this process has similar considerations to pillar bedding in a rifle action.

Once the hole has been bored to the correct size the adapter and internal surfaces should be keyed, cleaned & degreased to provide the epoxy resin with a good surface to grab.

The adapter should be positioned so that it is orientated correctly and to the correct depth. Masking tape can be used to ensure that it doesn't move during the bonding & curing process.

A consideration for stocks that have a moulded structure that runs centrally along the length of the stock, (similar to the image below), is to fill the fitting area with epoxy resin before boring the hole. This effectively turns that portion of stock into the solid stock and can reduce the chances of the cutter 'wandering' as it moves over the thin polymer spine.

Some stocks have very little inside them and in these cases, it is a good idea to build up a larger body of bedding material inside the stock to support the adapter.

The image below shows a Weirauch PCP rifle stock. The wood is relatively thin along the base & hollowed out inside.

In this case, the adapter was positioned towards the front of the well in the stock to obtain as much support from the front face of the well.

A body of Devcon putty built up around it. This is a good example of where a thicker epoxy can be useful.

In these cases, the epoxy not only supports the adapter but also reinforces the thin material of the stock, which is relevant when the adapter is subject to loading when used with the bipod or tripod.

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Carbon fibre stocks can accept the fitting of the Classic Gunsmith Adapter, but careful assessment of their structural design needs to be assessed before starting the installation.

These stocks may be hollow or solid in design. All carbon fibre stocks will require extra care when drilling to avoid chipping the resin or catching carbon threads. It is important to ensure that the tools have sharp cutters.

These types of stock tend to have a thin shell formed by the laid-up carbon fibre material. Some designs of carbon fibre stocks are formed by laying carbon fibre sheets into a mould in the design of the rifle stock. If they have been formed using airbags or inflatable formers, that are removed once the epoxy resin is cured, then the stock is effectively hollow, so consideration should be given to providing additional support around the adapter.

In other cases, the stock is formed by laying up the carbon fibre material over a foam core that has been produced in the form of the finished rifle stock. These foam core composites are intended to produce extremely lightweight composite structures. while maintaining its lightweight and low water absorption.

In the image below you can see the foam core from a SAKO Carbonlite rifle. SAKO use a carbon fibre sleeve (like a sock with the toes cut off) that is slide over the foam core before the assembly is mounted into a press where the epoxy is injected into the carbon fibre weave. Once cured the carbon fibre material & epoxy creat the strong but light material we recognise.

Because the skin of carbon fibre material is thin, the 'point' loading created by mounting a bipod needs to be considered. This issue becomes more relevant if the intended rifle requires greater amounts of loading on the bipod during use.

In the image below, you can see the finished carbon fibre stock from a SAKO Carbonlite rifle now covering the foam core.

Because the foam core of the stock is relatively soft boring a hole and just bonding the adapter in place in the same way as a solid stock, can lead to the adapter moving as the foam core is compressed by bipod loading or recoil.

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Mix and apply the epoxy to the surface(s) according to the manufacturer's instructions, ensuring good coverage and fit the adapter in place and confirm that it is in the correct alignment. Consider using masking tape or similar to secure the adapter in position so that it isn't inadvertently dislodged whilst the epoxy resin cures.

With the adapter already pressed into position check, it is in the correct alignment. If the adapter easily moves in the stock Consider using masking tape or similar to secure the adapter in position. Mix the epoxy according to the manufacturer's instructions, and then fill the area around the adapter, ensuring that it if fully surrounds the adapter from the base to the stock to the top of the adapter and tamped so that the epoxy resin fully fills the void and not air bubbles are left. Ensure that the resin does not reach the rifle barrel. Once it has cured the adapter should is fully supported by the body of hardened epoxy material.

Wait for the epoxy to cure, remove the making material, clean & reassemble the action to the rifle & check zero.

I hope that this is of use to you, but if you require any additional information please let me know.

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