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Production of OEM Components

Posted by Administrator on 2/2/2015

In late 2013 we began a program to change many of our manufacturing processes from the CNC machining of component parts to investment casting them, and then doing minor secondary machining of these cast parts on the critical surfaces.

Two factors drove this project; one was the continuing availability of imported PSL parts, which is the base platform that three of the four firearms we manufacture are built on.  The second issue was the cost of manufacturing components.

Out of the 20+ components we identified to go through this process, we started with the front sight / gas block for our new Krinkov (BHAKR39), as they were impossible to get at the time from Russia or Bulgaria.  The following pictures show the casting steps for these.

The investment casting operation begins by injecting molten wax at very high pressure into a mold of the part to be cast, which is called a plug.  A mold and the wax injector can be seen in the foreground of this 1st picture.

We've worked very hard to produce reproduction parts that are within +/- .001" to .+/- .002" tolerances of the original component.  With shrinkage occurring in both the wax when the is plug injected and cools, and shrinkage of the molten metal when it cools in the mold, these factors are taken into consideration

The wax plugs are mounted onto a wax tree with hot wax as the glue to hold them on, which is seen here as the greenish brown post with angled base. .  The wax tree with the plugs are then coated with about .250” thick of ceramic stucco and fired in a kiln to turn the wax to ash.

After being blown out with compressed air, this ceramic vessel becomes the mold.  It is then inverted with the base in the up position when being cast and the base becomes the funnel that the molten metal is poured into.

The wax cylindrical shaped piece seen coming off these parts becomes the gate where the wax enters the mold, and is also used as the gate when attached to the wax tree for casting the molten metal into the mold.  This gate gets ground off after casting.

The entire process starts with doing 3D CAD models of the component, and with these a mold is made, using CNC machine centers, that is very similar to a plastic injection mold.  The difference is they are machined out of aluminum versus steel, and the material being injected into them is hot wax as opposed to polymer.

This next group of pictures show the wax plugs and finished product for the bracket that goes on the front of the Vepr lower forearm.  We started out CNC machining these, and the cost difference between that and casting is less than half with no sacrifice in quality.

The following pictures show the wax plug for the PSL muzzle break, along with a finished part.  The threaded version of this is virtually non existent on the surplus gun parts market and these reproductions allow us to continue installing them on our BHAK54, versus the pinned one seen below.

These next images show the wax plugs for the forward SVD forearm bracket in our conversion kit.  The rear bracket is still in the tooling stage for making the wax plug.  The image of it on a PSL shows the original style incorporated with our early version of the BHA Short Stoke Gas System.

These next images of the Vepr Slant Back Trunnion Adapter have been part of a process that began in the summer of 2012.   Having had multiple failed attempts at getting this part correct, we have continued to make revisions to our mold and are satisfied now that we have it right.

These first images show the 2nd generation one being CNC machined, which was extremely cost prohibitive.  The following images show the wax plug and a pile of adapters fresh out of the mold after media blasting.  The secondary machining on these still needs to be done.

Our Short Stroke Gas System has been another ongoing project since the fall of 2012.  The original design was an attempt to solve the issue of cutting off the forearm brackets of the PSL gas tube in order to install the SVD Forearm Conversion, as seen in the earlier picture.

The gas tube in our design was a .590" OD smooth bore cylinder with a .550" OD puck like in the Saiga-12, which pushed a spring loaded .195" OD OP rod and cycled the modified bolt carrier with no piston on the front.  The tube had adjustable gas ports to relive pressure, similar to what the ridges do in a Kalashnikov gas tube.

The tube installed into the front gas block and locked into the rear sight block identical to a conventional gas tube.  Because of the thin diameter of the tube, using it in combination with SVD forearms and forearm brackets allowed one to drop it in without making any modifications inside the SVD forearms for clearance.

Our BHA54s (see brochure) uses a modified SVD gas system with three adjustable gas settings, and after introducing this firearm we realized Izhmash had it right and there was no need to reinvent it, so our redesigned Short Stroke System's components are patterned after the SVD gas system with minor modifications.

We’re doing a separate post on just the Short Stoke System so to not be redundant we won’t go into detail at this time, but the following pictures show some of the items that are completed in this redesign.  The bolt carrier that accompanies this systems and modified bolt carrier return spring are the only items yet to be completed.

The following pictures show the Short Stoke System installed on our BHAK54

With over 20 items involved in this new tooling project we're about half way through the process.  Two items that are high on the top of the list are investment casting molds for our SVD Front Sight and Flash Hider.

We've been CNC machining these and the cost is just too prohibitive to continue doing this and be able to sell them at a price that makes any sense.

We will continue to produce the SVD Flash Hider this way until the molds are complete to investment cast them, but we've temporarily taken the SVD front sight out of production until we have the molds for it completed.

As we have additional information on other projects that are part of the new tooling process we will be posting updates!