Thursday, April 15, 2010

Nerf Recon "Brass Breech" Mod Guide!

Due to popular requests, here is a mod guide for the "Brass Breech" modification for the Nerf Recon.

This mod is also applicable to other Nerf N-Strike blasters with reverse plunger setups (ie. Raider, Deploy, Longstrike, Alpha Trooper etc).


For a background of what a Brass Breech is and what it does, please refer to the Longshot "Brass Breech" Mod Guide.


This mod guide will look very similar to the Longshot "Brass Breech" Mod Guide as they follow a similar modding process, but there are some specific differences in parts measurements, positioning and fit that modders will have to take note of.

To establish expectations, due to the smaller reverse plunger setup in Recons (or any of the other reverse plunger blasters), the potential performance gains will naturally be much less significant than in a Longshot.

Important Note:

The "Brass Breech" mod is a more advanced mod project that should only be performed by those who are already familiar with modding the Recon.

For new modders, refer to the Nerf Recon Mod Guide to get familiar with the modding basics first.

Disclaimer: Modify at your own risk. Modifications may wear out or damage your blaster. Please be careful when using hobby tools!

Lets begin...

Step 1:

You will need to obtain 4 different sizes of brass tubes (Brand: K&S Engineering).

The brass tube sizes are: 1/2", 17/32", 9/16" and 19/32". All of them are 0.014" wall thickness. They are usually supplied at hobby shops in either 1 ft or 3 ft length tubes.

Oxidization tends to occur in store bought supplies, so give the brass tubes a good polish with some Brasso Metal Polish, polish both externally and inside the tubes, this helps smoothen out the surfaces for lower friction.

Step 2:

We will work on the barrel and bolt receiver first.

In this example, i'm using 7" of 9/16" brass tube for the barrel.

Take a Rotary Tool with a cutting wheel, and cut a 7.5 cm length bolt receiver half-pipe in the 9/16" brass tube. The effective barrel length will be 4".

Use a sanding bit to round out the edges and corners.

Please be careful when handling such hobby tools, wear protective eyewear, dust masks and gloves.

Step 3:

To help the chambered darts achieve an even tighter air seal, make tightening rings in the barrel.

Use a Rotary Pipe Cutter and create the tightening rings. Just tighten the pipe cutter slightly around the brass tube, then rotate. Do it a few times to create the tightening rings.

Okay, that's all for the brass barrel and bolt receiver, you can put it aside for now.

Step 4:

We will now go on to the bolt section of the breech.

Separately cut out a set of brass tube sections in the following lengths:

1/2" brass tube: 10.5 cm
17/32" brass tube: 3 cm
9/16" brass tube : 2 cm
19/32" brass tube : 14 cm (4 cm for bolt half-pipe)

These are my custom tube measurements for a breech system for the Nerf Recon that can chamber standard-sized darts. In addition, it also features a more secure "half-pipe" bolt attachment point design.

The measurements need to be as accurate as possible. Any variations may affect the overall structure and air seal of the breech system.

Step 5:

Cut the original stock plastic bolt at the section shown below.

Nest all the 4 brass sections for the bolt completely into the plastic bolt end-piece.

Here is my Nested Brass Tubes Cut-Away Diagram for the Nerf Recon:

Use the strongest glue you can get to glue everything together. I use slow-curing 2-part strong epoxy glue. Make sure the glue cures completely for maximum bond strength.

Completed nested brass bolt assembly.

Nested brass bolt internal assembly.

Step 6:

We will now need to do a test alignment of the various components.

Secure the brass barrel inside the original orange plastic barrel by wrapping it with electrical or duct tape to temporarily widen it's outer diameter, so that the brass barrel can be wedged tightly inside the plastic barrel, yet still movable to allow adjustments for test fittings.

Check all the part positions and make sure that a clip with a standard-sized dart can fit nicely into the breech opening.

Note that the 19/32" brass bolt half-pipe will slide over the 9/16" brass barrel half-pipe, which in turn slides into the brass bolt assembly.

Step 7:

To attach the brass bolt to the bolt sled, we will need to cut out the attachment piece from the original plastic bolt.

Position the brass bolt, attachment piece and bolt sled in the casing and note the maximum forward and backward movement of the bolt to find the correct point to attach the plastic attachment tip to the brass bolt.

Note that a segment of plastic behind the attachment point has to be trimmed thinner so that it can slide into the plunger casing properly. Just whittle it down until it fits.

Use some sandpaper to roughen the surfaces on the plastic attachment tip and brass bolt, then use the strongest glue you can get to glue the 2 parts together. Again, i use slow-curing 2-part strong epoxy glue here too. As always, make sure the glue cures completely for maximum bond strength.

This is the section that has to take the most load, especially when stronger springs are used.

Step 8:

Assemble everything together into the casing, note that the pop-up blocker plate mechanisms are all removed, we don't need those anymore.

Step 9:

Test your "Brass Breech" Recon!

Breech open.

Breech closed.

Once you are confident that everything works properly, you can then proceed to permanently glue the brass barrel inside the orange plastic barrel. DIY some plastic spacer rings along the brass barrel to keep it centered within.

Its complete!

Sample Test Fire Results:

PTG: Parallel-To-Ground (Shoulder height, no elevation)
ATG: Angled-To-Ground (Aimed higher, 30 degrees elevation)

Distance is measured at where the dart lands (Average of 6 darts).

Brass Breech Recon (11kg Load Spring)
Ammo: Customized FBR foam + 1.1 gram soft silicone tip weight
PTG = 70 ft
ATG = 90 ft

Note that the test was done indoors and the results are sample estimates for reference (your results may differ depending on materials and mod techniques used).

Important Usage Tips:

- Clips must be loaded only when the breech closed. This is so that the clip feed-lips can "catch" around the brass bolt for a proper fit.

- For smooth dart chambering process, make sure that foam darts used are no more than 7 cm in length.

- The better the foam dart fit in the brass barrel, the better the range results.

- Due to the smaller air volume of the Recon reverse plunger, using longer barrels may cause the foam darts to get stuck as it doesn't have enough power to propel them out. If that occurs, reduce the barrel length and test again.