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.


  1. Hey SG- Can I assume correctly that the reciever and bolt can be cut down so a clip can be loaded when it's open, just as you did with the longshot breech?

  2. Matt,

    If you are referring to the alternative "quarter-pipe" method of cutting the barrel and bolt sections, like this:

    Yes, that can be done for the Recon too.

    The brass breech mod for the Recon is basically the same as for the Longshot, just with shorter dimensions. :)

  3. Cool, thanks. I was going to do this to my alpha-trooper, i'll let you know how it goes and if measurements need to be different. The recon plunger tube and the AT's plunger tube are about the same size though, i'm expecting to only have to mess with the barrel length of brass. we'll see...

    Also, I'm about to make your version of the angel breech with the quarter pipe design. I wanted to leave the bolt section as a half-pipe instead of a quarter pipe since i'll be using an AR-15 spring and i'll want the greater surface area to attach the original bolt piece. I know you said in the guide that the bolt side had to be trimmed to a quarter as well, but if the bolt is pulled back then it shouldn't interfere with the insertion of clip, correct?

    Thanks in advance- Matt

  4. Matt,

    Well, if you want to do the "quarter-pipe" design, then both the bolt and barrel need to be cut in the same way.

    This is because when the bolt is pulled back to open the breech, the guide on the bolt will be positioned directly over the clip feed section, so if its not a quarter pipe, the clip will still get stuck.

  5. so does the length of the brass have to be different if this is to be done to the raider

  6. attackthekid,

    The brass section measurements could differ slightly for the other reverse plunger blasters, so modders will need to test and make the necessary adjustments.

  7. When adding the tightening rings onto the barrel, is there a risk of accidentally cutting the pipe? I was worried about this and it took me a few tries to get it right because the dart kept falling out of the front. How can you reduce the risk?

  8. Naturalman_7,

    Well, the trick to making tightening rings in the brass barrel is to only do shallow rotational cuts... stop cutting once you see the circular dents and the narrower diameter rings form inside the brass tube. Its all about trial and error.

    If your foam darts are still loose even with tightening rings made in the brass barrel, then you'll have to change the size of the brass barrel or the size of the foam darts. :)

  9. My last question is what type of pad works best? I've tried several and haven't been able to find a good one yet. Instead of buying all the pads and trying them all, is there a type of pad that works better? Gripper pads? Anti-slip, felt, bumper? I've tried some brands but most were too thick.

  10. Unknown,

    Any soft padding that can compress flat easily can work. Like i've mentioned, you have to test and see what works.

    The common foam bumper material that hardware stores sell for cushioning furniture and table edges can be used.

    Also try craft foam, they can be found easily at most art and craft shops.

    If the padding is too thick, then just trim it thinner.

  11. Thanks for your help.

    Which material do you think works best?

  12. Unknown,

    Both foam bumper and craft foam work as well, they are usually made of similiar foam materials.

  13. Do you need to keep the barrel attachment from the recon on? And where on the new brass barrel did you wrap it with tape?

  14. SG Nerf,

    I can't seem to do the barrel right. When I wrap the brass barrel with tape either the brass bolt hits it, the friction between the brass pushes the barrel out of the front, or when I try to position the brass barrel into the old one the tape just gets pushed out of the way. I'm not sure how to properly complete this part.

  15. Unknown,

    Its not necessary to use the front barrel attachment, the brass barrel lengths i use for Recons are usually less than 6 inches, which just fits within the main unit, 'cos if the barrel is any longer the performance tends to decrease and the foam darts sometimes even just get stuck due to lack of plunger air volume and power.

  16. Naturalman_7,

    Seems the tape you are using is abit weak or loose and slips off too easily, try using better quality electrical tape.

    You need to keep testing various thickness of tape wrap around the brass barrel until it wedges securely inside the orange barrel.

  17. SG Nerf,

    Is there a secret I don't know? I bought 3M Scotch 33+ electrical tape and I still can't seem to be able to keep the barrel in place. Another thing is that there isn't a very large area to wrap the tape around. Any help would be appreciated.

  18. Naturalman_7,

    Just wrap the electrical tape in layers around the front section of the brass barrel and secure it properly. It requires some adjustment to get the fit just right.

  19. i had a better idea for the breech. instead of inking three layers by hollowing out the punger. just sink the 1/2 and 17/32 width brass all the way into the plunger. by doing this the seal is much stronger and the greater shrink from one volume to another gives it more pressure. i would like your ideas on this

  20. crakdice,

    That can be done too, but you have to make sure the alignment of the bolt and barrel are 100% perfectly aligned, as there would be no more extra tolerance of any variations in alignments (just a slight difference will restrict the movement of the bolt).

    That's one of the reasons why modders do the brass breech with 2 layers of spacing, so that the priming movement is smoother.

  21. I am confused as to where the piece from step 3 is supposed to go

  22. Unknown,

    The brass tube section (with half-pipe and tightening rings) in Step 3 is the barrel for the brass breech, it is installed inside the existing plastic barrel. :)

  23. My darts have trouble feeding and most of the time when I shoot the gun I get a slurping sound and the dart gets stuck in the barrel.

  24. crakdice,

    Chambering issues could be due to your breech system not properly aligned with the clip, check and re-align if required. Shortening the foam darts slightly (ie. to 6cm length) could help too.

    The stuck dart issue could be due to the breech system not being fully air tight, there could be some air leaks at certain sections, so you need to check the breech to barrel seal. It must have a 100% air seal.

    Alternatively, it could also just be the barrel being too long and the foam dart getting stuck inside. 

    As mentioned in my guide, the Recon's reverse plunger air volume is small so it naturally doesn't have enough power to propel the foam dart through longer barrels (compared to other blasters with larger plunger volumes like the Longshot).

    From my experience for a brass breeched Recon with 11kg load spring, i only use a 6" length brass barrel. If the barrel is longer, the foam darts would tend to get stuck halfway or fire out with reduced range.

    Note that if you install springs with less strength, then you might have to use even shorter barrels due to the reduced power. Just try out various barrel lengths to find the optimal setup.

  25. What would be the total cost of this mod?

    1. Nerf Modder,

      Well, just the brass tubes for this mod costs around SGD$20+... not including the additional custom aftermarket spring, dremel, epoxy glue and various other tools to do the mod.

  26. Hey SG Nerf, can the same dimensions be used for the alpha trooper? And EXACTLY which shop did u purchase the brass from? Thank you!

    1. H3LL bOy,

      The same modding method applies to the Alpha Trooper, but the tube lengths might be slightly different, so you can take reference from the guide but will need to also re-check the fit and adjust if needed.

      I get my brass tubes from NTC Engineering Hobbies at Fook Hai Building in Singapore.

  27. Just curious, if I were to apply this breech to a Raider, should I use the same measurements and dimensions? Also, does a properly done brass breech achieve about the same performance as an aftermarket plunger such as the OMW kits?

    1. Brian Lin,

      You could use the Recon measurements here as a guide.. but do re-measure the Raider internals to confirm and tweak the parts dimensions if necessary.

      A properly made breech with 100% bolt to barrel seal should achieve better ranges than a stock breech (with equivalent mods).

      But as mentioned in the guide, reverse plunger blasters have such small plunger volumes that they naturally don't have enough power to propel the foam darts through longer barrels anyways, so only the shorter barrel lengths can be used, which limit the overall range improvements.

      100% bolt to barrel seal breeches work best with the larger plunger volume blasters.

      The current OMW kits are basically replicated versions of the stock breech design (but made in polycarbonate), as there is no 100% seal between the bolt and barrel, the performance improvements would be based upon that of a stock breech system.

  28. I've got everything complete, but I have a pretty good-sized problem I can't seem to overcome - the lower portion bolt grabs onto the next dart in the mag and tears it to shreds. I've been looking at the problem and various solutions (lipped the underside of the bolt, positioning, etc) and I can't come up with a solution that works. How did you manage to surmount this problem?

    1. legendinmymind,

      Hmmm... i've not encountered that issue before, maybe the position of your brass breech is abit too low or angled in such a way that it grabs too much of the next foam dart while chambering the first foam dart.

      I guess you just have to check the alignment of the brass breech. During the chambering process, it should only skim over the next foam dart slightly, not grab or snag it.

  29. Can i use aluminium tubing instead?
    like that?

    1. HowToModify,

      Well, so far i've not found a set of aluminium tubing that could nest perfectly within each other to create the necessary air seal... only the series of K&S brand brass tubes (as mentioned in my mod guide) have the perfect "telescopic" nesting and 100% air seal characteristics.

      I guess you could try various types of aluminium tubing and test to see if they can nest and get a complete air seal, do post up your results if you manage to find suitable versions.

  30. will there be alot of dead space from the plunger to the dart after this mod? will this effect the range?

    1. HowToModify,

      There will naturally be abit more deadspace due to the foam dart being pushed forwards into the barrel (instead of backwards into the bolt). The additional deadspace probably affects overall ranges slightly, but so far it seems rather minor from my tests.

    2. so the bolt pushes the dart into the bolt receiver?

      Where is the bolt receiver placed? at the barrel attachment adapter?

    3. HowToModify,

      In this breech design, the brass bolt pushes the foam dart into the brass barrel (at the section with the tightening rings), then both the brass bolt and barrel connect together to form a 100% air-tight seal.

      The brass bolt's half-pipe slides over the brass barrel's bolt receiver half-pipe, this is designed to keep both parts aligned together during the chambering process.

  31. Is the bolt receiver place at where the dart was at? does the tubing of the bolt receiver come out of the blaster?
    Thanks So Much

    1. HowToModify,

      Well, the brass barrel's bolt receiver section basically helps guide the brass bolt, it actually slides into the brass bolt assembly when the breech is closed.

      Check out the Longshot "Brass Breech" guide to see how it works, there is a photo showing the brass barrel and brass bolt assembly outside of the casing, that should help to give you a better idea of their relative positions.

  32. im using stefans in mine, and even with the tightinging rings, (mispelled alot i know lol) the stefans seem to saty in the barrel, but if u really shake the gun hard or blow in the clip loading mechanism, the dart just comes out. should it be tighter? as in cant use it as a blowgun tight? or does it have to be kinda lose, where u can shake the dart out if u rlly tried?

    1. Anonymous,

      That should be an okay fit, the setup shouldn't be too tight or else the stefans may end up getting stuck instead, 'cos such blasters might not have enough power to overcome the added resistance.

  33. Hey sg, is it possible for you to do this EXACT method, except on a retaliator?

    1. Anonymous,

      Yes, this brass breech design can be done on the Retaliator too, you just have to tweak the measurements to fit it.

  34. Like how would I tweak it?

    1. Anonymous,

      Just adjust the brass bolt assembly measurements according to the Retaliator bolt length... the key is simply to make sure that both the brass bolt and barrel connect to each other properly.

      If you are unsure of the process, i would advise you to follow this guide and do a brass breech mod on a Recon first, before modding a Retaliator.

  35. Can you do a retaliator mod guide?

    1. Anonymous,

      You can refer to my Retaliator Mod Guide here:

      If you are referring to a brass breech mod guide for the Retaliator, i've no plans to make one as it is basically the same process as brass breeching a Recon (it'll just be a repeat of the steps).

      As mentioned in my previous comments, modders just need to adjust the brass measurements accordingly to fit the Retaliator.

  36. Hey SG, I was wondering if I could make the receiver shorter so it all fits inside the main retaliator unit without having to use the barrel extension. Would that cause any problems?

    1. Anonymous,

      If you are referring to making the brass barrel shorter to fit within the main blaster unit, its possible but then you will end up with a really short brass barrel.

      With a shorter brass barrel, the ranges will be reduced as the foam dart/stefan leaves the barrel too early, so the air pressure is wasted before it achieves optimal velocity.

      What i usually do nowadays is to just use a length of 13mm SingaPlastics PVC pipe and coupler (or similar suitable pipe material) to sleeve over the protruding brass barrel, that will cover and help to stabilize it too.

      In that way, you can still have a brass barrel with optimal length (along with a stable barrel cover), yet not need to use the entire front barrel attachment.

  37. Hey there!

    I'm planning on doing this to my Retaliator, and noticed you used 9/16's for the main barrel. I'm guessing your using stefans for this? Or does this work well with stock streamlines too?

    1. iModify,

      Nowadays i use only calibrated stefans, but 9/16" brass barrels can also use stock streamlines too (though their performance wouldn't be as optimal), you just need to add tightening rings in the brass barrel to help hold them in place before firing.

  38. Hi, I've got a quick question before I attempt to do this on my Retaliator:

    Assuming that darts have a width between 1/2" and 17/32", wouldn't the larger width bolt damage darts under the currently fed dart? The 19/32" pipe seems like it would dig into the next dart about 1.5mm from its OD. I wouldn't want to run into the same problem as legendinmymind from above.

    1. Anonymous,

      If the brass bolt and brass barrel are made properly and 100% aligned with each other, the 0.014" difference at the bottom lip (that's only 0.3556mm, even less than half of a millimeter) will not cause any issues as the next foam dart in line is soft enough to allow the bolt to slide nicely over it.

      Once you've built and tested it out, then you'll experience how design works. :)

      Btw, the specification label of the brass tubes (ie. 1/2", 17/32", 9/16", 19/32" etc) refer to their outer diameter. To find out their actual inner diameter, just take the outer diameter and subtract the total wall thickness (in this case 0.014" x 2 = 0.028").

  39. Hello Mr SgNerf!

    I'd like to first say i love your site and its really informative!

    I'd like to know how best to ensure accuracy with stock elite darts..

    I'm intending to brass breech a retaliator. Would the recommended lengths in your retaliator guide be optimal for elite darts?

    1. boingboingboing,

      Thanks for the nice feedback!

      Unfortunately there isn't much you can do to ensure accuracy for Elite foam darts, other than to always only use new ones, and discard those that are bent or worn out.

      You can follow the brass breech methods in this guide, but note that the plunger system of the Retaliator is different from the Recon, so you will need to adjust the measurements of the brass bolt assembly tubes abit shorter to adapt to the new design (adjust enough and keep testing to match the brass bolt travel to the new Elite internals design).

      Elite foam darts are similar length to normal streamline foam darts, so the breech gap can be the same.

  40. First off let me say that I find your awesome website to be a fantastic source of information and inspiration. Thank you very much for sharing your knowledge and expertise in air guns and all things Nerf!

    I am currently planning to crack open my LongStrike to install a OMW Massacre kit and wanted to do a brass breech as you've shown here since it essentially shares the same internals as the Recon. I have one question though, why are the 9/16" & 17/32" pieces so short and all the way at the far end of the bolt?

    I thought the objective of this build was to have a 100% air-tight seal with the barrel? Would it not be better to cut out a space for the barrel's half-pipe in these two pieces and have them interlock around the 1/2" pipe when you've chambered a dart?

    Or is there a specific reason they are only 2 & 3cm long and at the joint with the original plastic bold end-piece? Please let me know if these are for anything other than to support this joining of original plastic and the brass breech.

    Thanks in advance for your help!!

    1. Anonymous,

      Yes, you can also cut the 9/16" and 17/32" spacer pieces to the exact shapes so that they fill up the empty gaps within the bolt, but yet still allow the 9/16" brass barrel half pipe to slide into the bolt... its just more work and patience to cut them to those specific shapes. :)

      I've not tried doing that design though (abit lazy to do all the extra cutting), so no idea if there is any noticeable improvement in performance if the bottom layers of gaps are filled in.

      Maybe you can try it out and see if it helps, do post an update if its worth doing the extra cutting and shaping of the spacer pieces. :)

    2. Okay, will do. I tend to over think things and dont mind extra work if its worth it. You know the saying "If its worth screwing up, do it big time and they will never ask you to do it again". (Ha ha)

      I'm sourcing the brass now and hope to have this complete by the weekend. I'll make up the breech both ways and try them out. Will let you know if there's an improvement with the "jigsaw" method or not.

      Thanks for your help!!

  41. Hey quick question, sorry if you already answered this, but would it work for me to mod a retaliator (take out the air restricter, and add a different spring) and then brass breech it the whole way into the barrel extension? (The barrel extension would be permanent).

    1. Anonymous,

      Yes, that can be done... but note that due to the small air volume of the Recon's reverse plunger system, the brass barrel itself can't be too long or else the foam darts may not be able to be fired out (even if using stronger springs).

    2. Ok cool, and sorry, one more question, I had wanted to add the Barrel extension on the Modded Retaliator so that I could add attachments and possibly integrate another smaller pistol under the barrel. But as you know barrel extensions usually slow down nerf darts. So would there be anything I could do to the barrel extensions' inside to not slow down a dart? (I have heard of putting small and skinny pvc pipe on the inside but wasn't sure if that would work). That way I could keep the extension on without hindering the blaster's modded performance.

      Thanks so much for your time!!!!

    3. Anonymous,

      Putting a narrow pipe in the barrel extension will usually slow down the shot due to friction, as it bumps around against the pipe walls... the shots from such blasters are not sufficiently powerful enough to overcome narrow barrels.

      You could try removing the inner faux barrel tube (or use a wider inner tube) so that there is lower chance/less contact time for the foam darts or stefans to bump against them.