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DIY LRB mod with one piece barrel spacer

42023 Views 38 Replies 19 Participants Last post by  De Ober
Most of use have heard of a a LRB or long range barrel, and a fair number know what it actually does. For those of you who don't know, a LRB is a barrel that has slight down ward bend in it, so as the BB is propelled out of the barrel, it rides along the top. It improves the range and accuracy by helping to stabilize the BB's backspin and reduce the BB bouncing in the barrel.
Doing a little bit of research, there is a EZ LRB kit by Hunterseeker5 for sale on Shapeways, but it required that you only have one barrel spacer in the first third of the barrel, not the many most of us use for accuracy. Looking at it closely, the main piece is just a wedge with a grove cut in the center for the barrel, I began wondering if you could get the wedge in place to bend the barrel, then pour wax between the inner barrel and outer barrel so the inner barrel will hold its shape, then remove the wedge. This would give you the combined effect of a LRB mod and a wax one piece barrel spacer. So with out further ado, here is my guide for a DIY Long range barrel AND one piece barrel spacer done on a VSR-10 clone, a TSD sd700.

Dowel the same outside diameter as the inside diameter as your outer barrel. If your barrel is tapered (like mine) use a dowel the same diameter as the tip of the barrel.

Paraffin wax, a candle will do, but you will half to remove the wick after it has melted.

Electrical tape

Teflon tape

Barrel spacer that you can drill holes in (I used my the stock one that came in my gun when I first bought it)


Band saw


Belt sander

Stove and pot

*** note these are the tools that I used, there are many different ways to do this mod ***
The first step is to make the wedge that will bend/flex the barrel and holds it while the wax is cooling. The rough shape was cut out with a band saw, using a clamp on strait edge and a tree felling wedge as a guide. This could just be free cut. I apologize for the poor quality pictures. They were the best I could take

My set up

Note that both the dowel and the wedge have to slide in order to cut the wedge shape in the dowel.

The next step is to sand the barrel wedge smooth so that is is strait. I used a belt sander for this.

Now that the wedge has been cut and is now smooth, it is time to cut the groove in it using a router. The outside diameter of a airsoft barrel is usually between 8mm and 9mm because I live where we use English system, so a 5/16'' bit was just slightly undersized, and because it was undersized only the two edges would contact the barrel when it was in use, so I used a square rather than rounded bit. If an undersized bit is used, almost any shape groove can be used. I used square out of convince, it is more important to have the grove in the center of the flat side of the dowel, than have the groove be round.

The depth of the router was set to be slightly over 5/16'' so the barrel would not touch the bottom of the groove, only the edges.

Next the router table was adjusted so that bit was in the center of the guides. I clamped on a second guide so there was no chance of the groove being off. Be sure that the setup here is all 100% square and centered. Any error here will make the barrel bend not perfectly downward.

After the dowel has been run through the router. Be sure to make a pusher stick to push the dowel through, but make sure you hold it down as well. Trust me, its not with loosing a finger over (or the last 1/8 inch of your finger like friend did : /)

Finally trim the edges off the wedge with the groove in it and the wedge is done. Be sure to check the groove is in the center.

Next it is time to prepare the barrel for the bend. The EZ LRB instructions state to place a barrel spacer in the first third of the barrel, but first you need to ensure that it will allow the liquid wax to flow through it it. you can do this by drilling holes in an old barrel spacer.

Next you can wrap electrical tape around the spacer to ensure that it will not be pushed by the wax, and will stay in the place in the barrel that you placed it.

Assemble the barrel and the hop up unit. Be sure any tinkering done to the hop up/barrel are done because your about to cast it in wax. I recommend the dental floss mod with Teflon between the barrel and bucking, a anti blow by ring on the nozzle end of the bucking, an ER-hop, EM nub, and Top dead center mod. Wrap some more electrical tape around the barrel as close to the hop up unit as possible with out interfering with the hop up. The goal is to create a seal so that no wax can get into the hop up. After you have a tight fit, wrap Teflon tape around the electrical tape to get a even tighter seal.

Now put the barrel/hop/spacer up back into the outer barrel, ensuring that everything is in its proper place and screwed down, keeping the barrel end cap off. Use the wedge you just made to add the desired downward flex, testing if needed. Temporarily glue the wedge in place to the outer barrel with a drop of super glue if it slips/moves around.

Melt the wax by placing it in a appropriate container, then placing the container in a pot with an inch or two of water in in. Boil the water on the stove and wait for the wax to melt.

Plug your barrel with a drop of hot glue to ensure no wax gets down your barrel. If wax does enter your barrel, flushing the barrel with boiling water remove it, but it is still better to have done the plug correctly. Carefully pour the wax between the outer and inner barrel, using a small funnel. It is easier to fill the bulk of the barrel with the first pour, and then do a second pour after the first has hardened to get the wax closer to the top of the barrel, keeping the wedge in for both pours. Make sure you pour at least up to the drilled out barrel spacer before the wax hardens, or you risk the holes your drilled clogging up, and having to restart the wax process. Be sure you leave enough room in the top of the barrels for your barrel cap. You will need to drill out the cap wider to accommodate the bend you placed in it.

Wait for the wax to COMPLETELY cool to room temperature before removing the wedge. If the bend in your barrel is off or needs to be adjusted, you can reheat the wax with a heat gun. Remember wax expands when it melts.

An alternative method is to do the wax spacer with out the wedge, then heat the wax with a heat gun and then place the wedge.

Congratulations you have successfully made a long range barrel, AND made a wax one-piece barrel spacer. If you need to remove the barrel, you can hit the outer barrel with a heat gun or hair dryer to melt the of the outside edge of the wax enough to pull the whole barrel and wax spacer out. You can then you can cut off the wax and recast the barrel.

Pictures of targets before and after coming soon.
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Thank you for that... It's really good and interesting way to do a LRB!

I think this should be sticked, as should most tutorials for reference.
Nice job! Can we see some results posted at some point? I would really like to know how well this works!
I will be able to post results tomorrow morning.

my set up that remained constant during the test:

tsd sd700 rifle base
4x32 scope
510mm brass stock inner barrel I believe it is advertized as a 6.05
ER hop
TDC mod
stock chamber, shimmed
dental floss on hop up bucking, barrel side
Teflon between bucking and barrel
anti blow by ring on nozzle end of bucking
angle custom hop up bucking
action army zero trigger and 90 degree piston
angle custom ball bearing spring guide
angle custom 190 spring
custom lathed cylinder head (from stock), sealed with Teflon
stock cylinder

FPS was measured at 623 fps, +/- 15 FPS using a makeshift chronograph, found here:

breeze of about 1/2 to 1 knots was noted during both tests (trust me, I sail competitively at St. Mary's College of Maryland, look them up)

BB's used:
Mad bull sniper grade .43 gram, washed

Rage was 215 feet, +/- 2 feet
Before the LRB: 6 masking tape barrel spacers, all snug.

After the LRB: one piece wax spacer as described.

***note these results are purely subjective owing to all groupings and flyers being eastimated by my eye through the scope and should be treated as such***

***all shots were made from a sitting position***

demonstration of shooting skill: really bad video I made about 4 years ago.

Before the LRB, I was getting groupings of about 5 or 6 inches at 215 feet, with many flyers, approximately 1 in 4. the flyers came in clusters, a group of about 3 or 4 followed by 12 or 16 shots in side the groupings. The flyers would hit low by about 2.5-3 feet and either left or right by the same amount. The BB's were noticeably climbing and falling at that range, a guesstimate of between 6 inches and a foot.

After the LRB, I was getting groupings of about 3 inches at 215 feet. The flyers were reduced to about 1 in 6, that came in groups of 2 or 3. Surprisingly the fliers were hitting dead level, but +/- 2 feet left to right. the BB's were only climbing and falling 4 to 5 inches.

Possible sources of error: wax inside the barrel. some wax dripped inside the barrel, most of it was removed but I am sure some residue remained. Most was cleaned out with boiling water down the barrel, then traditional patches in rubbing alcohol.

My conclusion is that the LRB/ wax spacer greatly improved my accuracy. It was borderline ridicules how much accuracy was gained and achieved, with a stock barrel no less! All of the post LRB tests the BBs were hitting within a 3 inches of the same height. and the barrel pulled the groupings tighter. The wax also reduced the number of flyers as well.

I will be repeating this test with a an angel custom chamber, EM nub, and mad bull 509mm by 6.03 barrel
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This mirrors what I have been seeing with set screws, good to know! Thanks for posting results!
Interesting results, great report!
This mirrors what I have been seeing with set screws, good to know! Thanks for posting results!
What do you mean by mirrors? As in getting the same or opposite results?
If you hold you hand up to a mirror so does your reflection. It means its the same.
I thought you might ment mirror as in oppisite.
Do you just shoot to get the hot glue out?
No I used the cleaning rod that came with my gun.
Great tutorial buddy!

Hey Cheese, what do you mean by using set screws? This also intrigues me.

Should the tip of the barrel be modded, so the bb wont touch coming out of the curved inner barrel or is it not enough of a curve to worry about that?

I agree on the sticky also.
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The bend in this barrel was about 2mm as recomended by cheeseman, so an un modified barrel cap would not work. I drilled mine with a larger hole to accommodate the bend
Ok, I didnt see any mention of it so I felt I had to ask. I may have missed it if it was mentioned.
Drill and tap the outer barrel for set screws, it allows for an adjustable bend.

Also, stickied.
Good point there. Add in to the guide that you had to drill the end cap!
It was already there : ). I may add another section, after hearing how cheese man bends his barrels, it sounds much easier to do and easier to keep strait that the wedge.
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