In this guide I will go over what parts I used to upgrade my LCT VSS into a top-tier DMR and also tips and tricks to help you decide what parts you want to use in your own build.

Update Feb. 2021: Thanks to all who have read our guide! Our website has grown a bit since this was first posted a few years ago. I’m still using the BTC Chimera mosfet I mention in this guide, but we also carry a lot of other mosfets and wiring materials in our shop here. We also do airsoft 3D printing and have just made a new custom rail system for LCT AS VAL and VSS’s which you can see here. Thanks again!

DMR Build Overview

My VSS is my most heavily upgraded gun. Since this is a DMR build, the focus has been on range and trigger response. Range is most important because being able to reach farther enemies is the main advantage of using a DMR, and trigger response to make up for the weakness of being restricted to semi auto only. DMR builds are typically on the expensive side, since their higher stress and performance requirements necessitate buying premium products, but I also note where some more budget friendly options are possible.

Parts List

Below are all the parts and their costs for my DMR build. I also noted the importance of each upgrade. The most important parts are things that anyone building a DMR should look into. Medium importance are things that don't need to be upgraded, but can be for personal choice or extra performance. Low importance are things that are fine to leave as stock or are cosmetic.

Stock Internals Overview

The internals for the LCT VSS are very high quality. This also goes for their AS VAL and SR-3M which use the same gearbox. Polycarbonate piston with full steel piston rack, aluminum piston head with bearings, aluminum double o-ring cylinder head, POM nozzle with o-ring, steel spring guide with bearings, all in LCT’s 9mm bearing gearbox.

Motor & Gears

In conjunction with the battery, the motor and gears account for most of the fire rate and trigger response. At first, I left the stock gears and only upgraded the motor to a Lonex A2. This is a decent option for those with a more limited budget. Compared to the following combo, this option is 20-30% the cost, with 80% the performance.

The current combo I’m using is an ASG U-18000 motor with Siegetek 10:1 SSG gears. While much more expensive, this combo is for those who want the best trigger response for their high end DMR build. I took the idea of pairing a 22TPA motor with 13:1 gears and stepped it up a notch. The ASG 18k is 28 TPA and has extremely high torque, in exchange for a very slow top speed. This slow speed is offset by using low ratio gears, and there’s none lower than Siegetek’s 10.44:1 Single Sector Gearset. Pairing these together gives incredible trigger response. The build quality of the ASG motors and Siegetek gears is superb, and gives peace of mind that nothing will break.

The unique motor cage of the VSS (and the other guns with this same gearbox) doesn’t allow the pinion gear of the motor to fully meet the bevel gear, even when adjusted all the way up. This makes it nearly impossible for a “perfect” shim job. I’ve tried to dremel material off of the top of the inside of the motor cage, where the top of the motor touches. I haven’t had much success, though, because it’s hard to get a dremel in the small corners. In the end, I’ve just compromised to having a slightly noisy gearbox.

For the Siegeteks, the anti-reversal latch needs to be sanded down slightly (.5-1mm). This is mentioned in the official instructions for the gears. I did try to get away without it, and had catastrophic malfunctions. Filing it down according to the instructions fixed everything.

Electrical

For a mosfet, I went with the best: BTC Chimera V3. With many customizable settings, microswitch trigger, and cycle detection, the Chimera is great for handling the very fast trigger pulls and cycle rates. Options for motor braking, pre-cocking, and semi-only settings allow for tuning your DMR to whatever you like. Good luck finding one for sale.

Update Feb. 2021: There have been several new ETUs that have come to market since writing this guide, like the Perun Optical and the Gate Titan and Aster. I haven’t personally tried these in my VSS yet, but if you are interested we have some in stock over at our electronics store.

Getting the Chimera to fit in the VSS is slightly challenging. Good news is that it fits in the gearbox perfectly with no filing required. Bad news is that the fire selector won’t work and it’s hard getting the mosfet to fit in the suppressor. Because the VSS has a unique fire selector, it’s no surprise that it will not work with the Chimera, which is based off of standard V3 gearboxes. For a DMR build, that’s not a problem, since most will choose to have their gun be semi-only (as it should be). What is not immediately apparent, is that the microswitch on the Chimera which is usually for the selector plate is exactly where the gearbox is secured in the receiver. That means that the microswitch on the Chimera will break off when you put the gearbox in the gun, permanently damaging the Chimera. It will never have two firing modes again. If you intend for your VSS to always be a DMR, like I have, it’s not a huge deal apart from resale value. If you might want to be able to switch firing modes in the future, get a different mosfet. The Chimera comes with 16 gauge wiring and deans connectors, typical for most upgraded guns for less electrical resistance.

The wires from the motor and trigger board run where the stock wiring went. It hardly fits. Be careful putting on the handguard and suppressor or the wires can get stripped. Also, I recommend taping and securing the wires and mosfet onto the inner barrel itself. Since the suppressor twists on, and the mosfet and battery hardly fit anyways, it sometimes pulls and twists the mosfet and battery with it. The battery and mosfet wires can get unplugged while this happens.

The VSS is very limited to which batteries will fit. To get this most out of your gun, you need an 11.1 lipo. Only “Tri-cell” or “3 Cell” batteries will fit in the suppressor, where the battery is separated into three long sections. The one I use is an 1800mah 20C 11.1V Lipo from Hobby King. This battery is pretty much as long and thick as the battery can get while still fitting inside the suppressor. Some people use much stronger batteries in conventional upgraded gun builds, but unless you want to figure out an external battery solution, this is as good as you can get.

Barrel, Hop-Up, & BBs

Perhaps the most important part of a DMR build, the barrel and hop up are what gives you the range and accuracy to hit distant targets. For the barrel, I have a Prometheus Steel 6.03 barrel in 407mm length. Prometheus doesn’t offer a length which exactly matches the stock barrel’s length. The next longer one would stick out past the suppressor, but the next shorter is still long enough to reach the stabilizing ring at the end of the inside of the suppressor.

For the hop-up, I use the current best hop-up you can buy: R-Hop. While you can definitely make your own R-hop, I decided to have a professional install mine because a) I haven’t done it before myself, and b) because I want it to be perfectly done to get the most out of my DMR build. The R-hop and M-nub for my VSS was done by Sherlock at the airsoft subreddit.

I’ve used a lot of different bb’s since I built my VSS, including Valken, Elite Force, HPA, Bioval, and EMG from .25 to .40g. The LCT VSS magazines seem a little picky about which bbs will consistently feed. Bioval would not feed a single bb. Valken .25, .28, and .32 all fed no problem, however my last batch of Valken .32’s seem to cause jams and break my gun. The Valken .30’s would also not feed at all. For when I had to borrow bb’s, Elite Force .25 and HPA .30 seemed to work fine, but I don’t have more than a game of experience with them for conclusive data. The most recent I’ve used is EMG’s .40 Bio. These fed 100% every shot and gave me the most range out of any (but this was also the first I’ve used heavier than .32). With the Prommy barrel and R-hop, the .40 bbs would accurately hit 250 ft, and possibly farther, but I didn’t have any targets farther than that.

Compression Parts

Apart from the spring, the stock compression parts hardly need any upgrading. LCT’s internals are very high quality. To reach higher FPS expected of DMR’s, though, you will need to upgrade the spring. Using a Systema M140, I’ve been right under the FPS limit of 450fps/1.85J for two years without any drop in performance.

I’ve also added a ⅛” V3 Sorbo with the Neoprene buffer for 3 reasons:

1. Improve Angle of Engagement (AoE) - They say correcting AoE is a must, but I’ve been using the stock piston and gears without the sorbo for 2 years without any problems or signs of wear, even using an M140 spring. Nevertheless, the ⅛” is the perfect thickness for optimal AoE. The 2nd tooth should be completely removed and the 3rd tooth should be shaved down about halfway.

2. Sound deadening - I thought it would make the sound slightly softer, but really it’s not all that much different.

3. FPS Drop - perhaps actually a downside to adding a sorbo, I was actually getting dangerously close to the fps limit at times. I thought adding a sorbo would drop my fps just enough to where I wouldn’t be nervous about passing chrono or not. Turns out that I didn’t lose any fps after installing the sorbo, to my surprise. Perhaps due to the strong M140 spring, since I did have an fps drop in my F2000 after adding a sorbo.

Lastly, I upgraded the nozzle to a Hawk Arms Aluminum V3 Short Nozzle with O-Ring. There’s really no performance benefit to this, I just wanted a metal one. The rest of the compression parts can be left as-is, even for upgrading to a DMR. Nearly all the upgraded compression parts you’d normally do already come stock in the gearbox.

Externals

The external upgrades have some utility but are mostly just for looks (welcome to airsoft).

The sling is (supposedly) a genuine Cold War era soviet sling from eBay for around $30. It’s doesn’t quickly attach and detach like regular slings, so it pretty much stays on all the time. It comes in handy when walking to and from respawn, since the gun is quite heavy. Definitely would recommend.

The scope is a Matrix PSO from Evike. You may have heard that replica PSO scopes are bad, and that is true. While it looks great on the gun, it’s next to useless for aiming. The reticle just doesn’t point to where the bbs go. There are adjustment knobs, but they don’t adjust nearly enough, if at all. The 4x zoom is helpful for seeing distant targets, and the scope can still be used as just that - a zoom. Ignore the misaligned reticle and the zoom makes it easier to see where your distant shots are pointed, although judging distance can be difficult. Also, this is an illuminated scope, but the bulb on the bottom must be removed in order for the scope to fit on the VSS.

The rail mount is the official LCT rail mount for attaching to the suppressor. I’ve attached a short bipod. For moments when you have a good spot behind cover and you need accurate long range shooting, the bipod takes care of holding the gun steady.

Update Feb. 2021: We’ve designed our own custom rail system for the LCT AS VAL and VSS, which you can check out here!

Lastly, the cheek pad is a regular SVD cheek pad from Evike. It originally had hardware for mounting onto an SVD. Remove that so just the pad is left, add some velco, and you have an easily removable cheek pad for your VSS. Some sort of pad is necessary if you want to look down the scope. The scope is just too high to be used with your cheek on the wood stock.

Conclusion

The LCT VSS is a great gun to be built into a DMR. It has the looks and the hardware to perform - and also gets jealous stares while doing it. The mags are small and the gun is heavy, but if you’re looking for a unique airsoft gun, the VSS is a fantastic choice.