The Kingman MR Series markers seem to be the latest MilSim craze. A pretty decent marker from the box at a decent price. Some of us like to tinker with our Spyder's to help them along on the performance edge but when you look at one of these markers you might say to yourself, "Where the heck do I start?" They are all of a completely new design for Kingman and at this moment, really have no upgrades available specifically for them besides a few barrel choices. What's more, how the heck could we convert one of these to a low pressure configuration? Plastic and metal vertical foregrips, newly designed trigger frames, no LPC's, straight pressure lines, not even a danged expansion chamber on these babies. Well I'm going to give you my take on converting one of these MR's to a low pressure configuration in this article. Take it, leave it, run with it, deviate it, whichever you should so choose. We can always make a Spyder run much better by changing it's stock configuration or better yet, lowering the operating pressure.

Choosing The Parts

To convert to low pressure, we're of course going to first of all need a high flowing regulator, valve and a spring kit. These are the most important components of an LP conversion and if you choose cheap inferior products, expect a cheap inferior result.

As far as I'm concerned, a vertical regulator is completely out of the question. You'll need to remove the black plastic foregrip handle to do so. Remove the vertical grips and you've taken away part of the beauty of these MR markers. I've seen a few of these markers with the forgrips removed with a vert reg installed and I think they just look terrible compared to before these parts were removed. Please, no offense meant to those of you that have done so. So what we're left with as a choice, is utilizing some sort of horizontal regulator. Specifically a high pressure regulator as Spyder's just don't seem to run that well using low pressure regs even if the running pressure of the marker is relatively the maximum of that particular LP reg. What happens is they are basically starved for pressure especially at high rates of fire. There are 3 choices of good quality HP horizontal regs available that I'm aware of. The HP horizontal Max-flo, HP Palmer's female stabilizer and the HP Doolie. I've chosen the Palmer's female stabe because it's a fantastic product that has stood the trials of time and easily available compared to the others. A mounting bracket is also needed for mounting the Female Palmer's stabilizer to the bottom of the trigger frame. Good news about the new MR Series trigger frames is they have finally moved to the industry standard inline screw pattern rather than the staggered pattern of Kingman's past. This means that you will not need to purchase a mounting adapter to attach the mounting bracket for the stabilizers bracket. Another advantage of the Palmer's stabilizers are that they are exceptionally tolerant of both HPA and C02 propellants and need very little scheduled maintenance. Throw a few drops of paintball oil or tooling oil in the ASA, gas it up, shoot it about 40 shots and you're good to go. No disassembly for cleaning required at all.

Now for a valve choice. There are many high flowing valves available for Spyder's. I'd have to say the most popular are the Maddman Rocket valve, New Designz HP(high performance) valve, AKA Tornado and the 32* Magnaport valve. For my particular project I'm choosing the Maddman Rocket valve. I'll touch on some of the reasons why sporadically later in this article.

A spring kit choice would normally depend on which valve you have chosen. The most popular spring kits for Spyder markers are the 32* spring kit, Shocktech spring kit and the Maddman spring kit. The Maddman and 32* kits are a good choice for valves that require a valve spring. In the case of the MR Series markers, the valve springs in these kits will not fit/work with the valve. The MR's have a valve spring that is longer than normal similar to the one in the Spyder AMG. The bodies of the MR's and AMG are of the long body style unlike the greater percentage of Spyder's available. So your best choice would be the Shocktech kit that supplies 4 different striker springs only. If you're like me and have all of these kits, you can go ga-ga come tuning time. You're pretty much stuck using the stock valve spring in the MR's unless you fabricate one yourself. This is one of the reasons I chose the Rocket valve for my project. It has an integral spring and the dwell duration can be tweeked through the adjustment of the SRP. More on this later.

There are some other parts you will need for this project as well:

First one I will mention is a pressure line. For my particular setup I've chosen to use a 6" steel braided line. You may need a longer line depending on the way you set up your pressure line which will be discussed later. Macroline can be used as well but I think it's inferior to steel braided line. Steel braided line should last you virtually forever where as macroline has a tendency to get brittle with age sometimes cracking or bursting under pressure. The debate of the advantages and disadvantages of both types of pressure line are an old beaten dead horse.

If you choose to utilize the existing VA ASA adapter that came with your MR, you'll need a metric to inch adapter to attach the pressure line to the VA ASA adapter.

Some optional parts you may choose are a quick disconnect and gauge for the regulator. A gauge isn't really necessary but a good component to have if you'd like to know approximately what your running pressure is. I say approximately because, the cheap price you pay for these small gauges, they aren't entirely accurate. A very accurate gauge could cost you well within the $50+ price range. For low pressure purposes you'll want to get a 0-600psi mini or micro gauge. Using a quick disconnect just makes good sense. With all of the tuning involved with an LP setup, you'll find yourself continually taking your marker apart and reassembling it. Without a quick disconnect, you'll find yourself continually removing the line and bracket from the bottom of the trigger frame. This even more difficult task using a horizontal reg mounted to the bottom of the trigger frame. For the modest price of a Q/D, the time saved is well worth it. If you are using macroline, a Q/D will be totally useless.

Other Parts You Might Consider

As of the time of typing this article, there really aren't too many MR Series specific aftermarket products available for these markers.

Barrels that fit the MR2 & MR3 are limited due to the tight fit of the barrel through the front shroud. The J&J ceramic barrel will fit perfectly. I've used the 14" J&J on my Spyder's for years now. It costs little, is super light weight, has a very quiet report, yields great accuracy, basically cleans itself with a few shots if you have ball breakage and modestly priced. What else could you ask for? Since the MR1 has no shroud, you can essentially use any Spyder threaded barrel available with it.

Hoppers and tanks are very plentiful. There are literally tons of them to choose from and the number grows every day. For the MR1, a hopper that has a feed rate of 12bps will suffice but you're going to want something that feeds at a higher rate of fire for the MR2 & MR3 since they are rated at 25bps. For a tank, you can use either HPA or C02. If you're using the stock that came with these markers, you may consider a coiled remote line for comfort. I personally find it a little uncomfortable using the stock with a bottle that can provide a decent amount of shots screwed into the ASA.

Sundragon Products will be releasing a new MR series specific Snapdragon magnetic trigger very soon for the newly designed MR series electronic trigger frames. A much superior feel to it than the stock trigger with little or no slop side-to-side to mention. The smooth magnetic response is another added bonus to its function. We have had a few CCM all metal feedneck adapters to distribute up to the point of typing this article but have not received the larger production run yet. They are just a fantastic add-on for the MR1 & MR2. You'll never need to worry about a cracked plastic feedneck adapter again.

If you look around, there are plenty of cosmetic MilSim additions like M-16 barrel shrouds, folding stocks and the like available at MilSim specific parts dealers. Use an online google search to find those places.

Modifications

I'll bet you thought I'd never get back to the 'LP thang' we were supposed to be implementing here in the first place did you? Since I'm modifying the MR2 here, most all of the things I will discuss may only apply specifically to the MR2 . Some on the other hand, may apply to all. If you plan on following this guide for your marker, you may have to adapt these ideas or conjure your own if you have a different MR marker.

I'm not completely finished with my project at the moment of typing this article and may add entries sporadically to it in the future. There are very few free mods I will be performing at this time for the conversion due to the design and components of this marker in its stock state. As I stated earlier, Kingman certainly didn't seem to make these markers with an LP conversion in mind.

The MR2 is equipped with a delrin ACS bolt, so there's no need to pull a venturi since it has none. Polishing is out of the question as well for obvious reasons. Swoosh-Air modification is within grasp though. I will be using a plastic material rather than wood this time since the bolt is made from delrin. The insert needs to be a bit longer than a conventional bolt since there is a slot in the ACS bolt rather than a habitual hole. The spring in the ACS bolt was extremely tense when I got it so I wanted to break it in a little. What I did was compress the spring and inserted a thin object the same length as the void of the slot when completely compressed to keep it wedged in that position. I let it set like that for a day in that condition. What this does is it slightly fatigues the spring and basically breaks it in a little to loosen up the play.

Since I'm using the Rocket valve, I cut off the extended boss/arm of the reservoir adapter plug(pt#254) with a dremel cutting disk. See the reference photograph below. The boss is there to hold the spring in place, opposite the end of the valve pin. Since the Rocket valve has its own spring, this boss is not needed. Why do such a thing you say, good question? If you remove the screw-in VA under the body, you'll notice that this arm actually obstructs the flow of pressure going to the valve. Free flowing pressure is what we want in a low pressure application, so removing this obstacle will make the LP MR flow much easier. This is only recommended if you're using the Rocket valve for obvious reasons. The cylinder is actually removable from the block so if you change your mind and decide you'd like to use a different valve, you can always purchase a replacement part from Kingman.

There is a bit more length or area in the front portion of the longer than normal body of the MR's, so the volume of pressure ready to feed the valve isn't too shabby. An LPC has been added to the shorter Spyder bodies to store an extra volume of pressure to feed the valve that's especially an advantage at high rates of fire. Since LP markers thrive on passing a larger volume of pressure at lower pressures, we want to create as much reserve pressure available as possible. The next mod will only add a modest bit of reserve volume, but every little bit helps the end result as a whole. What I've done to add a bit more volume is to drill the hole in the vertical hose adapter(#253) slightly larger. The center hole in the stock screw-in adapter is approximately 5/16" in diameter. You should be able to safely expand the center hole to 7/16" and leave ample thickness and strength in the aluminum material for the o-ring slot. I had a 27/64" bit handy which is a hair short of 7/16", so I used that and expanded the hole to a 1 1/2" depth. If you drill the hole too deep, you will drill out the threads at the bottom of the adapter for the hose so be careful. I wrapped a piece of masking tape around the drill bit at a 1 1/2" length so I'd know exactly what point to stop drilling. After drilling, I sanded the internal surface smooth and deburred the top edge of the hole. Afterwards, everything was cleaned with soapy water to remove any metal and grit particle residue.

I've made another VA related discovery that will add pressure volume but it's not as simple a mod as the previously mentioned. I was rustling around in my spare parts box and ran across a couple of old stock Kingman expansion chambers. Looking on the inside of them I noticed there was a lot more open space inside of them than the vertical hose adapters supplied with the MR's. Looking down the end of the black plastic foregrip handle, I noticed that even though the handle is on a forward angle, the hole going through the grip is perfectly in a  90* angle from the body. The expansion chambers screw in to the MR VA's just fine. The only problem is that the expansion chambers will not fit into the hole in the handle. I took a quick trip to my machinist and had him shave the excess outside diameter material of the expansion chamber down to 15/16" which is slightly smaller a diameter than the hole in the grip. It's color is raw silver but that doesn't really matter since it will be encased by the black plastic grip anyways. After he was finished removing the material I discovered I could have had him mill even more material from the expansion chamber that would have lightened the part even more. It was free so I couldn't complain and I got the results I was aiming for. After getting it home, I drilled the smaller inlet hole on the line end of the expansion chamber out to 17/64" to open up the flow of pressure coming from the line. This left a small ledge where the line would be screwed into in case I wanted to install one of the gold colored filters and o-ring seen in bottom line ASA's that prevent liquid C02 from getting into markers. If I were to manually remove the outer material from one of these expansion chambers, I would find a way to chuck it into a drill and while turning it, use a rough file to remove the excess aluminum. After removing most all the material, going to a fine file then to sandpaper to smooth it. Installing one of these expansion chambers will add pressure volume equal to or greater than an LPC. Pictured below is, left: an expansion chamber similar to the one I had milled, center: the milled expansion chamber, right: the stock vertical hose adapter that is supplied with the MR2 marker.

When attaching the new 1/8"npt threaded line from the regulator to the metric threaded vertical hose adapter, you'll need to use a metric to inch adapter to couple the two together. Simply screw the male end of the metric adapter into the bottom of the vertical hose adapter. Then screw the line into the female end of the metric adapter making sure to use teflon tape on the line threads to ensure a good seal. The male end of the metric adapter has an o-ring seal on it, so teflon tape is not required on those threads. After purchasing the stainless line for mine, I thought of an alternative manner to attach the line to eliminate the vertical hose adapter. You can purchase a C/A to 1/8"NPT adapter that are used on remote lines and screw that directly into the VA of the marker. Then screw the line directly into the C/A to 1/8"NPT adapter making sure to use teflon tape on the line threads. The length of the line will be longer than the 6" I mentioned previuosly if you choose to attach the stainless line in this manner. Both setups mentioned here are shown in the photograph below as reference.

If you're using the Rocket valve, you might consider blocking off the striker exhaust port in the bottom of the marker. If you do this with any other valve, it will hinder the recocking properties of the striker because it creates a vacuum between the valve seal and the striker seal. This is negated when using the Rocket valve because it has no rear seal. There's a little information concerning this mod in the LP free mods article in the SPPS tech section.

 More mods may be added to this portion of the article in the future.

Putting It All Together

Now it's time to put this bad boy together. I will be specifically outlining the way my personal LP MR is constructed here. Of course, all are welcome to deviate this formula at will. This is just a guideline that may get your brain ticking into the LP mode for your own MR.

Below are the products I've chosen for this MR LP conversion:

• Palmer's Female Stabilizer
• Palmer's Mounting Rings
• Maddman Rocket Valve
• SPPS Dragonfly Striker
• SPPS SnapdragonMR Magno-trigger
• CCM MR Series Feedneck Adapter
• CCM Imp/Shocker/Ion Clamping Feedneck
• 14" J&J Ceramic Barrel
• CP 0-600PSI Mini Gauge
• 6" Stainless Steel Line w/Black Shrink Tubing
• Quick Disconnect 
• Metric Adapter
• Hogue Handall Grip Sleeve
• Coiled Remote Line

Teardown

We can begin by basically tearing the whole marker down. Remove the drop from the bottom of the trigger frame. Remove the screws to loosen the black plastic foregrip handle. Once that's loose, you can pull it down to get at the end of the line attached to the vertical hose adapter. Untorque the line then unscew it the rest of the way by hand. You can now remove the black plastic foregrip handle as well. Remove the trigger frame. Remove the feedneck and don't forget to remove the small rubber fang detent and put it somewhere safe so it doesn't get lost. When I do these types of teardowns, I have a small ziplock bag handy to put all of the fasteners and small parts into so they don't get misplaced or lost. Next remove the quick strip pin then the back cap and all of the internals. The internals are a bit tough to remove since there is no external cocking mechanism. Since you have the trigger frame removed, pull back on the t-handle to move the internals back then use something to push the striker back the rest of the way through the slot in the bottom of the body. Remove the front block, valve spring, valve pin and cup seal assembly. Now let's remove the valve. Remove the brass screw from the bottom of the body. Using a plastic or wooden object such as a pencil, push the valve out towards the front of the marker through the bottom tube from the back of the marker. I have a 1/4" diameter by 9" long dowel rod that I use specifically for this task.

HEY! Lookie here.....Just noticed that the new MR stock Kingman valve bodies are blocked off at the bottom where the valve screw goes. No more straight through holes. Looks exactly the same way that New Designz has been making their valves for years now. Proof positive that innovation is contagious.