MAGPUL PTS MASADA ACR Response Up Custom

It's been quite a while since the disassembly of the PTS Masada, but let's get started with the customization.

It's finished by the time of writing, but it was quite a struggle.

I almost didn't want to do it anymore, but I somehow managed to finish it.

This time too, it will be a standard high-response, moderately high-cycle, long-lasting hop-up system.

All things considered, this seems to be the most stable and easiest to use.

Selection and procurement of custom parts

As usual, the menu will focus on motors and drivetrain components.

In addition to the above, I think I used 1.25 sq Teflon and silicone wiring, Bellhammer for fuse installation, and GAW extreme pressure grease (I've forgotten some details).

Although some features ultimately weren't used, I'll include the final specifications at the end. Please bear with me.

Preparing the gearbox

Processing the gearbox casing

First, as usual, we'll start by polishing the sliding parts of the gearbox. We'll polish the red areas with #1000 grit sandpaper.

I round the corners of the window at the front of the gearbox. I use a rotary tool to grind down the front, back, and all four corners. I don't use particularly stiff springs, so this is more of a superstition for me.

Here is the result after processing.

The corner of the gearbox window.

Furthermore, since we'll be using thicker wiring and adding FETs this time, the number of signal lines will increase, so we'll enlarge the holes for routing the wires.

I eventually drilled all the way through the hole on the left side.

This completes the outer casing of the gearbox for now.

Switch replacement and signal wire installation

First, compare the original switch with the Omron switch. The top one is Omron, and the bottom one is original. The red part is unnecessary, so cut it off.

The terminals have cuts in them, so you can grab them with pliers and twist them to snap them off.

Next, pre-solder the switch and signal wires.

Finally, place the signal wires on the terminals and apply a soldering iron to attach them, and you're done. I also added heat shrink tubing.

This completes the switch for now.

By the way, any thin wire will do.

Compare the replacement parts inside the gearbox.

We'll compare the replacement parts inside the gearbox to determine whether they're usable or not.

First, the cylinder. Even the best parts will always have burrs on the back of the red line, so use a round file to remove them. Be careful not to damage the inside.

Diamond file set
These diamond files offer great value for money. The round files, in particular, are very useful. The 5-piece set is highly recommended.

Next, let's look at the tappet plate. The top one is from Laylax and the bottom one is the original. You have to be careful when checking the tappet, otherwise the nozzle position can change slightly, or the shape of the fins can change the amount of nozzle retraction and timing, and in the worst case, it may stop feeding altogether.

From what I can see, the rounded edges at the base of the wings look good. The perpendicularity of the tip also seems fine. The nozzle position might change slightly, but that shouldn't be a problem once it's fitted.

Next, check the piston assembly. The blue one is made by SHS. Note that the width and rack position may differ slightly depending on the manufacturer.

Well, it seems okay. Be aware that SHS piston racks may or may not be glued depending on the production lot. This one was glued.

I'm going to do a test assembly of the piston head. I'm installing DCI's side intake system, but the thrust bearing is difficult to install, so it's easier to use a screwdriver as a guide to insert the bearing.

We're temporarily assembling the piston and cylinder assembly to check for airtightness.

It's perfectly airtight.

Check each gear

Let's start with the bevel gear. The one on the right is the original, and the one on the left is from Super Shooter. The number of latches increases from 4 to 6, which is a nice improvement. The teeth that engage with the spur gear are also definitely better on the Super Shooter one.

Spur gear. This time, the one on the right is from Super Shooter and the one on the left is the genuine part. The precision of the gear cutting is definitely better on the Super Shooter one.

Finally, the sector gear. The one on the right is from Super Shooter and the one on the left is the genuine part. The key points here are to compare the position and shape of the cam and bearing that pull the tappets, and to check the timing of the cutoff on the back. You can't really tell without a test assembly, but I'll take a look anyway.

Now that we've finished checking the replacement parts, we'll do a test assembly.

Preliminary assembly of the gearbox

For now, I'll assemble the movable parts other than the springs.

Actually, at this point, the Laylax tappet plate was interfering with the microswitch and couldn't be used, so I switched back to the original. It could be made to work with some modification, but there didn't seem to be any benefit in going to that much trouble.

Here, we move the gear to check if the nozzle moves smoothly back and forth. After that, we check if the height of the tappet vanes and the height of the sector bearing are aligned.

Nozzle fully forward

Nozzle retracts to its final position

Once we've confirmed all of this, we can pretty much decide which parts to use. This kind of checking is tedious, but we do it thoroughly to reduce problems later on.

Next is machining the motor and sector gear.

Machining of motors and sector gears

The gear ratio we'll be using this time is 16:1, and according to the specifications, the motor should spin at around 37000 rpm, so we'll be cutting the sector gear. With a 16:1 gear ratio, I don't expect it to fire 25 rounds per second, so we'll cut two teeth from the sector gear.

I'm cutting two teeth on the pull side because I'm worried about semi-automatic overruns. Cutting the pull side will reduce responsiveness, but it's okay because I'll be able to achieve high responsiveness by changing the gear ratio and motor.

If the motor is a torque type, one plate for pulling and one plate for the end of engagement might be sufficient.

Then, apply the ink carefully to avoid mistakes.

Next, we prepare the motor for modification. PTS Masada motors are short type, but the motor I bought is a medium type, so I'll remove the pinion and cut the shaft. (I bought a medium-type Lonex A3 because it was half price. It's usually better to buy the short type to avoid the hassle.)

Either way, Lonex pinions tend to squeak a lot, so replacing them is almost always necessary. Laylax pinions generally work well with most models.

First, remove the pinion. I use the pinion remover from Eagle Model, as usual. The press-fit of the Ronex pinion is extremely tight, so I hook the extension bar of the tool onto the remover's handle and turn it slowly.

　

There are cheaper pinion removers available, but they seem like they might break easily, so I recommend the Eagle Force brand.

Eagle Model Pinion Remover
There are cheaper options available, but since rigidity is crucial for tools like this, I use this sturdy-looking one. It's only about 1000 yen more than the cheaper ones, so it's around 4000 yen, which I recommend.

Once the pinion is removed, compare its length to the original motor. It's roughly a 6mm cut.

Mark the motor and mask it to prevent metal shavings from getting inside.

Next, attach a diamond cutter to the rotary tool and cut the sector gear and motor all at once. The motor shaft is made of very hard steel, so it will take some time, but cut it without rushing.

• Diamond cutter, shank diameter 2.35mm
It's very useful for machining iron-based parts such as gears. A hard diamond is recommended if possible.

The processing is complete. After cutting with a cutter, I shaped it with a tungsten carbide bit and finally polished it with #1000 grit sandpaper.

Tungsten bit for rotary tool, shank diameter 2.35mm
Tungsten, the second hardest material after diamond, is recommended considering the price. It cuts very effectively.

Next, attach the Laylax pinion gear to the motor.

We will check the length against the original motor.

It's looking good. The end bell of the Ronex motor can be disassembled, so I took it apart and applied grease to the bearing located inside the end bell.

Just put it back together and you're done.

I've already exceeded 3000 characters, so I'll stop here for now.

To be continued in the next installment. Please stay tuned if possible.