A&K Masada SPR - DMR Theory Crafting

[Hudson]

From what I remember there were several different cuts of window in PDI barrels. Was one of the reason why they were a bit of a nightmare to R-Hop, together with the angles of certain cuts.

Maple Leaf MR bucking compared to a PDI 6.05 AEG barrel.

It's actually a better fit than I thought it would be.

I remember having issues trying to use an old Autobot bucking on the PDI VSR barrels.

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[MrTea]

Parts have been ordered and I've already got 90% of them. Annoyingly, the Wiitech hop parts (inc nozzle) are coming from Hong Kong so i'm going to be waiting for a couple weeks on those to arrive. The only changes I've made to the list are as follows;

• I've ordered some LY "J"-caged bearings which AK2M4 say have survived 300k+ cycles on M140 springs and are a third of the price of EZO bearings. The bearings are 3mm "tall", about 0.5mm taller than standard bearings which can cause clearance issues with selector plates which may need some sanding to allow these to fit. Hopefully I have no issues with them fitting and it'll help reduce some gearbox noise. I ordered the bushings just in case I still needed them.
  
• I couldn't get Guarder SP springs, out of stock from both places I ordered so I had to suck it up and live with XT springs for now.
  
• Inner Barrel; I couldn't get a Lambda SMART like Leo Greer suggested. I was planning on going for the Lambda Evo 6.08mm at 363mm long. This didn't give me an ideal ratio but wasn't too concerned as it was only slightly off until I discovered that Lambda Evo have a 6.12mm diameter at 363mm long meaning it was the perfect length for the 2.48:1 ratio and for £33, I don't think I could go wrong with this given it's only slightly more expensive than the cheapest offering.
  

I would have liked to start the build today but the lack of a nozzle means I'd have to take apart the gearbox again once it arrives so i'm having to sit on my hands for now.

 

[Lozart]

• I couldn't get Guarder SP springs, out of stock from both places I ordered so I had to suck it up and live with XT springs for now.
  

You'll be fine, they're very good springs!

Also (absolutely no disrespect to @Leo Greer) some of the parts that have been recommended by Leo are easier to get hold of in the US. Doesn't mean the parts you can get here/via HK aren't going to be just as decent. 

 

[MrTea]

You'll be fine, they're very good springs!

Also (absolutely no disrespect to @Leo Greer) some of the parts that have been recommended by Leo are easier to get hold of in the US. Doesn't mean the parts you can get here/via HK aren't going to be just as decent. 

I know, i've only used XT springs so far. I had read elsewhere (can't remember exactly where) that guarder SP springs produce less noise/twang somehow? Possibly the material they're made from? Was going to try it out and see what kind of a difference it made, if at all. I've seen someone suggesting putting heat shrink on parts of the spring to reduce the vibrations and noise which seeems unlikely and i'm not in a hurry to test that one

 

[Leo Greer]

@Lozart

Good point on parts availability. I try not to recommend anything I know is super hard to find, but I’m sure it happens…

@MrTea

Glad you’ve been able to find most of the items you need! I’m watching the thread waiting to hear what you’re able to get out of it.

 

[Lozart]

guarder SP springs produce less noise/twang somehow? 

Sounds like standard internet bollocks to me. Like polishing the mains plug on your hifi!

 

[MrTea]

Glad you’ve been able to find most of the items you need! I’m watching the thread waiting to hear what you’re able to get out of it.

Probably more questions and frustrations if experience is anything to go by

 

[Leo Greer]

Certain springs are quieter, in my experience, but Guarder are not especially so. They’re also not especially loud either. If you really want to make your spring quieter, you can just put some shrink wrap around a few of the coils.

 

[MrTea]

 If you really want to make your spring quieter, you can just put some shrink wrap around a few of the coils.

I did mention that one earlier but I only saw it in one place and no one seemed to confirm this one so I thought it was a myth!

 

[Leo Greer]

I did mention that one earlier but I only saw it in one place and no one seemed to confirm this one so I thought it was a myth!

It is indeed real, my good sir. I believe people have also used different kinds of rubberized sealants in thin layers, but I’d go shrink wrap for simplicity (you seal it with a heat gun or hair dryer).

 

[Lozart]

It is indeed real, my good sir. I believe people have also used different kinds of rubberized sealants in thin layers, but I’d go shrink wrap for simplicity (you seal it with a heat gun or hair dryer).

Surely that would affect the spring compression though?

 

[Adolf Hamster]

In general i've found the elimination of spring twang to be a nice side-benefit of using precocking, so that might be worth considering.

I did try the heat shrink once, but found it didnt help much and pretty quickly wore through making a mess in the process, although it may have been the breed of heat shrink i was using.

 

[MrTea]

In general i've found the elimination of spring twang to be a nice side-benefit of using precocking, so that might be worth considering.

Yup. I've got a Perun Hybrid ready to go. I was interested in testing, what I assumed to be, a useless throwaway comment in some corner of the internet.

 

[Leo Greer]

Surely that would affect the spring compression though?

Let me see if I can dig up some more info. As far as I’m aware there is no such effect.

I know people who do the mod in builds running 70 RPS+, but of course it depends on what you use, where you put it, how much, etc. Let me see if I can ask some the high RPS techs how it wears in.

 

[MrTea]

Well. Things didn't go as planned... I sat down today to start work on the DMR. I cleaned the gearbox shell and everything in it. Replaced the bushings/bearings with the nice new bearings from AK2M4 and reshimmed. The etched shims make it really easy to tell what you're using. The extra 0.5mm in bearing height didn't cause any issues with the selector plate so i'm happy about that. Compression set changed and is fantastic. Interestingly, the DMR version of the Masada has a quick change spring where I don't think the Carbine versions does. The spring guide I ordered is a non-quick change one so i'll sort that whenever, it's a 2 minute job to get to.

Fuck ambidextrous selectors. I got it working but it can fuck right off.

Test the mosfet to make sure it's seeing the different selector positions. Bingo. Pop the new motor in and gently bend the motor connections----SNAP. Ah for fuck sake. The little spade connector for the positive tab snapped rather than bending. Thankfully there's loads of spare wire for me to put a new one on tomorrow once i've paid halfords a visit.

 

[Colin Allen]

Well. Things didn't go as planned... I sat down today to start work on the DMR. I cleaned the gearbox shell and everything in it. Replaced the bushings/bearings with the nice new bearings from AK2M4 and reshimmed. The etched shims make it really easy to tell what you're using. The extra 0.5mm in bearing height didn't cause any issues with the selector plate so i'm happy about that. Compression set changed and is fantastic. Interestingly, the DMR version of the Masada has a quick change spring where I don't think the Carbine versions does. The spring guide I ordered is a non-quick change one so i'll sort that whenever, it's a 2 minute job to get to.

Fuck ambidextrous selectors. I got it working but it can fuck right off.

Test the mosfet to make sure it's seeing the different selector positions. Bingo. Pop the new motor in and gently bend the motor connections----SNAP. Ah for fuck sake. The little spade connector for the positive tab snapped rather than bending. Thankfully there's loads of spare wire for me to put a new one on tomorrow once i've paid halfords a visit.

The selectors on the A&K Masada are notoriously awful; neither of mine has a right side selector any more.

 

[MrTea]

The selectors on the A&K Masada are notoriously awful; neither of mine has a right side selector any more.

It's annoying that they're just grub screws into a soft metal that deforms extremely easily. It can't be that hard to make them from a stronger material and tap a thread?

 

[Colin Allen]

It's annoying that they're just grub screws into a soft metal that deforms extremely easily. It can't be that hard to make them from a stronger material and tap a thread?

Over many years, I have seen far more of them without the right side selector than with it.

Removing the right hand selector, along with the gear wheels and shaft, means that you do not have to remove the remaining selector to remove the gearbox.

 

[MrTea]

Over many years, I have seen far more of them without the right side selector than with it.

Removing the right hand selector, along with the gear wheels and shaft, means that you do not have to remove the remaining selector to remove the gearbox.

As much as i'd like to do that because I know i'm going to have to take it apart again at some point, my inner perfectionist refuses to do it and i'd rather spend an hour battling with it so it works rather than removing the functionality

 

[MrTea]

--- UPDATE ---

Halfords saves the day. Got a box of spade connectors and they fit the motor tab perfectly fine and there was plenty of wire left to clip the old one off and replace it with this new one. Banged the motor in and test fired. Gearbox is working nicely.

Now the hop unit. The wiitech hop unit is trash, despite looking very nice. The hop arm gets stuck in the body of the hop unit with full hop is applied. The hop adjustment piece doesn't actually fit on the hop unit and pops off at a whim. The tabs/wings on the hop unit which lock into the Masada outer barrel are too wide and even with a fair bit of force will not go into the outer barrel. I've had to take the metal hop arm and brass nub from the Wiitech hop unit and put it in the stock plastic hop unit for now just to get a functioning gun. I'll have to search around for the AirsoftPro version. The loading ramp and nozzle were fine, no problems with them and function fine with the stock hop unit.

I grabbed a bottle of 0.2g BBs and tested the FPS. I got a few wonky readings because I had no hop applied and was pointing the gun down allowing some BBs to escape but it's sitting between the 400fps-405fps area. My site limit is 420fps for DMRs so unless I can get a better airseal to grab those last few FPS, i'm okay with it sitting here power wise. A new/better hop unit (that actually fits) may improve the airseal to the point of hitting the site limit, hopefully, maybe. Will have to do some reliable testing once i've sourced another hop unit.

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Here's a nice pic of the bevel gear too, looks like it's had a hard life.

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