A&K Masada SPR - DMR Theory Crafting

[Lozart]

47 minutes ago, MrTea said:

guarder SP springs produce less noise/twang somehow? 

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

[MrTea]

28 minutes ago, Leo Greer said:

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]

1 hour ago, Leo Greer said:

 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!

Edited August 28, 2023 by MrTea

[Leo Greer]

17 hours ago, MrTea said:

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]

20 minutes ago, Leo Greer said:

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]

3 hours ago, Adolf Hamster said:

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]

4 hours ago, Lozart said:

 

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.

Edited September 9, 2023 by MrTea

[Colin Allen]

1 hour ago, MrTea said:

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]

2 hours ago, Colin Allen said:

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]

32 minutes ago, MrTea said:

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]

47 minutes ago, Colin Allen said:

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.



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

 

Edited September 10, 2023 by MrTea

[RostokMcSpoons]

@MrTea, I nearly went to Halfords too, as I need a spade connector to resurrect my Classic Army M16. I realised I didn't know if they had the right ones - what size do I need to ask for?

[MrTea]

4 minutes ago, RostokMcSpoons said:

@MrTea, I nearly went to Halfords too, as I need a spade connector to resurrect my Classic Army M16. I realised I didn't know if they had the right ones - what size do I need to ask for?

 

I used these.

These should also work.

 

I will say, the actual spade connector which goes onto the motor tab is crimped a touch too tight and I had to use a small flathead to pry them open a bit more so they went onto the motor tab without forcing it on and potentially damaging the motor. If you don't have one already, i'd suggest getting a crimping tool.

Edited September 10, 2023 by MrTea

[Haru]

i needed spade connectors too I just got mine from ak2m4

[MrTea]

New hop unit from AirsoftPro ordered. Hopefully this one actually works. Prolly going to take 2 weeks to arrive so the DMR won't be viable for my next outdoors session.

[MrTea]

The hop unit from AirsoftPro arrived and was installed. Went in like a treat with none of the issues from the Wiitech one. What I didn't do is change the nozzle to the AirsoftPro one because I was short on time and just wanted to see if the hop unit fit.

 

I decided to do some testing to get some initial FPS readings and it's not good. The single highest FPS reading I got was 274.4fps on 0.36g (1.26joule) which is 368.3fps on 0.2g. In addition to the low FPS, it's also massively inconsistent with a ~50fps difference between the highest and lowest FPS reading. I'll have to go back into the gearbox and use the AirsoftPro loading ramp and nozzle to see if it makes a difference in the FPS in testing. The airseal from the compressions parts (with the nozzle on too) was great when I tested during installation so I know that's unlikely to be the issue. For reference; the limit on 0.36g is 313fps (420fps on 0.2g) or 1.64 joules. As long as i'm over 300fps on 0.36g with a max variance of 3-5fps i'll be happy.

 

Fixing the inconsistency is key in my mind. If the FPS was consistent but low, I wouldn't mind. Boosting FPS is easy through spring strength, it's the inconsistency that's got me wondering.

 

In other news; the spring guide for the A&K Masada SPR is a non-standard size. I ordered a QD bearing spring guide and that's also too big. I measured it with calipers and cannot find any spring guide with a similar size. I've also 'shimmed' the inner barrel to the outer and that thing is rock solid now, zero movement at all.
 

Edited October 4, 2023 by MrTea

[MrTea]

Back again and i'm moving in the right direction, FINALLY. I sat down this morning after mulling over my options and remembering someone having a somewhat similar issue with their AEG being massively inconsistent and it turned out their bucking was causing the issue. I stripped the rifle and disassembled the hop unit.

Here's what the hop unit looks like with the ML MR Hop rubber installed.



 

I took the hop unit apart and compared it to the stock hop rubber as seen below. Apologies for the poor focus.

 

 

Interestingly the stock hop rubber is a few millimeters longer than the ML MR Hop rubber. I put the stock hop rubber into the hop unit and as you can see below, despite being longer, the feed lips(?) don't protrude into the hop unit as far.

 

 

I PTFE taped the hop rubber and hop unit in keeping with my first attempt at assembling the hop unit just in case the PTFE was somehow causing my issues. I rebuilt the gun and went to test it on 0.2g BBs and then 0.36g BBs. Results are below;

 

 

Now i'm getting somewhere! Interestingly the power has gone UP from before and, thankfully, it's consistent! I'm impressed that on 0.36g BBs i'm getting 3.2fps difference across 20 shots, that's probably my best yet of any of the AEGs i've worked on.

 

My issue now is; does this gun require a different length or type bucking to work correctly or is possibly just the ML MR Hop rubber causing issues? As for the power it's producing, i'm aware it's well short of the 420fps on 0.2g BB (313fps on 0.36g)/1.64Joule limit i'm looking for and I do have an M150 spring kicking around in my spares box somewhere. I would have slapped it into the gearbox but my screwdriver fell to bits on me this morning and i'll have to wait for another to arrive on Sunday which is a bit annoying but still... progress!

@Leo Greer I'd like to pick your brain over the hop rubber issue. Have you ever ran into anything like this before? Should I just try trimming the feed lips by a millimeter or two so it matches the stock bucking length when installed?

Edited October 13, 2023 by MrTea

[Lozart]

Maple Leaf rubbers quite often have rather long feed lips. You could try GENTLY sanding it down to the point that it feeds OK. Can be a bit of a gamble if you take too much off and knacker your airseal.

 

Alternatively you could flat hop or R-Hop with a prommy rubber.

[Adolf Hamster]

13 minutes ago, Lozart said:

Can be a bit of a gamble if you take too much off and knacker your airseal

 

There's also ensuring that the lips remain square and dont have blemishes etc that could cause an air leak.

 

much like trimming a nozzle its often easier to just buy a different part.

 

56 minutes ago, MrTea said:

Interestingly the stock hop rubber is a few millimeters longer than the ML MR Hop rubber

 

It's relatively common to see some variation in what for want of a better term i'm going to call skirt length on a hop rubber.

 

Too long generally is an issue if you can't get the c clip to stay put, within reason shorter is ok.

 

59 minutes ago, MrTea said:

My issue now is; does this gun require a different length or type bucking to work correctly or is possibly just the ML MR Hop rubber causing issues?

 

Some guns just dont like some buckings, typically i like pdi w-hold when a gun doesnt want to play ball with maple leaf, although certainly at 1j the w hold can struggle to lift north of ~.32's, you might be ok at dmr power though.

 

 

[MrTea]

@Lozart @Adolf Hamster

Thanks for the insight, i've never ran into this issue so it's a new one for me and all the previous ML stuff i've used has just worked a treat. I've got two ML MR Hop 70 degree buckings so I might try "adjusting" the lips of the bucking to see if I can improve feeding.

 

As for the PDI W-hold, the stock bucking looks pretty similar in it's contact patch/mound shape.

 

I'm at a bit of a loss as for what other buckings/nubs to use in a flat-hop setup (if I screw up fixing my current buckings). I know Prommy/Laylax sell a hard (red) flat hop bucking and the pack of two nubs but i've seen some forums posts elsewhere saying that Prommy purple is more than enough for 400-450fps with a hard flat hop nub.

Edited October 14, 2023 by MrTea

[Leo Greer]

On the ML issue, Lozart and Adolph pegged it—you can try sanding the lips, but ultimately it’s a spec issue. ML rubbers are designed to fit Taiwanese units like Maxx, G&G, etc. I have no clue where AirsoftPro falls on the lineup of Tawain/China/HK, but they all have different specs, courtesy of the wonderful airsoft industry.

 

I would personally suggest either flathop ping the stock rubber as a free try, or buying a flathop rubber. I don’t have experience with the unit you’re using, so I’m not sure what exactly will fit the best, but you can flathop pretty much any rubber.

 

The PDI W-Hold is usually contained with units that don’t like ML, and so are the Modify Flathop rubbers. Prommy should fit as well (I’d recommend purple), but they tend to be kinda expensive. And, of course, you can always just buy stock rubbers that are made from half-decent material like Guarder, Arcturus, G&G (similar to ML but may fit better), Krytac Blue and Orange, etc. Flathop really depends on the rubber and the nub, so the current contact patch shape doesn’t matter.

 

For a nub, I usually just use a piece of 8mm tubing cut into a rectangular patch, glued to the hop arm. This creates a concave contact patch and ultimately a similar effect to an MR. Hop that works with any rubber and barrel. You can adjust the height by either sanding it or adding layers of tape. Or you can simply cut your own nub out of hard plastic using small files. It can be flat or concave, either works. Then attach it to your hop arm (maybe sand the hop arm flat), with superglue.

Edited October 15, 2023 by Leo Greer