Renovating and Modifying a Mares Mirage

[Diving Gecko]

Not completely done yet, still some smaller "projects" in relation to this gun, but this is where we are now. It even seems to hold air, haha. (This handle is not the one with the busted trigger bushing thread. I have a custom-made UBL 1.4mm trigger assembly in this one).

(With my feet for scale)

It's a bit tricky finding out how I should name the gun in terms of length as the Mirage naming convention was a bit all over the place and models end up "longer" than if using the Sten naming rules (I don't know if the latter has changed over the years).

Come to think about it, my tank on this gun is exactly 45cm longer than the tank of the Mirage 80/84 model, so depending on whether I go with the new or old naming style for the Mirages, my gun is a GeckoMirage 125 or GeckoMirage 129.

[Edit] Got curious about the naming conventions and by comparing the barrel lengths of guns from different brands vs. their model designations, I figured out that this gun would be:

• 122.5 cm by Sten standards or;
  
• 120.5cm if it had been an Asso and finally;
  
• 114.5cm had it been a PredaThor

(I see a thread about the different brands' naming conventions coming up sometime soon... haha).

The gun weighs - excluding spear, rigging and reel - 1290g.
An app. 125cm, 7mm spear will weigh about 370g.
Total, without reel and rigging, is about 1660g and I think it will be very close to neutral in salt water.

If I drill a hole in the handle for the float line and rig it the gun could hunt now, but I still have some other mods that I would love to do:

• Cut spear down as much as possible. I like as little overhang as possible and could loose app. 10-12cm, which will help with the balance, too.
• Fill Vuoto nose cone with resin + chopped fiber and then drill it out to fit the Tomba slider. There is too much wiggle room as it is and I want the slider perfectly centered so it holds the shaft centered. This would hopefully also prevent the edge of the tail end of the shaft from hitting the shock absorber as it passes it - as it does now.
• Possibly build some small wings to give the gun a few hundred grams of additional buoyancy as I would like to see how it shoots with 7.5mm and 8mm spears. But with those, the gun would sink. It is barely neutral now.
• Make a new trigger in CF. Even though I cut down the original one substantially, it is still a bit too much of a reach.
  
• I had ordered some fluorescent optic fibers for sights but they never turned up, so not sure I can make those in time for the next trip as I will need to order again.
• I will probably need to cover parts of the handle in Sikaflex or 3M4200 for better grip. It is kinda slippery now.
• I have an idea for a line release interacting with the trigger itself through the hole where the safety used to be. But not sure if I have time for it. If I don't get around to it, I will just use the magnetic Pelengas line release which screws into the pump inlet valve.
• I am also working on a new CamWing to hold a GoPro or similar cam without loosing buoyancy (the CamWing has plenty of volume to "carry" the cam).

 

[Diving Gecko]

Another update as we are nearing a working gun.
Yesterday, I began making a foam float for the tank which will help the gun carry a thicker spear.

It is still way too big here, but the whole idea was to have it over-sized, place it just in front of the handle and balance the gun horizontally with lead in the handle. This would serve a few purposes. Besides increasing the buoyancy, the gun would track better than with a more forward placed float and the increase in mass would help handle the higher recoil from the thicker spears which should benefit accuracy.
But I figured I should check the real buoyancy or, rather, lack thereof to better help me decide how big the float needed to be.

After a trip to the bathroom, to perform a test in the bathtub, I was surprised: The Mirage 125 will actually float loaded with a 7mm spear!
I am really thrilled about this. Furthermore, my calculations show that it will be neutral with a 7.5mm spear and less than 60gram heavy with an 8mm spear. (This is for single flopper shafts, so slip-tip setups should weigh a tad more, but nothing too bad, I reckon).
This is great news and mean, I don't have to make a float after all.

My bathtub was too short to do the float test with a spear (the one I have is still 10-12cm too long), so I wrapped some small adjustment weights around the tank until it was neutral in the fresh bathing water;-).
My numbers mentioned above are adjusted for the added buoyancy from attaching the ballast to the outside of the tank as well as for saltwater with a density of 1.025 g/ml.

I am waiting for some more resin and carbon fiber sleeves for my second handle for the smaller Mirage as well as some new spears for this longer one. As mentioned, my whole idea is to simplify my travel setup to two Mirages and nothing else. And I want to mess around with different spear thicknesses, too.

My shorter Mirage is rigged with front-tied shafts but I think I will actually buy some slider shafts and finally do a few tests to see what is the most efficient/precise.
The longer one here, will use slider shafts exclusively - Jegwan and I was a bit worried that the pre-loading barrel would cause issues with the metal washer perhaps scratching or even jamming the spear, but the washer sits nicely perpendicular to the shaft just held in place by the line rest on the nose cone. That was a relief.

 

[Diving Gecko]

Just a few pics from last trip in the Philippines.
I was there to shoot some video, but squeezed in some pretty unsuccesful hunting. Not that the gun is to blame.
Was good to get it in the water though.

On the top: Hunter 90 with CF outer tank, Evo-Air vac muzzle, LG reel and custom handle (polymorph). Underneath it: Custom-lengthened Mirage 125 with CF outer tank, Vuoto muzzle, LG reel, Pelengas line release, CF camera wing and custom CF handle:

I made a quick and dirty textured surface on the handle by mixing beach sand with some white epoxy paint. Works a treat:

A Salvimar slip-tip on a custom made 7.5mm 17-4ph hardened shaft. I think I will make a new shaft for this setup with welded-on small tube for the slip tip line as I really don't like this huge slide ring:

The Pelengas magnetic line release. I had to glue a new magnet in as the old one rusted away in no time after a previous trip:

 

[Diving Gecko]

I am already thinking 0n how to improve this gun.
The biggest issue with the Mirages is that they can bust normal parts like pistons and shock absorbers that are not made to deal with the 30-40bar these guns can run.
Especially, the more modern, optimized parts like the ones from STC or the Vuoto from Salvimar. I have busted an STC piston and shock absorber and also the shock absorber in the Vuoto.

So, now I will try this kit from UBL (Underwater Ballistics Lab), which is actually just a very nerdy and fun Ukranian living in Cyprus called Dima.

A mix of stainless steel and titanium and as you can see a near clone of a Vuoto. Except, Dima has been making these for +10 years, so now figure out who cloned who...

I like the idea of the smaller tail end - it results in a small hole in the piston, leaving more material at the front of the piston. This should, hopefully, make it more sturdy. Also, the front is beveled and matches the shock absorber - again, the bigger contact area will hopefully help spread the loads of impact better.
We will see...

In another thread, Tomi mentioned that he did not really like the smaller tail ends as he did not believe they support the spear as much as a traditional piston and tail end and thus this newer setup would be more prone to the shaft bending. I have to disagree. I don't really see any difference and do not believe at all that the traditional setup offer an advantage in that regard. Actually, after having played around with the bits, I'd say that this setup might even be firmer in the transverse direction. But as I said, I don't buy the argument in the first place;-)

 

[tromic]

Very interesting toys, and nice clear images!

 

[tromic]

...
In another thread, Tomi mentioned that he did not really like the smaller tail ends as he did not believe they support the spear as much as a traditional piston and tail end and thus this newer setup would be more prone to the shaft bending. I have to disagree. I don't really see any difference and do not believe at all that the traditional setup offer an advantage in that regard. Actually, after having played around with the bits, I'd say that this setup might even be firmer in the transverse direction. But as I said, I don't buy the argument in the first place;-)

Maybe the piston is actually what is better supported by the - shaft. But that depends on the design of the piston. Piston with only one o-ring is better supported when firmly connected with the conical shaft tail end...?

 

[popgun pete]

On a high energy pneumatic gun I would use metal pistons and shock absorber anvils, which is what the original "Mirage" was equipped with in the first place (both cadmium-plated steel originally). A titanium piston with a stainless steel tail could be matched with a titanium anvil, in fact your contact in the Ukraine should be able to make a set for you. Plastic is just not up to the job, especially with a vacuum barrel muzzle not providing any braking on the piston during its flight down the barrel.

A rotating head could be incorporated into the new piston in order to allow spears to be twisted in the cocked gun without the piston tail climbing up off the sear tooth, however it would depend on the piston body length not becoming longer than necessary if a swivel joint was engineered into the design. Alternatively just use the barrel vacuum to hold the spear in the gun and eliminate the frictional coupling currently used.

Here is another extended (130 cm) "Mirage" on the LG "Revolution" forum referenced in that gun's thread here.

 

[Diving Gecko]

The titanium piston might not be a bad idea. It won't mushroom?

I'll see how this one will hold up for now, though. I'll also ask what he uses in his hydropneumatic tuna gun. That said, since I changed to a stock Mares Sten piston I haven't had any issues. But also haven't shot at more than 33bar yet. I broke the STC at less than 28bar if I recall correctly.


Sent from my iPhone using Tapatalk

 

[popgun pete]

The titanium piston might not be a bad idea. It won't mushroom?

I'll see how this one will hold up for now, though. I'll also ask what he uses in his hydropneumatic tuna gun. That said, since I changed to a stock Mares Sten piston I haven't had any issues. But also haven't shot at more than 33bar yet. I broke the STC at less than 28bar if I recall correctly.


Sent from my iPhone using Tapatalk

Not if the nose of the piston is matched to the anvil, same as was done with the earlier steel pistons and anvils which were not made of anything special. They tended to hammer into each other over time and survived high pressure shooting in my "Sten", albeit with a standard wet barrel.

 

[Diving Gecko]

[...]
Here is another extended (130 cm) "Mirage" on the LG "Revolution" forum referenced in that gun's thread here.
View attachment 42263

Yeah, I have come across 1-2 modified Mirages like these.
I think his is longer than mine. Maybe he was lucky to get his hands on an old Mares 130 Super Sten inner barrel?
My shooting barrel is from an Asso, but I had to cut off the first 5cm or so and cut a new Mares thread. That, and the fact that it lined up with a 100cm outer CF tank that I had lying around decided my total length.

If I wanted to go even longer with an off the shelf inner barrel, I could get a Salvi Vuoto barrel about 15cm longer than what I have now. That way I could make a 135ish gun. I would need to pay a CF tube manufacturer a bit more to make a longer than 1m tube but it would still be affordable. But honestly, I wont go that long with a normal 40mm outer tank. Even at 120cm, I feel like I can't track the gun fast enough.
So, only if I get around to making a custom tapered CF tube will I go for a longer Mirage. The pre-loading barrel doesn't need to run the whole length of the gun. It could just be half length making it possible to taper the front end substantially - perhaps all the way down to about 24mm or less in height. Obviously, more pre pumps would be needed but that would be OK.

Also, I am really following the performance of the better banded guns and the new breed of small ID 14mm bands. While I still think air has an advantage at smaller size guns, I am not yet sure we can compete when guns get longer, say with shafts longer than 120-13ocm'ish.

I have seen some very impressive tests on e.g. Pathos and Abellan guns lately done by someone who doesn't just shoot for accuracy. He always pairs it with a penetration test, too which most testers never do. And it is actually easy enough to make most guns shoot accurately if you don't push the power at all. The trick is to get the most power without losing accuracy and only a combined penetration and accuracy test can show if you manage that.

 

[Diving Gecko]

Not if the nose of the piston is matched to the anvil, same as was done with the earlier steel pistons and anvils which were not made of anything special. They tended to hammer into each other over time and survived high pressure shooting in my "Sten", albeit with a standard wet barrel.

Gotcha, I will talk it over with Dima. I am honestly more worried about the o-rings busting but only one way to find out.

 

[Diving Gecko]

OK, so just a few pics from recent trip to the Philippines - I ended up being there two and a half weeks but only had half a day in the water. I brought the upgraded Custom Mirage 125, took it on the boat but ended up bringing my Hunter 90 in the water. So, in the end, I didn't even shoot the Mirage once;-(
I even brought styrofoam targets for precision and penetration tests but turned out the viz in the pool was, literally, less then two meters...

I will go back in November and do some real fishing then. I left the foam targets there, too so if I can find calm ocean water, I can try to do some testing.

For now, some quick pics (Mirage 125 and Hunter 90). The handle on the Hunter is just a quick Polymorph one. I do have the mold done for a nicer carbon. The handle on the Mirage had a coat of white epoxy paint with beach sand to improve the grip:

And a shot of the Vuoto muzzle just before I replaced it with the one from UBL (Dima):

 

[Diving Gecko]

Oh, I did finally shoot an OK fish in that country (though not on the Mirage)...
A crocodile needlefish with beautiful green-blue bones. We BBQed some of it plus its big liver, made a soup plus a local raw fish salad called kinilaw (it's basically a ceviche):

I later read that the needlefish has actually killed fishermen as they are known to have jumped out of the water when stressed or attracted to lights on night-fishing boats. A 4kg needlefish turns into a dangerous javelin and its long sharp beak have, supposedly, impaled a few fishermen...

This one behaved very nicely - the shot broke it's spine a few inches behind the gill plate, so no javelin behavior

The meat has a slight green tinge to it, too but is nice and firm and tastes great. My local friends was very, very happy with it.

 

[tromic]

Very nice, all!
Have you tried UBL kit with the new titanium slider?

 

[Diving Gecko]

Very nice, all!
Have you tried UBL kit with the new titanium slider?

So far, only in my dreams...
I ran out of time on the latest trip as it was more a work trip than anything else. So, when I ended up only having half a day to spearfish, I jumped in the water with the gun I knew best - the Hunter 90 - which has a freeshaft setup and an Evo-Air muzzle.
The Mirage with the UBL kit will, hopefully, see some fish in November.

 

[Diving Gecko]

Just a teaser, but another Mirage handle hits the chopping board;-)
I'll take this one even further, I lost my respect for the unsullied Mirage on the last one;-)

The reason I cut of the trigger guard is two-fold. I want to raise my grip as high up as possible on this next handle and the guard was in the way. Also, this handle is the one that has a busted thread for the trigger pin bushing and to have a go at repairing it, I need much better access to the trigger area.

Next pic isn't too easy to "read" but I bought a very, very cheapo milling table for my likewise cheapo bench drill and this was the very first test cut:

Yes, of course it chatters but it'll be totally fine for the soft plastic of this old handle and I need milling capacity for especially one big mod to this handle. Stay tuned, this handle will see quite the make-over

 

[Diving Gecko]

There are a range of mods I want to do to this handle. Let me list them, before going more into details:

1. Custom Grip - as high as possible to reduce any tendency to flip the muzzle
2. An Active Line Release (see more below)
3. Increase Airflow
   
4. Bigger Rear Reservoir (for a better low power shot)
5. Bigger Transfer Port in Bulkhead (not sure I will do this one)

1). Custom Grip
This was my main modification on my last handle as the previous pages of this thread shows. The last grip was all about helping my instinctive aiming and this one will be very much like the last one, but I can't use the same mold. I will make the new grip with a more pronounced thumb rest and really work on getting the line of recoil in line with my arm (which was less of a concern the first time around, but nonetheless it did happen as a byproduct). Also, I will raise the grip on this handle as much as I can.
I definitely took a page out of Majd's (SpearQ8) book on recoil control here.

2). Active Line Release
This is what I teased about in the post above and the reason I got the little milling bed. It is hard to explain, but basically I am stealing the line release from a Salvimar Predathor and will incorporate it in the Mirage handle.
I would need to fill up some voids on the inside of the handle with epoxy before milling out a slot for the line release (see video). Also, a new trigger would be needed. I might even have to lower the holding pin for the trigger a tad, so that the line release sits on the axis of the trigger and doesn't exert a force on the trigger that could make the gun shoot accidentally.
I explained some of it in this little video:


3). Increasing Airflow
In regards to increasing the airflow in the handle there are a few ways to skin that animal. I am thinking of using one of the circular "empty" channels in the handle. They are open at the front end facing the bulkhead and I could open one towards the rear end and drill a hole in the shooting barrel, too. Another way, which was presented by someone else here, is to mill a channel on the top of side of the outside of the shooting barrel. I don't have machinery for that, though.

4). Bigger Rear Reservoir
I was never really impressed with the throttled low power shot of the Mirage (not talking about the V1 version here). I don't feel there is any real difference between position 2 (low power) and position 3 (full power). And position 1 (loading) is to meek to use as a lower power shot. (This is from feel, I haven't tested it).
As I have mentioned elsewhere, one way to go about this is to increase the volume of the airspace behind the bulkhead by inserting a spacer tube between the bulkhead and handle. The more I look at these parts, the easier it actually looks to do this. I just have to think a bit about how much bigger to make it. Once done, position 1 (loading) would also become the low power position and position 2 would not be used. Position 3 would still be the full power shot.

5). Bigger Transfer Port in Bulkhead
Finally, though tolerances are tight in that area - as in not much material on the sides - it is actually possible to enlarge the bore of the air transfer hole in the power regulator bulkhead. It is 6mm now. I can get to 7.5-8mm but it is a bit risky and not sure it is worth it. If any of you knows some formulas for the throttling of air then perhaps it would be interesting to look into that.

 

[Diving Gecko]

I have resumed my epoxy fun and games. Meaning I have had fun filling the handle with DIY 'fiber reinforced plastic' in preparation for attempting to mill out a slot for an active line release.
Now, as I wait for a few bits and bobs so I can fix the handle properly on the wobbly milling bed, I set out to do something futile...

I thought, why not really challenge this USD 18 milling bed for my USD 58 bench drill and try to mill the aluminum shooting barrel for the Mirage...?
As we have talked about a few times in various threads, the Mirage could possibly be a bit restricted in terms of airflow (I actually don't know if it is). So I followed Danilo's idea and set out to try to mill out a channel on top of the shooting barrel.

And... it worked!

First, a few pics of the setup.
Cheapo bench drill + cheapo "milling bed":

As a fixture for the barrel, I used these 'guide rail brackets' which I bought a while back thinking I could use them to hold oleo barrels during servicing of my guns. They came in handy now, though I had to drill them out to ø18mm first:

And here is the result. I took off 1.5mm leaving the barrel thickness at the very top of the barrel at 1mm. If there was an airflow restriction in the Mirage, this should help alleviate it. Next level up would be to open the bigger hole that is just visible on the lower left (right hand side of the handle).

 

[Diving Gecko]

Small update; we're getting there, it works: an active line release on a Mirage handle. Not as pretty as I hoped for (though the pix look worse than real life). Next up, I'll make a trigger and a trigger guard. Then on to the grip itself.

 

[Diving Gecko]

Forged in Mordor
That's really what sprung to mind when I saw how the putty grip I just did came out.
But first, a pic of how much I actually cut the original handle down this time. I remember being worried on the last handle when removing material but not so much any longer...;-). Truth be told, the top of the handle is very sturdy, the bottom not so much.

But back to Mordor...
I think the mix of epoxy, micro-spheres and chopped carbon fiber achieved exactly what I hoped - that it would be lightweight and strong. It is curing now, and I will post cure it at higher temps, but the putty felt very light when I mixed it up. I didn't have enough left to make a sample for density measurements, though.
In the beginning it was a little too malleable and wet and wouldn't really stay in place, but as the epoxy curing kicked in a little, it got easier to work with. Because there was so little of the original handle left there was very little support for the putty, so that didn't help eoither. But in the end it worked out fine. I made it a little small as I wanted to have a "second filling" and later on, cover it with carbon fiber. But actually, I may not need the carbon fiber after all.

I took the opportunity to trim it with a Stanley knife a bit before it sets rock hard.
But here are a few close-ups and perhaps, you can see how I got to think of Mordor's furnaces;-)

All the strands you see are carbon fiber and this is why I expect it to be very strong for what is basically a glorified putty;-)
(Actually, I can't help thinking I could probably make handles in this material if I make a nice mold... But that is definitely a whole other project).