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Old 02-07-2020, 07:13 AM   #1
ninjagazz
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Rob Allen Tests Stainless Trigger Mechs

Hi Guys,

I recently came across this video made by Rob Allen where he was testing one of his mechs being fired over 200 times in a pneumatic device designed to simulate normal firing conditions. He used for this experiment a stainless trigger. His finding showed there was some wear at the contact points and some small stainless particles. The shot began firing with different trigger loads.

https://www.youtube.com/watch?v=92Mt...81059852582831

I found this surprising as i have a riffe euro that has shot well over 200 shots and still shoots beautifully, I also used a salvimar Hero extensively in the coral sea with 3 rubbers and before hand and found this mech shot with minimal trigger load and was very predictable. The Hero is a excellent gun.

I was surprised at his results and questioned his methods, ie SS grades/ polishing / heat treatment etc?

He said he had done the same testing on 3 other brands and found the same issues (not my brands).

This left me a wondering if others had heard of this before? I herd some people complain about the aimrite mechs getting stiff. Is this why people are using rollers in their triggers now? I have some neptonic mechs and wonder if they will become consumables.

Also given this, wouldn't the sear tooth wear? Especially when up against hardened Spring Steel?

Just wondering what peoples thoughts are.
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Old 02-07-2020, 07:39 AM   #2
popgun pete
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Re: Rob Allen Tests Stainless Trigger Mechs

The gun is repeatedly firing without moving and any debris is not getting out. In practice a speargun fires a shot and is moved around a lot by floating free as you take care of the fish, then you reload it and all that moving around and changing in orientation allows any particles to exit the cassette or sear box. If he had a water jet blowing through the mechanism then the test may have more closely resembled actual service conditions.
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Old 02-07-2020, 08:00 AM   #3
Diving Gecko
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Re: Rob Allen Tests Stainless Trigger Mechs

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Originally Posted by ninjagazz View Post
Hi Guys,

I recently came across this video made by Rob Allen where he was testing one of his mechs being fired over 200 times in a pneumatic device designed to simulate normal firing conditions. He used for this experiment a stainless trigger. His finding showed there was some wear at the contact points and some small stainless particles. The shot began firing with different trigger loads.

https://www.youtube.com/watch?v=92Mt...81059852582831

I found this surprising as i have a riffe euro that has shot well over 200 shots and still shoots beautifully, I also used a salvimar Hero extensively in the coral sea with 3 rubbers and before hand and found this mech shot with minimal trigger load and was very predictable. The Hero is a excellent gun.

I was surprised at his results and questioned his methods, ie SS grades/ polishing / heat treatment etc?

He said he had done the same testing on 3 other brands and found the same issues (not my brands).

This left me a wondering if others had heard of this before? I herd some people complain about the aimrite mechs getting stiff. Is this why people are using rollers in their triggers now? I have some neptonic mechs and wonder if they will become consumables.

Also given this, wouldn't the sear tooth wear? Especially when up against hardened Spring Steel?

Just wondering what peoples thoughts are.
In reg. to your comment on the RA video about if this was a real world issue, no brands would use SS triggers, you'd be surprised... A lot of products are not made to be as good as they can be and sometimes marketability drive design decisions. Also, for a few years I have seriously doubted how much these big brands actually test their products before they market them.
Full SS triggers look better for sure, but they may very well not always be.
I have personally pool tested a brand new gun from a European brand with a pretty long history that came with a full SS trigger (different brand than the one Majd has talked openly about) where it was almost impossible to get a shot off when the gun was rigged with two 14mm bands. Gun looked nice but shot absolutely horribly and the line release often didn't even open enough to let the line off...!

I guess it's been two years or so by now, but Majd has documented a galling issue in at least one very popular Euro gun brand's triggers. IIRC, his thinking is that it probably happens a lot more than many spearos realize and that they end up blaming themselves or other factors for poor accuracy. I think his findings were what spurred him onto a long pursuit of trying different metals, treatments and coatings and finally settling on double roller triggers as a way to help eliminate the problem.

As for your Salvimar, I am actually very happy to hear the Hero trigger works well, because they, too sent guns out not that long ago with full SS triggers that could be incredibly hard to pull and not be consistent - I think it was an earlier iteration/model than yours, maybe just the one before yours. I have that first hand from a friend who, before he knew of the issue, sold a few of these guns and it was talked about here, too a year or two back. I can't recall if it was a friction/galling issue and/or bad geometry but either way, it was a full SS trigger from a big brand which reportedly had issues.

On a related note, the latest Mares Cyrano (airgun) handle has a SS line release rubbing against a SS trigger. You would have thought there would hardly be any friction to speak of, but in my opinion, after having shot the gun for about a month, the design is an abomination. With just a little bit of tension on the line release from "normal" line wrapping, the force needed to break the trigger increases four fold. With a breakaway setup, that can sometimes pull a bit more on the shooting line, the trigger could get so hard to pull that I have lost fish because of it. Basically, zero consistency in between shots - and that's even after I have polished the parts to a shine. And that's not from visible galling, just from friction between two pieces of 316(?).
(As for hardening 316L I don't think it can be hardened by heat treatment, like e.g. 17-4ph).

I actually think it is very cool of RA to do a test like this and share his thinking and I find his responses to your comment about you not having any issues humble as well. And still, the close up pics of the galling are pretty telling. Majd saw very similar galling in his triggers just from testing in the pool. Some spearos have taken their "real world use" triggers apart and reported the same, and some have said they don't see any galling. Whether that speaks to particles washing out between shots or differences between batches or something else, I don't have the faintest idea about.
Having a half plastic, half steel trigger like e.g. RA, Pathos d'A1 or Abellan is a workaround to the galling issue but doesn't look good for the bling part of selling a gun.

So, that makes three brands/models I know of (not counting the airgun) that, in my eyes, have pretty much been proven to be at risk of developing issues. I don't doubt that RA has found three, either nor would I be surprised if at least a few of them are not the ones I have in mind.

Last edited by Diving Gecko; 02-07-2020 at 10:29 AM.
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Old 02-07-2020, 01:43 PM   #4
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Re: Rob Allen Tests Stainless Trigger Mechs

Diving Gecko, you have an engineering mind as does Pete. To me that test looked a little strange.. What was all that Jerky movement? Doesn't surprise me in the least that there were galling issues. ?? 304 Stainless Waterjet or Laser Cut Trigger? I couldn't tell I would hope it was waterjet, but could have been laser cut and then polished. Laser cutting would have considerably lessened hardness of the ?? 304 part as it will create a 'crumble' crust on the edges. I didn't listen closely to the entire video. Maybe he explained what the Sear Materials were?

Ofcourse using Metal/Metal is not the most ideal for friction. But Friction is not the only issue when it comes to the lifetime use of a Speargun.
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Old 02-07-2020, 04:08 PM   #5
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Re: Rob Allen Tests Stainless Trigger Mechs

One aspect that causes galling is too much pressure on the trigger retention step where it holds the tail of the sear lever. You can also find it where the sear lever tooth hangs onto the shaft tail notch. Galling is a product of high band loading, and in the case of the trigger step on a forward mechanism with the sear lever in front, when there is very little gearing in the sear lever itself. A classic example is the Voit Swimaster later JBL trigger mechanism because the pivot pins are set too close together and that cuts down the space available for a long sear lever tail. When that gun was equipped with three high modulus rubber bands the contact surfaces progressively chewed up, so the mechanism was strengthened by the addition of carbide inserts. That is basically the difference between the standard JBL gun and the XHD models which are the guns equipped with the carbide inserts.

If you engineer a trigger mechanism to have a long sear lever tail then the contact pressure goes down and that was the main advantage of the Undersee and the Riffe trigger mechanisms. Reverse trigger mechanisms can also have long sear lever tails, some mechanisms are better than others as the downside is the contact pressure is spread over too small an area, which was the problem with the Sea Hornet trigger mechanism with its thin levers in terms of their width. There was a thicker lever version for greater band loads, but it was discontinued as it was not required for most users’ requirements back in the day.

As for shooting line tension and line release levers bearing on the mechanism levers from the side the only guns that need a tightly strung line are open muzzle guns where the shooting line retains the shaft in the gun, there is no need for a very tight shooting line on a closed muzzle gun as if the gun is inverted the shaft cannot fall off the guide track. In the case of a pneumatic the line wraps can be relatively loose or just snugged up by not stretching the line bungee too much if the gun uses one.
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Old 02-07-2020, 06:41 PM   #6
Diving Gecko
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Rob Allen Tests Stainless Trigger Mechs

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Originally Posted by Behslayer View Post
Diving Gecko, you have an engineering mind as does Pete. To me that test looked a little strange.. What was all that Jerky movement? Doesn't surprise me in the least that there were galling issues. ?? 304 Stainless Waterjet or Laser Cut Trigger? I couldn't tell I would hope it was waterjet, but could have been laser cut and then polished. Laser cutting would have considerably lessened hardness of the ?? 304 part as it will create a 'crumble' crust on the edges. I didn't listen closely to the entire video. Maybe he explained what the Sear Materials were?



Ofcourse using Metal/Metal is not the most ideal for friction. But Friction is not the only issue when it comes to the lifetime use of a Speargun.


I like the idea of having an engineering mind, but Pete is one of the real engineers here. Thanks anyway:-)
I think the jerking you saw was just from the shot. The test bench uses an air cylinder to pull on the shaft with about 120kg of force (I think that’s what he said) and once the trigger releases, I guess the gun “jerks” back a little.

I wouldn’t be surprised if there are some great full metal triggers out there - and also it’s been mentioned before that going to reverse triggers makes it more challenging designing issue-free triggers.

It’s an interesting point about the laser cutting and crusting. Come to think about it, I think the trigger I mentioned seizing up in the pool was laser cut and did look a little ragged. So, perhaps that could be more of an example of a manufacturer going for bling instead of really bothering to quality test and solve issues. I’ll try to ask my friend if he polished any of these triggers and made them work.


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Old 02-07-2020, 07:24 PM   #7
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Re: Rob Allen Tests Stainless Trigger Mechs

Crusting is not the technical term.. HAZ Heat Affected Zone is the correct term. When a Sear piece is Laser Cut, there is a Heat Affected Zone along the edge which runs relatively deep. Even after the part is smoothed in a tumbler and polished there is still this area which is much more prone to "crumbling"

Water Jet Cutting avoids this, but still Water Jet Cutting of Sears is not perfect as it's not a very smooth Surface resulting. Even after Tumble and Polish.

This brings us to MIM. Metal Injection Moulding. What is nice about this process for sears is that you can design a 3D part. The Tolerances are extremely High. The finished Part is comparatively very smooth. Since you are Forging the part, you can choose your Material composition. And you are probably not going to choose 304 given other options..

In any case. It's cool that people do set up these Cycle Testers for parts. I remember seeing Tin Man's and his results of 1000 cycles on the Mech he developed. I've seen some very cool Mech Testers at the Aimrite Factory.
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Old 02-07-2020, 08:26 PM   #8
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Re: Rob Allen Tests Stainless Trigger Mechs

Good discussion,

120kilo load seems very excessive, surely a normal RA wouldn't experience there pressures?

I know freedivers and rabitech recently changed to SS triggers. The price of Freedivers is significantly less than that of RAs here in Australia (I reckon the RA distributors here are making good $$).

I was looking at the freedivers rollers (with bearings) earlier, as they can be bought for less than a RA.

No body has answered my question about the effect on the sear tooth? is this not normally a problem.

Diving Gecko I think the early "Salvimar Metal" were the guns with the trigger issues they use a different mech to the hero. I think the rollers were failing under heavy load.

I would appreciate to know of other brands that have had issues.
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Old 02-07-2020, 09:05 PM   #9
popgun pete
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Re: Rob Allen Tests Stainless Trigger Mechs

The tooth can get damaged, but not enough to stop the sear lever rotating and letting the shaft tail go. In forward trigger mechanisms the shaft tail sits in a short tunnel, so even if the shaft tail pops unevenly off the sear lever’s tooth it cannot jump around much. Not so in reverse trigger mechanisms that only have a short roof and no sides or floor to control the shaft tail. The exceptions are the Sea Hornet and Biller guns where the shaft tail is in a long cylindrical tunnel. When JBL added carbide inserts they were on the trigger retention step and the sear tooth, while others have used spring stainless heat treated sear levers to combat the tooth being damaged.

Pelaj had troubles with their dipping sear tooth trigger mechanisms, they eventually fixed it, but the reputational damage had been done and basically it blew them out of the water.
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Old 02-07-2020, 10:08 PM   #10
Diving Gecko
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Rob Allen Tests Stainless Trigger Mechs

It’s common to test pretty much anything mechanical at higher than normal operating forces. But I get your point that it is not a normal load for simulating shots. My feeling is that the galling would probably have showed up at lower forces - just from seeing or hearing about it in a few other cases.

The gun that seized for me and my friend in the pool was an EPS (formerly Epsealon). Two medium cut 14mm small ID bands on a gun which has a two band muzzle so nothing excessive. Maybe shit geometry, maybe badly laser cut and ragged. Maybe a combo. But nonetheless a full SS trigger that should never have been sold.

Yes, Majd runs his 14-15mm small ID bands a bit hot but so does a stock Pathos with 2x16mm bands and he has seen galling from that use (D2 handle).

The Salvimar Metal guns I heard about had stock setup and still had issues - not excessive loads and as has been pointed out elsewhere, Salvimar claimed that trigger would have a very gentle trigger pull up to 150kg of band pull.

Like I said, I’m sure some designs are fine (eg the new Salvimar Hero) but I don’t agree with your assessment that if there were problems, manufacturers would not use full SS triggers. Just a few too many examples as I see it of ill conceived designs being rushed to market.

Maybe I’m just being overly critical and you are being a nicer guy;-)


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Old 02-08-2020, 12:57 AM   #11
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Re: Rob Allen Tests Stainless Trigger Mechs

Salvimar Metal triggers were faulty … even with 2 bands the trigger pull was atrociously bad. This was caused by poor tolerance of the fitting parts. This was "fixed" in the Hero version by putting the sears slightly more apart … but that is not a good fix. The proper fix is to ream the sear holes to 4.2mm and use 4.16mm pins. This doesn't allow the sears to crush each other and things work as they should. This works well for both the old Metal and the new Hero versions.

Galling is a material science problem with SS and although HAZ doesn't help, it is not the reason for galling. Water Jet cutting and even MIM (like in the Sporasub ONE) does not prevent galling. Poor design geometry is also a big factor in poorly performing triggers, especially if you put in ridiculously high tolerances which screw up even the best geometries. Triggers should be a precision product with high very high tolerances for things to work well. Many things in the production of triggers just make it impossible to get the correct tolerances. Bending machines don't have the correct tolerances of right and left holes to make sure the sear pin (or axle) is absolutely horizontal. Also laser cutting is just not the correct way to cut sears as it has very poor tolerance (especially with new fiber lasers) and hole finish is very poor. The correct way to cut sears is with EDM (10x higher tolerance than laser). The sear hole and matching pin need absolute precision to work well and that is only possible by having the hole CNC reamed to the exact tolerance. The sear rotates pretty much like a car wheel on an axle … if the hole is too loose the rotation will not be optimal. There are many other areas in a trigger that need to be high tolerance for things to work really well. Unfortunately all this costs a lot of money as most triggers are not mass produced in a high enough quantity to warrant the extra cost. For my triggers I actually make my own version of the DR Ermessub Trigger for a while now for my own use and for my buddies … but good news is that everyone should be able to get the same without having to pay the ridiculous amount of money I was paying to make my custom triggers. I have one of the latest batch of new generation DR triggers and they have same tolerance as the ones I am using. All EDM cut sears … CNC reamed holes for sears … perfect pin to hole tolerance … perfect rotation effort …. perfectly parallel holes in box so pins are absolutely horizontal .. just good tolerances everywhere. The old DR triggers were pretty good but a lot of them needed work to get them to work perfect. These new generation triggers are a huge jump forward and I think they will really change things as spearos will simply not accept crappy triggers anymore.
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Old 02-08-2020, 01:36 AM   #12
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Re: Rob Allen Tests Stainless Trigger Mechs

The levers in the Scubapro “Panther” are very accurately made as they are sintered stainless steel formed in a die which includes all the holes for pivots and spring locations as well as any narrowing tapers/cut-aways near the latter to provide room for the end hooks. I expect that these metal forming dies were not cheap to make, but then neither was the foam polypropylene gun whose transfer molding dies cost the price of a luxury European car. I don’t know how small the sintered levers can be, but it is something that would need to be fully sorted out before you committed to making the dies. For lubrication the metal is impregnated with molybdenum disulphide grease.

The edges on the levers are perfectly square to the lever faces, there are no tapers or bevels as you have on stamped levers.

Grease lubrication can help in trigger mechanisms, the big problem is sand sticks in the grease and then you have problems as you have a grinding paste in your gun as well as jamming potential as quartz is hard stuff, second only to diamond.

A problem with the "Panther" was it continued the deep Scubapro handle layout that it inherited from the previous tracked alloy barrel tube guns and before that the long trigger guns designed by Wally Potts. With a leveraged two-piece trigger mechanism it did not really need such a long trigger and deep mechanism except for the need to retain its distinctive looks.

Last edited by popgun pete; 02-08-2020 at 01:50 AM. Reason: extra comment
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Old 02-08-2020, 01:42 AM   #13
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Re: Rob Allen Tests Stainless Trigger Mechs

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The levers in the Scubapro “Panther” are very accurately made as they are sintered stainless steel formed in a die which includes all the holes for pivots and spring locations as well as any narrowing tapers near the latter to provide room for the end hooks. I expect that these metal forming dies were not cheap to make, but then neither was the foam polypropylene gun whose transfer molding dies cost the price of a luxury European car. I don’t know how small the sintered levers can be, but it is something that would need to be fully sorted out before you committed to making the dies. For lubrication the metal is impregnated with molybdenum disulphide grease.

Grease lubrication can help in trigger mechanisms, the big problem is sand sticks in the grease and then you have problems as you have a grinding paste in your gun as well as jamming potential as quartz is hard stuff, second only to diamond.

This trigger is using levers or at least is forces are leveraged... which dramatically reduces stresses on the sear surfaces. Only problem is this type of trigger doesn't allow for a highly elevated handle and of course it does not maximize band stretch. But I would much rather choose this than a poorly working reverse trigger that galls. And yes of course grease is not a good idea for underwater spearfishing use as it would require continuous maintenance of the grease. C4 also uses some type of grease on their mechs ... which I don't like at all.
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Old 02-08-2020, 02:03 AM   #14
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Re: Rob Allen Tests Stainless Trigger Mechs

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This trigger is using levers or at least is forces are leveraged... which dramatically reduces stresses on the sear surfaces. Only problem is this type of trigger doesn't allow for a highly elevated handle and of course it does not maximize band stretch. But I would much rather choose this than a poorly working reverse trigger that galls. And yes of course grease is not a good idea for underwater spearfishing use as it would require continuous maintenance of the grease. C4 also uses some type of grease on their mechs ... which I don't like at all.
The same technology could be used in a completely different design, you don't have to grease these levers as they are always slippery under load, yet sand does not stick to them. As far as I know no one else has pursued this technology since. Scubapro charged more for their gear than anyone else, so they put state of the art stuff into their guns, for example their take on the Mares "Sten" had not one brass part in it, unlike the original, and all the plastic parts were thicker and reinforced, but you paid a lot more for them.
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Old 02-08-2020, 05:13 AM   #15
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Re: Rob Allen Tests Stainless Trigger Mechs

Interesting discussion
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