My Swiss Arms Story: UPDATE Post#162, My Theory on the Extraction Issues

Looking at the photo's - I am interested in anyones take on what causes the casing to flip 180 degrees & lodge perfectly in line with the bolt -

As the carrier moves back through the cycle, the casing (gripped in the boltface) is brought up against the ejector (machined in the receiver) - this flips it at the same time as it flings it sideways.

So how does it "flip" without getting "flung"? (hope you understand what I'm getting at - not sure how else to explain it)

-too fast? Bolt cycles so fast it catches the casing in mid flip - before any lateral movement starts?
- too slow? casing does not impact the ejector hard enough - gets flipped, but not flung - then the bolt hits it on its way in?

Or something else all together?
 
twyeh said:
I noticed both users mentioned they have issues with the black export variants. Could this be a connection? Perhaps the the black ones are are made tighter and with diffrent QC standards for the civilian market, thus compromising its reliability compared to the green variants and original military cousins.

Just a theory.
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Definitely possible....

I got a hold of Marcus and one of the things he said was this: " I also know that they did some modification on the ejection port for export models which don't fire GP90 (swiss army .223Rem ammo)"

I'm not quite sure what he meant, but what your suggesting sounds totally possible
 
The only problem with that theory is that when he sets it to setting 2 it works ok. Setting 2 should make the gun cycle faster/harder, no?
 
*MALICE* said:
The only problem with that theory is that when he sets it to setting 2 it works ok. Setting 2 should make the gun cycle faster/harder, no?
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I think the case is hitting the charging handle, and the charging handle is knocking it back inside the chamber for some reason. Maybe it's going to slow and that is whats causing it somehow, who the hell knows, damnit it's frustrating
 
Steve Janes said:
Definitely possible....

I got a hold of Marcus and one of the things he said was this: " I also know that they did some modification on the ejection port for export models which don't fire GP90 (swiss army .223Rem ammo)"

I'm not quite sure what he meant, but what your suggesting sounds totally possible
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Do you still have the black one with you? Perhaps you can do a side by side comparison with your green one to see if there are any visual differences. And I assume your black one is the 1:10 twist version? How about your green one?
 
twyeh said:
Do you still have the black one with you? Perhaps you can do a side by side comparison with your green one to see if there are any visual differences. And I assume your black one is the 1:10 twist version? How about your green one?
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HA, no the black one has been with the shooting edge since May. Also I compared side by side and there is nothing that the naked eye could see different. I also took my classic green's piston, gas tube, and gas regulator and put them into the black special before I even sent it away and got no change (The shooting edge did this too with the same results)

And yes the black is a 1:10" twist, and the green is a 1:7" twist

If by some chance I can't get the rifle to start working again, I guess I'll have a bunch of spare parts for my classic green, I doubt anyone would want to buy a Swiss Rifle knowing it's bunged up, especially for any kind of money
 
Steve Janes said:
HA, no the black one has been with the shooting edge since May. Also I compared side by side and there is nothing that the naked eye could see different. I also took my classic green's piston, gas tube, and gas regulator and put them into the black special before I even sent it away and got no change (The shooting edge did this too with the same results)

And yes the black is a 1:10" twist, and the green is a 1:7" twist

If by some chance I can't get the rifle to start working again, I guess I'll have a bunch of spare parts for my classic green, I doubt anyone would want to buy a Swiss Rifle knowing it's bunged up, especially for any kind of money
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In this case, we have narrowed it down to your bolt and chamber. As as you have mentioned it sounds like an ammo/gas pressure issue (short stroking).
As crazy as it sounds, maybe your black 1:10 one requires GP90 to work properly? (harder brass, longer projectile, more pressure)

I am thinking that the 1:7 versions were tuned specifically for .223/5.56x45 and is potentially why your green one has had zero issues with the available ammo we can buy here.
 
Herron Arms and Gunsmithing has slow motion video capabilities for diagnosing and repairing problems such as this. I'd get in touch with them.

[youtube]LZWklZHMS7w&feature=plcp[/youtube]
 
twyeh said:
I am thinking that the 1:7 versions were tuned specifically for .223/5.56x45 and is potentially why your green one has had zero issues with the available ammo we can buy here.
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gp90 is designed for the 1/10 twist, not 1/7 which was added due to requests, not design.

its a wear issue, not a design issue
 
Oh come on Steve, just open up the ejection port a bit with the grinder and get back to the range already:p

Just kidding;), hopefully this gets resolved for you soon.
 
I agree with Tactical Sports. a high speed camera should tell you exactly what is going on and diagnose the problem. You just need to find someone that is willing to do that for you... Good Luck...

RDG
 
Steve Janes said:
LOL, I wish eh.ha:
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lol :D

I am curious about two things though, did you do a tilt test to check for any binding between the carrier and receiver?

With rifle upper assembled pull out charging handle disconnecting the carrier from the piston (put palm of hand over rear of receiver). Tilt rifle back and forth. It should glide smoothly back and forth and bolt should lock into lugs. Attach lower and repeat test.

Take your two rifles and swap the lower from the Green onto the Black. Test fire the rifle to see if the problem remains when using the other trigger group.

I mention this because mine has resistance once you attach the lower and does not glide as smoothly as with upper only. This is really noticeable if I leave the charging handle in and pull the bolt back under spring tension with lower attached.

Despite the binding I have not ever had any malfunctions in 3000 rounds and counting. This problem with yours sure sounds bizarre and hopefully gets resolved. Cheers.
 
J996 said:
lol :D

I am curious about two things though, did you do a tilt test to check for any binding between the carrier and receiver?

With rifle upper assembled pull out charging handle disconnecting the carrier from the piston (put palm of hand over rear of receiver). Tilt rifle back and forth. It should glide smoothly back and forth and bolt should lock into lugs. Attach lower and repeat test.

Take your two rifles and swap the lower from the Green onto the Black. Test fire the rifle to see if the problem remains when using the other trigger group.

I mention this because mine has resistance once you attach the lower and does not glide as smoothly as with upper only. This is really noticeable if I leave the charging handle in and pull the bolt back under spring tension with lower attached.

Despite the binding I have not ever had any malfunctions in 3000 rounds and counting. This problem with yours sure sounds bizarre and hopefully gets resolved. Cheers.
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I don't have the black one it's with the Shooting edge in Calgary and has been since May.

I didn't try it with a different lower and trigger group but I believe the edge did and there was no difference.

In regards to your tilt test, my bolt and carrier slide smoothly inside the upper, they always have, there is no binding of any kind or resistance.

Perhaps I misunderstood you there, but I believe what you are feeling as you pull the bolt back while you have the upper and lower together is the carrier sliding over the top of the hammer, it has nothing to do with binding, even when the hammer is cocked the bolt carrier comes into contact with the hammer and pressures the hammer spring when you pull back the bolt, the reason it feels so smooth when the lower is removed is because the hammer is in the lower and hence not there. Both my classic green and the black special felt this way.
 
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I have no idea what's going on here, but I for one, will not be letting my Swiss Arms see this thread, or even get close to it, in case it gets infected somehow......

First one, then two..... this is how it starts!

Call the CDC!
 
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