SEI metric Gas Lock Front Sight - M305

Skullboy said:
I wouldn't use aluminum for a gas lock sight. I don't think a Alloy GLFS would be nearly as durable as the steel ones and stand up to abuse.

SKBY.
Click to expand...


If these two metals are together for long with moisture, you may experience galvanic corrosion and foul the threads.
 
I don't anticipate needing another; however when the new ones get made, have a few done with the threads timed 180° off. Not too many, maybe 5% of the total. I remember when we got then from Slavex. There was me, and at least one other person that needed a different timing. I think there must be a few 'Rinco barrels that got put into the barrel profiling machine upside down.
 
Skullboy said:
I wouldn't use aluminum for a gas lock sight. I don't think a Alloy GLFS would be nearly as durable as the steel ones and stand up to abuse.

SKBY.
Click to expand...

Good point. I was thinking the tough stuff like 7000 series, but steel would be superior in any case. That stuff is no easier to machine than steel anyhow. Thanks for the advice.

Moot point though as I still don't have the technology to thread the steel or aluminium to that wacky size. I think it is a job best left to a machnist, not a backyard bubba like me.:D

Zorak said:
If these two metals are together for long with moisture, you may experience galvanic corrosion and foul the threads.
Click to expand...

I obviously wasn't thinking of that either, thanks. As clean and dry as you try and keep your firearms, condensation will always be there...



Come on Ron, get some of these made so I don't screw my rifle up trying to homebrew a replacement....
 
Zorak said:
If these two metals are together for long with moisture, you may experience galvanic corrosion and foul the threads.
Click to expand...


Hey Zorak, do you get galvanic corrosion between steel and aluminium? Outside my experience here, I know you can get it with zinc/bronze/brass and steel.....is it any dissimilar metal? (if so good point, but I think if you shot a lot you'd flame cut it off before this would be a problem, it would be a big issue if it was more of a hunting rifle though!)
 
I couldn't find anything pertaining to rifles but this is a run down on galvanic reactions.


Galvanic Corrosion
All corrosion is essentially galvanic. The cause of the corrosion is usually the environment and the metals themselves.

Each metal has a small inherent electrical potential; it's what allows you to make batteries out of potatoes. The electricity does not come from the potato, but from the difference in potential of metals that you stuck into it - like copper wire and an iron nail. All metals have a particular potential and a ranking of the metals from the most passive (lowest potential - platinum), to the most active (highest potential - magnesium), is shown below. See Table 1.

Table 19- Galvanic Series in Seawater

Magnesium
Zinc
Aluminum (pure)
Cadmium
Aluminum lloys
Mild Steel and Iron
Un-passivated Stainless Steels
Lead-Tin Solders
Lead
Tin
Un-passivated Nickel Alloys
Brass
Copper
Bronze
Silver Solder
Passivated Nickel Alloys
Passivated Stainless Steels
Silver
Titanium
Graphite
Gold
Platinum


Place any two metals in wet contact with one another and a galvanic reaction takes place. The more active metal of the two will dissolve (ionize). The farther apart the two metals are on the galvanic series, the greater the difference in potential and the stronger the dissolution will be. Size also makes a difference - if the more active piece of metal is smaller than the more passive, the corrosion will be enhanced but if more passive metal is smaller than the more active, the corrosion will be diminished.
 
Cocked&Locked said:
...(...but I think if you shot a lot you'd flame cut it off before this would be a problem, it would be a big issue if it was more of a hunting rifle though!)
Click to expand...

after firing a few hundred rounds without cleaning, there was only the slightest smudge of carbon in the joint between my gas lock and the cylinder.
Are you sure there is enough high velocity and high temperature gas to cause any erosion?
 
Splatter said:
after firing a few hundred rounds without cleaning, there was only the slightest smudge of carbon in the joint between my gas lock and the cylinder.
Are you sure there is enough high velocity and high temperature gas to cause any erosion?
Click to expand...

Yes, its not the carbon but the temperature and velocity, like flame cutting on a revovler top strap. I can't think of any weapon where aluminum is used in a gas handleing system......

Thanks for the information on galvanic reactions, looks like Zorak was right on the money, AL is right up there on the table and would go fast!
 
I understand it isn't the carbon that causes the gas cutting, I was using the carbon as an idicator that only the very tiniest whisps of gas escapes between the cylinder and the lock, on my rifle anyway.
 
Splatter said:
I understand it isn't the carbon that causes the gas cutting, I was using the carbon as an indicator that only the very tiniest wisps of gas escapes between the cylinder and the lock, on my rifle anyway.
Click to expand...


Sorry, misunderstood your intent:redface: . I'd still as soon have steel. If you cut a dovetail in the aluminium or put wings on it, they're going to be very susceptible to damage unless you make the wings/ring beefier, and be very carefull how you tighten the sight, and even then the dovetail will get chewed. You could put a steel base onto the aluminium ring, but then you might as well make the whole thing steel and your back where you started....
 
Last edited:
Cocked&Locked said:
Hey Zorak, do you get galvanic corrosion between steel and aluminium? Outside my experience here, I know you can get it with zinc/bronze/brass and steel.....is it any dissimilar metal?
Click to expand...

Yes, but some metals are quicker to do it than others. When you see galvanized steel, that's zinc that has been deposited on the surface through this process. The steel will erode the aluminum by pulling small particles of it through the water and affix it to the surface of the steel.

http://www.ocean.udel.edu/seagrant/publications/corrosion.html
 
Last edited:
Zorak said:
Yes, but some metals are quicker to do it than others. When you see galvanized steel, that's zinc that has been deposited on the surface through this process. The steel will erode the aluminum by pulling small particles of it through the water and affix it to the surface of the steel.

http://www.ocean.udel.edu/seagrant/publications/corrosion.html
Click to expand...

cool, I learned something new! I know if you overtighten aluminum threads on steel, the try to become one......(great things to discover when you buy a used upper, the guy before you never heard of anti-sieze or a torque wrench.....:puke: )
 
Will these GLFS work with both the standard 22" barrel and the shortened 18.5" barrel?? I seem to recall there being a difference...or maybe I am just having a stupid moment...:onCrack:
 
mdbuckle said:
Will these GLFS work with both the standard 22" barrel and the shortened 18.5" barrel?? I seem to recall there being a difference...or maybe I am just having a stupid moment...:onCrack:
Click to expand...

The GLFS will work with a fixed Navy Sight. Or, if we are talking dovetail versions, you have to get the proper height if you intend to reuse the standard Norinco 22" front dovetailed sight.

See the discussion here for more of this potentially confusing discussion:

http://www.canadiangunnutz.com/forum/showthread.php?t=128039

:)
 
You must log in or register to reply here.
Back
Top Bottom