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Old September 10, 2019, 22:59   #6
Arrogant Bastard
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FALaholic #: 96
Join Date: Jul 2000
Location: Surprise, AZ
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Originally Posted by 12v71 View Post
Nice save. Just curious, are the center pics after Parkerizing? Was wondering if the mottled appearance was from heat zones similar to heat treat lines on a parked FAL trigger housing.
No, it's because one of the welding rods I used was ER308 (stainless) instead of the ER70S (carbon steel) that I thought I was using.

Not a problem, but it can't be undone. I generally use the stainless for weld repairing hardened pieces, such as heat treated 4130 or 4140, as carbon migrates to the heat and can fracture if too hard at the joint. You will note two piece FN bolt carriers such on the M249 and and the FNC have the two parts welded with stainless.

I don't profess to be a master welder, but I do note when manufacturers choose stainless, so I copy them. I also have an example of a factory weld repair on the bridge over the chamber on an IMBEL - welded in stainless.

These two types have served me well for most jobs. It's also the reason I opted for the later black finish instead of Park.

T. Mark Graham, Master Gunsmith
Arizona Response Systems, LLC
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