Can anyone explain the Brass on this Receiver?

[bigbadbird]

Can anyone explain the Brass on this Receiver, at least I think it is Brass?
I changed this receiver for another and put a stainless308 barrel on it.
I did not like the look of it and was unsure if it was safe.
Has anyone seen one like this?

M1 Garand.jpg

Thank You

[pcox]

Looks like brazing material at first glance. If so, it would mean that the heat treat on that receiver is suspect.

[StockDoc]

that is weird looking, don't know what it is

[tmark]

Are you sure it is not some sort of oxidation of the metal like rust or some chemical stain?

[bigbadbird]

Looks like it was welded on, there is some porosity in the welds. Funny thing is that it is only on the out side.
Maybe it was bad castings and they filled it with welded material. You can see where they ground it flush.
Thanks to the internet I was able to re-barrel another receiver last night.
Used a pull thru Head spacing reamer to get the head spacing correct and took it to the range today.
Worked great so I am back up and running with dads old M1 Garand....
Going to keep the old parts for historic value but would sure like to know the story on the receiver.
Dad picked it up in the 60's and never fired it. Serial # is Springfield Armory 5451159
Does not look like it was a de-milled receiver. Looking forward to any good input about the ol beast and thanks for the replies.

[Crispy]

If you can tell us the maker and serial from the heel, along with drawing and heat lot from the leg, then we can almost certainly rule a welded demil in or out.
Chris.

[bigbadbird]

Serial # is Springfield Armory 5451159
There is also a Z10 A
and below that is F 5628291
The Barrel has SA F65354 48 12 54 MD 45

Thank for the input, hope this helps.

[Sunray]

Brass it ain't. Looks like brazing material to me too.

[Fred Pillot]

The spotting is in multiple areas of the receiver, so I don't see it being weld or brass. Looks more like something got splashed or dripped onto it. I had water from my washing machine leak onto some metal in the cellar once. The detergent left it crusty looking. Sand it to see if it cleans up. If so, get it beadblasted then reparked.

[Crispy]

Z 10 A is a correct heat-lot for that serial number range so, not a welded receiver.
If it is brass or braze material you should be able to "carve" a sliver from it with a pocket knife and see bright brass beneath the oxidized surface.

[bd1]

Reckon somebody tried to cook up a "project" M1C or M1D without the correct parts? Stranger things have happened. The general shooting public didn't hold the M1 rifle in particularly high regard for a long time after WW II.