Why Were Carbines Factory Parkerized When ALL USGI Thompsons' Were Factory Blued?

[Tobor]

You can see that the majority of carbines were parked just by looking at original examples throughout carbine production. The early carbines were blued but since the finish didn't hold up well to the salt spray test a phosphate finish was adopted. The phosphate finishes didn't fare much better to the salt spray but it was an easier process. And yes there is documentation confirming the type finish applied.

BrianQ,
Could you refer me to the M1 Carbine reference where this is explained?

While there were only two entities manufacturing TSMG's during WWII, Savage and Auto Ordnance, and 10? entities manufacturing Carbines, it is odd that there wasn't a standardized finish that would be utilized for all factories for USGI small arms. Many USGI TSMG owners still believe their Parkerized Thompsons' sport the factory finish.

Phosphating is the same as Parkerizing (which was a proprietary process of the Parker Rust Proof Company just as " Du-Lite" is the name of a refinishing product) and would require that the parts be sandblasted first or the finish won't adhere. This would be a time consuming process and the parts would require protection from rust while awaiting the phosphating. There is no prep required for bluing other than the parts being clean. To machine a part, and then blue it is much faster than Parkerizing. The time savings in the middle of a war would surely tend to favor bluing, especially when the factories are already set up for bluing. The TSMG was subjected to the same government mandated proof testing, and yet they were shipped out blued.

The USGI TSMG was either blued right over the raw machined steel or sand blasted and then blued.

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[INLAND44]

BrianQ,
Could you refer me to the M1 Carbine reference where this is explained?

While there were only two entities manufacturing TSMG's during WWII, Savage and Auto Ordnance, and 10? entities manufacturing Carbines, it is odd that there wasn't a standardized finish that would be utilized for all factories for USGI small arms. Many USGI TSMG owners still believe their Parkerized Thompsons' sport the factory finish.

Phosphating is the same as Parkerizing (which was a proprietary process of the Parker Rust Proof Company just as " Du-Lite" is the name of a refinishing product) and would require that the parts be sandblasted first or the finish won't adhere. This would be a time consuming process and the parts would require protection from rust while awaiting the phosphating. There is no prep required for bluing other than the parts being clean. To machine a part, and then blue it is much faster than Parkerizing. The time savings in the middle of a war would surely tend to favor bluing, especially when the factories are already set up for bluing. The TSMG was subjected to the same government mandated proof testing, and yet they were shipped out blued.

Why are you digging in your heels on this, questioning decisions and processes of nearly 70 years ago? It is what it is. One of the early carbine manuals had the phrase 'a peculiar shade of neutral gray' describing the obviously Parkerized finish. Yes, we know that Parkerizing is Zinc Phosphate.

[Tobor]

Why are you digging in your heels on this, questioning decisions and processes of nearly 70 years ago? It is what it is. One of the early carbine manuals had the phrase 'a peculiar shade of neutral gray' describing the obviously Parkerized finish. Yes, we know that Parkerizing is Zinc Phosphate.

Pondering the how/why/where minutia is consistent with owning collectible firearms. As there appears to be disagreement on whether all Carbines were factory blued and later parked, or only the early 1942 Carbines were blued and later parked, the facts regarding this aspect of the USGI M1 Carbine doesn't seem to be widely disseminated in the books on the subject.

I imagine that this early manual was not referring to the Winchester/Inland Carbines, yes?

[usgicollector]

There is no disagreement, Inland alone made over 1.5 million that were parkerized/phosphated. Most of the carbines were parked except the couple hundred thousand at inland and a few of the early winchesters. The first underwoods which were the third maufacturer to obtain mass production were parked with some blued parts. I quote from WAR BABY !pg 111"Interestingly the front and rear sights were blued on all of these carbines, in contrast to finish of the other parts, which were of a grayish color" The guns they are talking about in that sentence were the five carbines from the first five hundred produced for their initial production testing. Also in WAR BABY !, some of the makers order of operations are given for the receiver,standard products step 84 on the receiver is parkerize. For what it is worth step 51 on the bolt calls for dulite. If someone is telling you otherwise they may be misinformed. Don't believe all that you read in sales ads either, remember they are selling and we all know how gun salesmen can bend the truth.