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

[BrianQ]

The finish types and associated problems are addressed in several of the Carbine Industry Committee Meeting minutes.

Parts undergoing a phosphate finish don’t need to be sand blasted for the finish to adhere. They just need to be bare metal free from any contaminants. Inland washed then grit blasted their receivers prior to phosphate coating but other manufacturers did not grit blast receivers. They just cleaned and phosphate coated them. In Inlands case they didn’t even grit blast the entire receiver either. That’s why Inland receivers that have not been refinished exhibit the two tone coloration on the lower portion of the receivers.

The finish on WWII era M1903s, 03-A3s, M1 Garands, M1911s, Saginaw Gear built M1919s, etc., was a phosphate finish. The GM at Saginaw Gear commented on the fact that the Parker-lubrite finish covered up minor scratches and machining marks. It also didn’t affect the operation of the weapon and provided better rust proofing.

[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.

[BrianQ]

Step 30 on Inland's List of Manufacturing Operations is Parco-Lubrite & Oil Barrel Assy .833 man hours per 100 assemblies.

[Tobor]

The finish types and associated problems are addressed in several of the Carbine Industry Committee Meeting minutes.

Parts undergoing a phosphate finish don’t need to be sand blasted for the finish to adhere. They just need to be bare metal free from any contaminants. Inland washed then grit blasted their receivers prior to phosphate coating but other manufacturers did not grit blast receivers. They just cleaned and phosphate coated them. In Inlands case they didn’t even grit blast the entire receiver either. That’s why Inland receivers that have not been refinished exhibit the two tone coloration on the lower portion of the receivers.

The finish on WWII era M1903s, 03-A3s, M1 Garands, M1911s, Saginaw Gear built M1919s, etc., was a phosphate finish. The GM at Saginaw Gear commented on the fact that the Parker-lubrite finish covered up minor scratches and machining marks. It also didn’t affect the operation of the weapon and provided better rust proofing.

Other than the Inland's, how would one determine the factory Parkerizing from the subsequent arsenal rebuild Parkerizing, especially if the Parker-lubrite was applied over existing scratches?

[mpd1978]

Look at the proof mark for signs of a 'through the finish' punch mark, also you can look at the rear sight dovetail staking for bare metal in the staking. Not always seen unless the carbine is in pretty good shape though.

Attachment 14454

[BrianQ]

Other than the Inland's, how would one determine the factory Parkerizing from the subsequent arsenal rebuild Parkerizing, especially if the Parker-lubrite was applied over existing scratches?

mpd1978 hit on a few ways. Those plus knowing how the individual manufacturers did thing helps As does examining known original examples.

[Tobor]

Look at the proof mark for signs of a 'through the finish' punch mark, also you can look at the rear sight dovetail staking for bare metal in the staking. Not always seen unless the carbine is in pretty good shape though.

Attachment 14454

Not to derail my own OP, but there seems to be a lot of contradictory info about the presence or absence and shape (chisel, punch) of stake marks on the dovetail rear sight mount on the receiver regarding the USGI flip sights. If there are no pronounced marks, does that mean that an adjustable ramp sight was never mounted per arsenal rebuild?

[Tobor]

Look at the proof mark for signs of a 'through the finish' punch mark, also you can look at the rear sight dovetail staking for bare metal in the staking. Not always seen unless the carbine is in pretty good shape though.

Attachment 14454

mpd1978 hit on a few ways. Those plus knowing how the individual manufacturers did thing helps As does examining known original examples.

Expert advice that is invaluable in making any determinations on collectible firearms.

[BrianQ]

Not to derail my own OP, but there seems to be a lot of contradictory info about the presence or absence and shape (chisel, punch) of stake marks on the dovetail rear sight mount on the receiver regarding the USGI flip sights. If there are no pronounced marks, does that mean that an adjustable ramp sight was never mounted per arsenal rebuild?

Nope

What some fail to realize is that not all the manufacturers staked flip sights when they were initially installed. Methods varied among the manufacturers that did stake the sights. When rebuild facilities upgraded the rear sight they may or may not have staked the new sight in place. The same goes for sights that were installed at a lower level. To further complicate things not all adjustable sights were staked with a round punch, some were staked with a chisel type staking device. In order to tell the difference you need to know what each type of staking looks like for the various types of sights.