Garand bolts that won't parkerize

I'm hoping to get other gunsmiths opinions on a problem I have run into twice this week now.

I parkerized about 12 rifles so far this week. Really been moving in the shop. Anyway, out of those 9 of them were military M1 Garands and the bolts on two of them would just not take the parkerizing.
I've only seen this maybe 5 times in almost 20 years or rebuilding these rifles and this week was two of them. I thought it was weird.
Both bolts were part of parts sets that came from the same place too which I thought was odd.

What I have always thought to be the case when a part would not parkerize was that it is either too hard for some reason or somewhere along it's life someone gave it a good dose of moly lube. Or some form of Moly. That stuff is near impossible to clean out of the metal but I've got a good way now to clean it and that wasn't the case.

My suspicion is that these bolts are too hard. Maybe the rifle they originally belonged to was in a fire. It was a combat rifle after all that saw a lot of service in god only knows what kind of conditions.
I tried to blast clean and parkerize each of these two bolts 4 times and still the same result. No color change at all. Also I noticed a shower of sparks flying off the surface while I was blasting them. Normally that only happens on hard chromed surfaces or something similar.

Any ideas? I recommended to both customers that we need to replace those bolts rather than risk using them.

I think I'd follow up on the replacement option until I could have the bolts inspected by a lab. Maybe they can be made to work, maybe not, but somethings not right for now. Far cheaper to avoid a potential problem then to deal with the after effects.

JK

Garand Bolts

Were made of 2 different steels.... Not counting Beretta or modern made...

Early was WD Steel No. 3312, 3.25% to 3.75% Nickle...
Later~ post March 42, was WD Steel 8620, .40% to .70% Nickle.. Right out of Hatchers Notebook....

Looks like early bolts will need a bit stronger Acid mix or temperature regimen to bite....

Recievers were made with 3 different steels, All with far less nickle than early bolts......

Far cheaper to research subject, then hire a laboratory....

And if doing a restoration on an early rifle, tossing an early Rare bolt is not exactly the smart thing to do.....

There are Garand Geeks out there, that can rattle off proper drawing numbers for serial number ranges..... On ALL the marked parts....

I've parkerized bolts like these before with no Problem. One of the ones with the problem is a well worn Winchester bolt identical to the one in my winchester. Mine parked just fine. I've got ways to parkerize that high nicle steel but it didn't work either. Anyway, Just for grins I went to a friend of mines shop yesterday and checked the hardness. They were off the C scale hard and he couldn't figure out how it happened either. He had a test block so I checked the cal on the tester and it was good.

Both of these problem bolts had considerable wear on them and would only headspace to a new short chambered barrel anyway. They were past the field gauge on the old barrels I took off so we're probably better off replacing them anyway.

There was a bad lot that Army pulled..

Had O-16 at top rear..

It was more than just nickle difference in the steels.

Totally different alloy....Early had Lot more Chromium also... 1.75 % vs .2 %

Later bolts were hardened to Rockwell C55 to C59 (on locking lugs and rear end of bolt). I have no info on early bolt heat treat.

Might check a known good late bolt on friends tester... should be close....