Everything I've read has uniformly stated that when rust bluing a set of barrels, a vent hole in the bottom rib is essential because during the repetitive boiling process, the air trapped between the top and bottom ribs expands when heated to 212 degrees and the resulting pressure can pop a rib loose. But I've also noted that original condition Parkers don't have a vent hole like most other brands of vintage doubles, and wondered how Parker managed to rust blue its barrels, which presumably had to be done after both the top and bottom ribs were soldered in place.

Is it simply not true that a vent hole in the bottom rib is necessary for rebluing Parker barrels? Has anyone here ever tried to rust blue a set of Parker barrels without a vent hole and had the rib pop loose during the boiling process?

The boiling process is hot bluing not rust bluing. Rust bluing is a completely different process and others will give a lot better description but it is a slow rusting process in a box.


PDD

Those barrels need to be boiled or subjected to hot steam to change the red oxide to a black oxide before "carding".

So Parker barrels were rust blued and that is why there is no vent hole ?

PDD-
Hot bluing refers to the more modern process of immersing parts in liquified salts at temps over 300 degrees. Rust bluing involves coating barrels with multiple thin layers of red rust and boiling them between carding sessions. Rust bluing is the traditional method used for bluing soft soldered doubles that can not withstand the temps of the hot bluing process, as boiling water is only 212 degress F. But everything I've read indicates that venting of the air trapped between the top and bottom ribs is necessary to keep the pressure from popping a rib loose during the boilings. But Parker apparently didn't do that at the factory, as original condition guns don't have any vent holes that I have been able to locate. Perhaps the sighting bead hole on Parkers doubled as their pressure vent during the bluing process? I don't know. Hopefully someone else will and share that knowledge.

Justin, although I am not a gunsmith and have never personally blued barrels , I have a friend who is, and I have watched his process with Parker and other fine double barrels many times. The problem is not popping off ribs due to air expansion when boiling, the problem is seepage under the rib which would stay there and rust unless drained. For Meriden Parkers, there is no need to drill an extra hole after the barrels are done to drain them, the sight bead is removed during re-browning and and any seepage is drained through that hole. For Illion Parkers, they were made with a drain hole adjacent the barrel lump, an extra drain hole if you will, and that suffices. Some gunsmiths will drill a hole there in Meriden barrels and then plug it with a small lead shot pellet, then cold blue over it. A good gunsmith who regularly refinishes Parker barrels is Dale Edmunds at 816 444 2040, and conversation with him may be helpful.
Sincerely, Bruce Day ( Parker non expert)

Bruce,
Thanks for the great info. It sounds like Parker sighting bead holes tap into the "void" between the ribs. With most other brands of doubles, the bead hole is a dead end into the solder. The Parker bead hole alone would probably suffice to allow the quickly expanding gas to vent out when the barrels are dropped into boiling water. I don't have much Parker bluing experience, but I can tell you from rust bluing other brands that the gases expand violently and really bubble out that vent hole with force when the barrels are dropped into boiling water. I would be hesitant to boil any set of soft soldered barrels, no matter how well made, without a vent hole of some sorts to release the pressure on the ribs.

Also, it is generally not considered enough to only drain the water out of the void between the barrels because moisture and rusting solution salts can be left behind to cause problems. Most pros advise that the void be flushed out with a special water displacing oil, such as that sold by Brownell's, which isn't cheap. Its thinner than water and can easily be injected into the smallest hole with a large hypo needle. After being sloshed around thoroughly in the void, it is then poured out through the vent hole.

Speaking of vent holes in ribs, the older higher grade LC Smiths had the typical vent hole behind the forearm lug, but they threaded it and filled the hole with a small flush fitting plug screw, which looks quite nice.

The practice of drilling a vent hole in the bottom rib of a Parker for rebluing is so common that I have read several articles over the years advising that originality of bluing on Parkers can be easily verified by simplying making sure that there is no vent hole. That is obviously not true, as we can see with this subject D grade. But it does seem to indicate that most gunsmiths mistakenly think the new vent hole is essential.

Perhaps one of the pros like Brad B would be willing to post a thread and explain to us the ins and outs of rebluing Parker barrels without drilling additional holes. I'm sure that many of us would find it fascinating even if we have no intention of ever rust bluing a set of barrels ourselves.

Drilling a vent hole in the bottom rib is NOT necessary when re-rust bluing a set of Parker Bros barrels. Euss Bickel did a wonderful job on my 1898 Titanic barrels and he did not drill a vent hole. Pictures provided upon request.

Thanks Chilled.

Of course, we'd all like to see those pics posted!

The sighting pin hole thing got me curious, so I removed the bead from a set of beat up original length (shooter grade) GH barrels that I intend to reblack some day. I attempted to inject some acetone down the sighting pin hole to see if it accessed the void between the barrels. It clearly does not. The void between the barrels of pre-Remington Parkers appears to be sealed. Which would seem to indicate that Parker Brothers rust blued their barrels without any venting. They apparently had more faith in the workmanship of their soldering than most (if not every) other American gun maker of the period.

Of course I'm just speculating here, but it would seem logical to conclude that if the solder is still air tight and strong, no bubbling will be observed when the barrels are submerged in near boiling water. If the soldering has lost its air tight seal over the decades, that would be easily detected by escaping air bubbles, and a vent hole would then be necessary in order to drain out the water at the end of the bluing process and flush it with water displacing oil. So perhaps the answer is simply that if you are fortunate enough to have a Parker with soldered seams that are still air tight, you won't need to have a vent/drainage hole drilled.