The Case of a Sickly Serpent

by
posted on July 12, 2022
Colt Diamondback with gun oil

While a thorough cleaning should be enough to eliminate stubborn rimfire brass from failing to eject from a .22 LR Colt Diamondback, soaking the chambers with a penetrating lubricant like Kano Kroil should remove any leftover firing residue and restore positive extraction.

I recently bought a 4-inch-barreled, blued Colt Diamondback in near-mint condition. I was thrilled when I picked up the gun, and immediately took it to the local range to see if it shot as good as it looked. I loaded it with six rounds of Eley Club ammunition that I had just purchased. When I shot the Diamondback, I was very pleased with how it felt in my hand and with the resulting group.

But, when I opened the cylinder and tried to extract the empties, they wouldn’t budge. I ended up using a wooden mallet on the ejector rod to remove the stuck cases. I decided to use a different brand of ammunition, also standard-velocity, which achieved the same results. The next thing I did was to put some oil in each chamber and proceeded to fire a full cylinder of ammunition. The cases came out much easier this time, but the next cylinder was as difficult to extract as the first.

What do you think is causing this and what should I do to keep this from happening in the future?

Tony S., Ridgewood, NJ

Congratulations on finding a Colt D-frame Diamondback in .22 LR. Most people who have them are reluctant to let them go.

Since Colt stopped production of the Diamondback in 1988—and your gun being in mint condition—most likely it was bought new and taken to the range. The new owner fired perhaps a box of ammunition through it, after which the gun was probably wiped down with an oily rag to protect the outside and put away without cleaning the barrel or the chambers.

Over the years, the firing residue left in .22 LR chambers will harden and solidify, making it difficult to remove the cases after they have been fired and expanded in the chambers. A secondary cause could possibly be that the original owner fired .22 Short ammunition in the revolver, leaving a carbon ring in each chamber, which would interfere with the insertion of run-of-the-mill standard-length, .22 LR ammunition.

There are several options that you can try, one of which will hopefully cure your problem. The simplest and easiest option is to use a new, tight-fitting, bronze-bristle brush and your favorite bore solvent to thoroughly scrub each chamber. Once the solvent has had time to work as suggested on the container, an additional pass or two with the brush followed by a few tight-fitting cleaning patches on a jag in each chamber to remove the solvent and firing residue will ready the Diamondback for testing. Keep running patches through each cylinder until they come out clean. On the range, insert a fresh cartridge into each chamber. They should seat fully with little resistance. Extract them with moderate hand pressure on the ejector rod. If this test is successful, load and shoot the gun with a cylinder full of fresh ammo, then test the extraction. All empty cartridges should extract with moderate hand pressure on the ejector rod.

If the cartridges are still sticking, clean the gun as before and treat each chamber with a patch saturated with a penetrating oil such as the popular Kano Kroil. After giving the penetrating oil time to undermine and loosen any remaining residue in the chambers, clean the chambers with a new brush and patches as completed previously.

Repeat the test procedure of inserting and extracting fresh cartridges, then firing a cartridge in each chamber. Follow that by testing the ease of extraction. 

In the unlikely event that extraction is still overly difficult, the chambers can be cleaned up with the careful use of a chamber reamer. Unless you are familiar with the use of such a device, however, rather than risk the possibility of a mistake, I would enlist the services of a qualified gunsmith to do the job.

In any case, cleaning the chambers, bringing them back to their original dimensions should restore normal operation and the pleasure in shooting your Diamondback.

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