Letter Re: Firearm Chamber Adapters

Hi Jim,
I found an article in the latest issue of “The Backwoodsman” magazine that talked about using chamber adapters to employ different caliber ammunition in single shot, and over-and-under [rifle/shotgun combination gun]s like the Savage 24V. Here’s the [MCA Sports] web site mentioned in the article that sells the adapters: http://www.mcace.com/adapters.htm

It seems like a neat idea to have the capability to convert a firearm to shoot different types of ammo that might be scrounge during a long term TEOTWAWKI . Do you think there is any merit in investing in chamber adapters? Or would it be wiser to buy the different caliber firearms instead? Best, – Ron

JWR Replies: Many thousands of chamber adapters were made in the last century by the Marbles company. If I’m not mistaken, MCA Sports in Alaska now owns the tooling that was originally developed by Harry Owen, who advertised for many years in The American Rifleman magazine. The variety of adapters that MCA Sports produces is amazing. (Don’t miss the web page of the rifle and pistol cartridge adapters that they make for shotguns!)

I have been a proponent of using chamber adapters for non-tactical use, in single shots, double guns, and bolt action long guns, for many years. They are indeed a practical way to use scrounged ammunition for target practice, pest shooting, or small game hunting. One advantage is that they are generally quieter than shooting full power rifle cartridges. Here at the Rawles Ranch, we have four Harry Owen chamber adapters that I bought more than 20 years ago:

.30 Carbine adapter for .308 Winchester
.30 Carbine adapter for .30-06
.32 ACP adapter for .308 Winchester
.32 ACP adapter for .30-06

BTW, we don’t even own any guns chambered in .30 U.S. Carbine or .32 ACP, but we keep the adapters handy, just in case. These adapters don’t weigh much and they take up very little space.

It is important to mention that the point of impact will be different when using alternate cartridges. Do some target shooting tests with each of your guns. Following these tests, make note of the aiming offsets required. One good way to keep track of this is to note the aiming offset at 25, 50, and 100 yards on a business card and include it, along with a small packet of silica gel, in a heavy duty zip lock bag for storing each cartridge adapter. It is also a good idea to carry a short length of dowel stock in the same bag, so that you can push fired cases out the adapters, in the event that they get stuck. Luckily, this doesn;’t happen very often.

I have found that one piece adapters (such as those listed above) are particularly easy to use. However, the two piece adapters (such as those used for shooting .22 Long Rifle in a .223 Remington) are much slower and more cumbersome to use. When I tried using one of these with a Remington Model 7 bolt action in the field, I was always afraid that I would drop the adapter’s solid steel insert “plug” and lose it in tall grass. (The steel plug is designed to transfer energy from a center-fire rifle’s firing pin to a rim-fire cartridge’s priming rim.)

Another very handy adapter is the now-discontinued Savage “Four-Tenner.” These are long one piece chamber adapters that allow .410 shotgun shells to be used in a 12, 16, or 20 gauge shotguns. It is a clever design that transfers the force from your shogun’s extractor to its own shell extractor. These Savage “Four-Tenner” inserts can sometimes be found on eBay or on the various gun boards, such as GunBroker.com. (For example, here is 12 gauge model that is currently being auctioned on eBay. And here is a 20 gauge model.)

It may take some patient Internet and gun show searching to find some of the more obscure chamber adapters that are no longer produced. But even the old Marbles brand adapters come up for sale often come up for sale on eBay from time to time. For example, there is currently an eBay auction running for a .22 Hornet adapter for .223 Remington.