Talk:Caliber conversion sleeve

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Contents 1 Questions 2 Two basic types? 3 Backup of article content 3.1 Start of inclusion 3.2 End of inclusion.

[edit] Questions

A couple of questions

• Is "caliber conversion sleeve" the proper name given that it doesn't convert the calibre (bore diameter) but rather the chambering (cartridge)? Perhaps if it's in common use the misnomer is fine
• Why is the article specific to .30 cal and .32 ACP? I thought you could get these gadgets for various different combinations of rounds, e.g. 22 LR in various centerfire cartridges etc etc.

--Russell E 01:00, 14 April 2006 (UTC)

Cartridge conversion sleeve, caliber conversion sleeve, and supplemental chamber are the only names I have seen for these devices. I have always heard them called caliber conversion sleeves, but this may not be the most common proper name. They are commonly sold today only for .30 caliber rifles to use 32 ACP.

They are not specific to .30 cal and 32 ACP, but this is the only such device pairing that I have seen in recent years. Added a 25 auto conversion that was evidently sold until roughly WW II, so they are not unique to .30 cal and 32 ACP.

I haven't seen one of these devices for 22 LR. There are kits sold to convert M1911A1 45 ACP to 22 LR for target practice. Likewise, there are AR-15 kits to convert them to 22 LR. However, all these 22 LR kits are complete slide, springs, and magazine swap out parts for semi-automatic actions. Unlike these, a supplemental chamber doesn't require any change of the barrel or magazine or springs, or any modifications to the bolt-action gun; you just load up the device and chamber it like any normal cartridge and shoot it.

If cartridge conversion sleeve or some other name is more common, we can certainly move the main article. Yaf 02:40, 14 April 2006 (UTC)

You can certainly get them in other combinations: see [1] .. however I'll take your word that anything other than the 32 ACP ones are uncommon. --Russell E 03:53, 14 April 2006 (UTC)

Interesting. But these appear to be chamber adaptors that stick in the chamber upon being fired. The cartridge conversion sleeve, on the other hand, does not stick in the rifle chamber, but is extracted each time to re-load another 32 ACP cartridge using the normal bolt-action extractor/ejector mechanism. No broken shell extractor is required for using the sleeve, unlike with chamber adaptors. Reminds me somewhat of the difference in flash suppressors and muzzle brakes :-) They, too, look much the same, but are treated differently by the BATF! Yaf 04:07, 14 April 2006 (UTC)

[edit] Two basic types?

I've see two types of conversions; the type covered in the article is cartridge shaped, and uses the firearm barrel to alter the cartridge used, but not the caliber. The other is longer, with a sub-caliber barrel that sits inside the firearm's barrel, and allows a change in caliber as well. This latter type is most common with shotguns, which use inserts to convert, say, a 12 ga. double to a 28 or .410, but I've also seen them available for other firearms--they work best with break opens. One I've personally used was a .22 Mag/.38 Special adapter for use in a T/C Contender, which was nice in that it didn't need the offset firing pin adapter needed in single firing pin guns, you just switch the hammer switch and use the T/C's rimfire pin. Truly odd are the rimfire inserts for shotguns, which may be designed with the insert barrel offset so the centerfire firing pin falls on the rim of the rimfire cartridge. Here's a source of just about any conversion you can imagine: http://www.mcace.com/Insertsindex.htm Here's a maker of short subgauge shotgun inserts: http://www.chambermates.com/ and here's Briley's full length tube sets: http://www.briley.com/index.asp?PageAction=VIEWCATS&Category=16 scot 19:31, 11 May 2007 (UTC)

[edit] Backup of article content

As per my discussion with Yaf (see here) I'm backing up the current article contents so I can restructure the article to cover the whole range of cartridge conversions. After the structure is done, this content can be merged back into the appropriate section(s).

[edit] Start of inclusion

is a device commonly sold for several 0.30-caliber-chambered rifles.[2] These devices enable the bolt-action rifles for which they are made to use 32 ACP cartridges in addition to the cartridges in the caliber for which the rifles are chambered. The caliber conversion sleeves resemble fired cartridge cases in the rifle calibers for which they are made, but are made of steel instead of brass, and have an opening where the primer would normally sit into which the 32 ACP cartridge is inserted, prior to chambering the combined 32 ACP round and caliber conversion sleeve in the rifle. No modifications to the rifle are required.

Three such 0.30-caliber rifles commonly have such caliber conversion sleeves available, for rifles chambered in the following cartridges:

• .308 Winchester, which use bullets that are 0.308 inches in diameter
• 30-06, which use bullets that are 0.308 inches in diameter
• .303 British, which use bullets that are 0.311 inches in diameter.

Caliber conversion sleeves work because the common 32 ACP bullet is 0.3125 inches in diameter, and will fire in practice in rifles with only slightly smaller bores than the 32 ACP bullet diameter, provided the difference in the rifle chamber size is properly compensated for with a caliber conversion sleeve.

There are limitations on the use of such caliber conversion sleeves. For example, the .303 British 174gr round normally exits the rifle muzzle at a velocity of approximately 2440 ft/s. When firing the 71 gr 32 ACP in the caliber conversion sleeve in such a rifle, the 32 ACP round will exit the muzzle at a velocity of only around 1100 ft/s. This reduces the effective range considerably, often to only 50 yards or so, and provides much less foot-lbs on target. The sights are additionally only approximately accurate, as the bullet mass (in grains) and the nominal rifle cartridge velocity have all been assumed in the calibration of the sights on the rifle. The caliber conversion sleeve is also typically capable of being loaded only one round at a time, effectively converting a repeater rifle into a single shot rifle.

Users also need to be aware that a squib may often result, as cheap 32 ACP FMJ cartridges may not have enough energy for the 32 ACP bullet to clear the barrel. This is especially dangerous if a high-powered rifle round is then loaded and fired after a 32 ACP bullet has lodged in the barrel.

However, the benefits when proper 32 ACP ammunition is used are that the recoil and noise of the rifle is greatly reduced, the price per round fired is much cheaper ($0.20/rd, or less, vs. $0.50-$1.00/rd), and, in a survival situation in which only a limited number of rifle rounds are available for hunting, the 32 ACP is certainly adequate for small-game hunting out to 50 yards. Hence, the caliber conversion sleeve can provide additional survival hunting rounds if one additionally carries a box or two of lighter 32 ACP cartridges in addition to carrying the usual rifle cartridges. In addition, it often becomes possible to use an indoor pistol range when firing 32 ACP cartridges in a hunting rifle chambered for a much more powerful 0.30-caliber rifle, opening up more firing range opportunities for practicing with powerful rifles in dense urban areas.

Caliber conversion sleeves for firing 32 ACP cartridges in 30-caliber rifles sell for approximately $16-$20 (2006) from major US gun parts distributors.

Occasionally, chromed or blued supplemental chambers for firing .32 S&W (0.315-inch diameter bullets) in 30-caliber rifles are also seen; these devices often date to the late 19th Century, and were made by Winchester, among others.[3] Similarly, there were also comparable devices sold for the 6.5 x 54 Mannlicher Schoennauer Model 1903 to reduce the round down to .25 auto that were widely available until roughly WW II. [4] The comparable devices for these older cartridge conversions are no longer commonly sold by major US gun parts distributors.

[edit] End of inclusion.

scot 14:16, 14 May 2007 (UTC)

OK, having looked over the old and new articles, I think that most of the content of the old article should probably go into a new section on using the conversions, and maybe bump the descriptions in the current article up a level and put them under a new heading titled "Design and construction" or the like. scot 15:47, 14 May 2007 (UTC)