doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Sleeving down a gauge (aka Chamber Sleeving)

Discussions on my nitro proved WR on another thread got me to thinking and making some calls to gunsmiths. Let's say I have a 12 gauge gun with questionable barrel strength. There is a procedure for making a chamber sleeve by removing the forcing cone and deepening the rim rebate to 1/4 inch deep. Then an insert is turned to fit and locktited in place. The insert is then chambered to 16 gauge. There is the benefit of the extra steel in the chamber and the pressure drop when the 16 gauge charge is fired into the 12 gauge bore. The velocity of the shot will drop as the result of the charge expanding into a larger volume. Are there any data on the effects on chamber pressure the force on the gun, shot velocity and pattern density?

Another example would be a gun with excessive barrel wall thickness. The barrels could be reamed to a larger diameter, effecting making a 12 gauge with an 11 or 10 gauge bore. What would the effects on the pressures, etc in that case?

The whole conversion requires work to the extractors/ejectors also. Briley tubes due essentially the same thing and include the ejectors.
What you are describing seems like creating a carrier gun for skeet in which all the barrels are tubes. The main complete assembly is bored out and all the tubes are weighted to give the gun the same weight with every set. The gun can't be used without a tubeset.

To 20 gauge

https://www.briley.com/p-52190-companion-drop-in-20-gauge-tube-set-standard-weight.aspx

I had considered briley tubes but I wouldn't want to add a pound to the gun weight. I don't think a sleeved chamber would add more than a couple ounces.

Conventional chamber sleeving is pretty much only done to guns that are unsafe to use as is, due to pitting, other wear, or metal removal in the chamber/forcing cone area. I ran into a 12 that had been chamber sleeved down to 20 at a show years ago and had a nice discussion with Kirk Merrington about the procedure, a few days later. I’d never seen it prior.

As I recall, generally the gun will be safe to use again, and the plastic wads seem to seal just fine, and patterns are good. Value takes a hit, but, you have a gun you can use again. I don’t recall anything about Loc-Tite in the discussion with Kirk, but, it was a long time ago.

The procedure seems more geared to guns that are at end stage of usefulness, I doubt anyone does this to a gun sans issues of thin barrels that lead to questions of safety.

Best,
Ted

I believe that a ten to twelve gauge chamber sleeve can be used without an extractor modification. I don't know about other size conversions.

12ga to 20ga sidekicks? Adds 8oz per pair and the weight is between the hands.

Just a thought.

Briley will do this, at least according to their website. Gauge to gauge or down one gauge in the case of damaged chamber. I once had a Parker trap gun with the left barrel being rechambered due to a bulged chamber. I sent it to Briley, thinking it needed fixing, and they sent it back saying the gun had been fixed. You cannot tell an insert has been placed in the chamber but you could see a slight bulge on the outside of the chamber from the original incident. Cyril Adams started doing this from 10 to 12. The result being an overbored 12. I have a 10 with a tight chamber that would make a nice heavy 12. Steve Barnett had a couple of the Cyril Adams sleeved guns a few years back. Go for it

you might read Bob Brister's "Shotgunning the Art and Science". He details having a barrel bored out taking a 12 ga to maybe an 11 ga and the results. Also you might be able to find a set of chamber mates. Not made by Briley but will take a 12 to 20 without adding much weight at all. They are maybe 4 inches long. Also you might contact John Hosford, he is a wealth of info and can help with what you are contemplating.

I own one of Cyril Adams 10/12 chamber sleeve guns. It started out as a 10 ga. Remington fluid steel barrel hammer gun that he chamber sleeved to 12 ga. and restocked for live bird competation. 30 in. barrels and 8 lb. weight. The patterns are great and the ballince is wonderful. Brileys and others can do the job.