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Joined: 06 Sep 2007 Posts: 154 Location: Kentucky

Asked this question as a response to another thread but didn't get any answer so I'll try again here. Do any of you know of any literature showing the effect on chamber pressures of using shell reducers such as chambermates ? I would think that given the lose seal of shooting a 20 ga shell in a 12ga borre the pressure would be reduced significantly. Thanks

Joined: 06 Aug 2009 Posts: 960

The chambers of any tube set (Chambermates included), are made to SAAMI guidelines. There will be no significant difference in chamber pressure between a shotgun with a tube set installed or a shotgun with no tubes. The design of the tube set either loose or tight in a specific barrel(s) also has no real affect on chamber pressure of a certain cartridge.

The peak chamber pressure is created within the first inch or so of travel of the ejecta. While pressure and velocity are affected once the ejecta has cleared the Chambermate, that initial pressure spike still happens.

I hope this helps.

Joined: 06 Sep 2007 Posts: 154 Location: Kentucky

Thanks, I kind of figured the actual chamber presure would be the same but as far as barrel pressure I wonder how much impact that has . While I am not advocating this would using a steel reducer and firing a 20 ga shell in a 12 ga damascus barrel contain the chamber pressure via the steel reducer and reduce the barrel pressure to a point where the gun could be used w/o splitting/damaging the barrel.

Joined: 06 Aug 2009 Posts: 960

For the actual barrel pressures, maybe some of the more mathematically gifted members could help you with that. You have to be able to calculate expansion ratios of the various powders and then figure the addition volume of the barrel. Shocked

I don't have a clue on how to figure that out. Laughing

Joined: 12 Sep 2009 Posts: 74 Location: las vegas NV

powderburn saw this on Gaugemates web site ( note not Chambermates )

www.gaugemate.com/docs/ballisticstests.pdf

Joined: 06 Aug 2009 Posts: 960

Nice link,

I am not much for strain gauge readings without reference loads, but in this case, that is probably as close as you can get, to the real numbers. They seem in the ballpark.