Strange vent hole in percussion shotgun by Stevens of London

[Ironoxide]

Hi,

Can anyone say why some of the antique muzzleloaders have those vent holes as shown on the picture below? Some may be a remnant of a past flintlock conversion, but when a whole breech is replaced, why make a hole like this in the new one? Is this to lower breech pressure?

Could someone shed more light on this and point me in the direction of some books/texts that talk more about how a decision was made to make those vent holes or not in the past, please? Was this common thing?

Also, I see guns like this popping up for sale at pretty low prices. How much hassle are those little holes when shooting? Can they sting someone standing at the side of someone firing a gun next to a person?

This is a picture of one:

 

[Grenadier1758]

Those little holes are a design feature with the intent to speed the rate that the heat from the percussion cap gets to the main charge. There is anecdotal evidence that ignition is improved. The little hole can be blocked by fouling when the bore is wiped between shots. The flash through the relief ho,e is no worse or distracting than the flash from the touch hole on a flint lock. That relief innovation seems to be common on better quality British shotguns and rifles. The relief vent is uncommon on American rifles and shotguns.

Hot Shot nipples have the relief vent drilled in the cone of the nipple to create a hotter jet of flame to better ignite the substitute powders.

There is a long thread with lots of debate on this subject on the forum. Someone may post a link to that topic.

 

[Larry Akers]

When the percussion cap explodes the flame front from the cap compresses the air ahead of the front, possibly preventing the flame from reaching the main charge. The little hole relieves that pressure and makes the gun more sure-fire. At least that was the rational. As Grenadier said it is prevalent on high end British guns. Yes, someone standing to the side can be stung by the blow-out from the vent.

 

[Zonie]

There is a topic on the forum that goes all thru the subject of these vent holes on a Percussion gun.
Follow this link to read what others said about it.

https://www.muzzleloadingforum.com/...every-shot-with-out-fail.113363/#post-1545352

 

[52Bore]

Not strange - very common on high quality early British Percussion shotguns..

 

[Bad Karma]

Hi,

Can anyone say why some of the antique muzzleloaders have those vent holes as shown on the picture below? Some may be a remnant of a past flintlock conversion, but when a whole breech is replaced, why make a hole like this in the new one? Is this to lower breech pressure?

Could someone shed more light on this and point me in the direction of some books/texts that talk more about how a decision was made to make those vent holes or not in the past, please? Was this common thing?

Also, I see guns like this popping up for sale at pretty low prices. How much hassle are those little holes when shooting? Can they sting someone standing at the side of someone firing a gun next to a person?

This is a picture of one:
View attachment 14335

They might sting a neighboring shooter. I often shoot alone so for safety sake you should probably send any such pieces to me... Why do I never see them popping up at low prices?

 

[Many Klatch]

That hole also allows the flash channel to blow clear after each shot. My wife had a percussion rifle that tended to clog up the flash channel. I put a 1/16" hole in the clean out screw on the bolster and ended that particular problem