Blow out hole on percussion guns

Ok here you go. I don't have the pictures you really want; an overall view and close-ups of the breech and bottom. I can shoot those and post them Monday

I thought it was pretty cool too. Julia also had it mislabled. I've seen that with them before too. I bought a Luger one time that was supposed to have ONE matching magazine, and it wound up arriving with TWO. That's a BIG difference in value, which of course inured to my benefit. I contacted them afterwards and asked them if the seller wanted to break the trade, because I was buying something I thought was worth less than what was delivered (probably another $200 or so). The seller said no. He was ok with it as is. And my conscience was clear too

They listed this gun as a 40 calibre rather than a 40 BORE, which is 48 / 52 calibre lands/grooves. . Didn't talk about the mould either. There was a rather similar piece (with an original Purdey case rather than a substitute vintage case like this one) in the same auction that was estimated at $12,000-16,000 without the story. In slightly better condition too. I put in a way low but plausible bid on THIS gun (I didn't want to spend the other kind of money) and it didn't trade. After the auction I put it in again, and the seller hit my bid. Sometime you get lucky. The thing about Julia, and now Morphy is that their buyer's / seller's premiums are really expensive. And shipping too. I think it wound up costing me another $600 over my base price before I got it, which of course influenced my bid basis in the first place. In this particular case I did NOT call them to offer to break it, because my bid WAS based on it being 40 bore, and I suspected they just mislabled it.

Col. B - Lovely indeed.. Congrats.
I have a cased 40bore belted ball Double from Trulock & Sons. I couldn’t get it to shoot well until I was playing with it at Friendship (years ago) and thought “0,530 grooves, wonder if 54cal felt wads would help?”(3/8”). Well, both barrels converged and I was off to shooting smallbore Silhouettes. Although the Silhouettes were close, I had to aim well under - but I hit some of the little things and was thrilled to death.
Start shooting that piece and enjoy it.
You must come to Friendship and shoot the Double Rifle Match someday with us, soon. There are many originals still being shot there.



Note there are no proof marks or bore designation stamped on the bbls.. odd to me.

Gents, as I was lead to believe, the vent allows the air in the firing channel to vent
allowing the hot air/gasses/flame from the cap to more easily reach the powder, without compressing and heating the ambient air in the channel first.
It probably also eased the hammer blowback business.
I can also see the point of not pushing ambient air into the powder charge ahead
of the cap's flame. It might improve consistency of ignition. A guess.
Just lowering resistance to the flame front would be beneficial.
I built a Hawken with the patent breech, years ago, and had to go to a musket cap
nipple for consistent ignition. It was the convoluted flame path, I suppose.
I will try drilling a tiny vent hole and using a #11 cap.
Just as a result from this stimulating forum!
Thanks All!

I don't think Sam and Jake drilled vent holes in their rifles.

However, you have a problem with your rifle. You may find a benefit in providing a vent.

Feltwad said:

The vent main purpose is to aid ignition , when the cap is fired it draws in a small amount of air which result in a quicker ignition it has nothing to do with safety after the shot is fired or to allow air to escape when loading any compression of air will escape through the hole in the nipple
Feltwad

Click to expand...

I'm not quite understanding this. It would seem to me that when a percussion cap fires, it exerts pressure out rather out the vent hold rather than creating a vacuum to draw air in. Am I misunderstanding the concept here?

Gene L said:

I'm not quite understanding this. It would seem to me that when a percussion cap fires, it exerts pressure out rather out the vent hold rather than creating a vacuum to draw air in. Am I misunderstanding the concept here?

Click to expand...

Gene, I'm as confused as you are on this subject. Non-vented percussion rifles probably outnumber those with vents by about 99.999% to .001%. Those with no vents obviously work reliably or they would not have survived or still be in use.

Let me take a swing at this. In a normal load, the powder sits at the bottom of the chamber. There are air spaces between the granules no matter how fine they are, or how compacted. When the cap is detonated, the priming compound ignites and the expanding hot gasses are generally directed through the nipple and in to the powder column. Because the expanding gasses have to compress the existing gas in the powder column, those gasses from the cap do not expand as much throughout the column to ignite a whole bunch of granules at the same time. Thus, ignition is somewhat slower, and dwell time slightly longer.

With a blowout hole in place the original gasses between the granules can get pushed out the vent hole before the hot gasses get there and provide less resistance to the hot stuff through a slightly lowered chamber pressure for the ignition part.\

This is an experiment that calls for Pletch if ever there was one.

Hmmmm....so they figured this out in the 18th Century, early in the percussion age and at some point quit doing it? Why did they stop if it was so superior?

Without Pletch's emperical data we won't know how much of an ACTUAL advantage it provides. It might only be extremely small, but mostly marketed as a feature that (ultimately and really) catches more fishermen than fish. The new new new and improved model. It DOES take some labor an materials to do, but not THAT much.

I have a nipple on my rifle that has a hole drilled through it... would that be the same??

the hole in the nipple is to help the cap split when it is shot.

Fleene

Still leaving me bumfuzzled. We know not all the powder ignites instantly, it continues to burn and expand until the ball leaves the muzzle. I think that is how we want it. If it all ignited at once we would get a hammering effect and extreme pressures in the breech and barrels would only have to be a couple inches long. Drill yer holes. I'm happy without.

Zoomed in on older photo of the vent hole after an afternoon of shooting. Not much residue out of the small hole.

I imagine it worked good for the first shot or two then plugged up until thoroughly cleaned.

Kansas Kid:
I don’t believe it does as water comes out the vent holes when cleaning. Next time out, I’ll take some tape and see if it does after a dozen shots or so. Hope to be shooting some in s few weeks at Friendship.
I believe surviving pieces that don't have clogged holes are in the minority.

How are we going to get in all the stuff we need to do at Friendship??!!!

Fleener

Fleener- it will not be the 1st time I don’t get all the events in that I plan!
Bring your double rifle- the DR Match is on Monday.