Blow out hole on percussion guns

Discussion in 'Percussion Rifles' started by Col. Batguano, May 7, 2019.

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  1. May 8, 2019 #21

    S.Kenton

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    I too have read that this was a safety device, I’ll see if I can’t dig up my source..
     
  2. May 8, 2019 #22

    arcticap

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    One question that I ponder over is whether the vent can cause smoldering powder particles to not be extinguished as rapidly after the shot due to the introduction of air.

    I once read in a TC manual to leave the hammer down on the nipple after firing to help extinguish smoldering powder, in order to help deprive it of oxygen.
    Even I don't strictly follow that practice and do put the hammer on 1/2 cock before ramming [but after waiting].
    I could see that the vent could help powder flow better into the powder chamber during ramming just as many often practice today.
    But that can also be accomplished by letting air escape through an open nipple hole.
    So while the vent might aid powder flow and ignition in that respect, could having one also be considered more dangerous due to letting air come into contact
    with smoldering particles and prolonging their ability to burn?
    I suppose that more air could also help smoldering particles to both burn and extinguish faster, but the introduction of air wasn't what TC recommended at all.
    TC recommended that the air inside of the breech be cut off after the shot to help promote safety when dropping the next powder charge.
     
    Last edited: May 8, 2019
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  3. May 8, 2019 #23

    Col. Batguano

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    Here they are Purdey lock right 1.jpg Purdey lock left 2.jpg
     
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  4. May 8, 2019 #24

    Feltwad

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    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
     
  5. May 8, 2019 #25

    arcticap

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    The vent "may" aid ignition by drawing the hot gas upward [toward the powder] to escape through the vent, but I'm not sure how it would draw cool air inward to the breech.
    The reason for this logic is that if the percussion cap releases a certain volume of CC's of hot gas, the pressure inside the breech would be
    slightly greater than outside of the breech.
    Wouldn't the higher gas pressure inside the breech want to escape to equalize pressure?
    The higher pressure probably won't go backward out of the nipple hole, but I don't know if any of this gas has enough time to travel much farther out toward the vent
    before the powder ignites either.
    At least some of the cool breech air "may" be forced out of the vent until it turns hot by the powder ignition.
    Some people may know the physics involved but I'm only guessing.

    Too bad we can't ask Purdey why those vents were installed, unless it was written down somewhere. ;)
     
    Last edited: May 8, 2019
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  6. May 8, 2019 #26

    arcticap

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    Edit: Sorry, maybe the Samuel Nock patent recorded something about the reasons for the vent and how it works.

    Col. Batguano, That's a beautiful gun.
     
    Last edited: May 8, 2019
  7. May 8, 2019 #27

    Woodnbow

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    I can remember being advised to hold a roundball in my hand and cover it with powder for an appropriate load. There are lots of old wives tales out there...
     
  8. May 8, 2019 #28

    52Bore

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    This highlighted statement is completely wrong. PT is nearly as soft as lead and there no way they could easily unscrew, especially when fouled..
    I’ve only seen under the PT 1 time on an original British piece - there was a small screw with a hole thru the center (like a #8), the counterbore for the PT disc (diameter of about 0.250”) was only about 0.040-0.060” deep. It was relieved/undercut and the PT disc was swaged into place.
    PT, being a precious metal was not put on every gun by every maker, typically only on the Best British work.
    Yes, Col. B that’s a beautiful looking piece.

    972C07D9-3386-4FE7-B56A-6F12EC2575AF.jpeg
     
    Last edited: May 8, 2019
  9. May 8, 2019 #29

    Rat

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    Seems like if it was a safety concern, that it would be more easy to just reduce the powder charge. Or increase the wall thickness of the barrel. (and we know that's not the case anyhow) Also seems that if proofing a gun was known, that the early cap guns would have been "proofed", and it would have been known if they were weaker than a flintlock, or easy to blow up. "Safety Valve", or "blow out plug" does not really make sense to me.

    Perhaps early caps were weak, and needed all the help they could get? Musket caps solved the problem for military guns? And now, with our hot caps we use, a vent is un-needed.
     
  10. May 8, 2019 #30

    Rat

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    I was told the same thing, except to turn around, counter-clockwise, three times, then click my heels together, and repeat several times, "there's no powder like black powder". For some reason, I've never been able to kick the habit.
     
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  11. May 8, 2019 #31

    arcticap

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    For the sake of accuracy, platinum is considered to have medium hardness.
    On the BHN scale, it's number is 392
    The BHN of Aluminum is 245.
    The BHN of iron is 490.
    The BHN of zinc is 412.
    The BHN of lead is 38.3 which is not anywhere close to platinum's 392.--->>> https://periodictable.com/Properties/A/BrinellHardness.v.html

    On the Mohs scale of mineral hardness, platinum has "intermediate hardness".--->>> https://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness

    "Intermediate hardness
    Hardness Substance or mineral
    2.5–3 gold, silver, aluminium, zinc, lanthanum, cerium, Jet (lignite)
    3 calcite, copper, arsenic, antimony, thorium, dentin --->>> [copper must be a mistake because it's BHN is much higher than platinum]
    3.5 platinum
    4 fluorite, iron, nickel"

    How do we know that the vent wasn't a platinum alloy or another piece of metal coated with platinum?
    Did you manage to remove your vents or are they always left in place?
    Even if the vents are not designed to be removed with a turnscrew, how were they inserted and manage to stay in place for so long?

    You may [or may not] be right about the turnscrew, but IMO not accurate about comparing the hardness of platinum to being nearly as soft as lead.
    Platinum is much harder than aluminum and its hardness is in between aluminum and iron.

    P.S. Clicking on an individual element in the elements chart listed above will reveal its hardness on 3 different scales.
     
    Last edited: May 8, 2019
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  12. May 8, 2019 #32

    BlackHillsBob

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    put them on many guns, always improves ignition. doesnt cause great bodily damage. put a finger over the vent once by mistake and it was a sharp snap that didnt ruin my finger, just woke me up. so many try to make nothing of this but it works and was on many high end guns of days gone by. plan on building a crocket rifle soon, it will be on their also.
     
  13. May 8, 2019 #33

    52Bore

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    I have drilled a lot of 99.9% pure PT (I special order it from Stuller), Lead and Pb alloys, Copper and alloys as well as many other metals over the years on my lathe. A small drill bit (#70) will not only drill in a finger chuck, but will also grab and snap off much like in lead and copper and other very soft metals.
    The slot in the vent was not for a turnscrew or they’d be buggered up from such, like slotted steel screws we see- but it just isn’t seen on good surviving pieces.
    The PT (plug/disc) is installed the same as Gold or Silver by an engraver.
    IMO - the hole was leftover from the Flint era. Percussion evolution of the PT hole itself became obsolete/not necessary - yet the PT plug remained on many of the British Best ML arms.
     
    Last edited: May 9, 2019
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  14. May 8, 2019 #34

    Woodnbow

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    I’ll give it a shot! “Now where did I leave my red Tony Llamas?”
     
  15. May 9, 2019 #35

    dlidster

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    This appears to make the most sense. The hole was there not for a purpose but out of FL barrel makers' habit.
     
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  16. May 9, 2019 #36

    arcticap

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    If you read about the history of platinum and minting coins, most British platinum was obtained from Russia dumping coins that were minted from impure platinum that came from the Ural mountains which unintentionally contained other noble metals like indium and palladium. Attempts to mint British and Russian platinum coins presented problems due to its hardness. It was considered to be very difficult to work and made for poor reliefs.
    It's 60% heavier than silver and won't melt in a fire like gold or silver.
    Platinum was so heavy that the Spanish alloyed it with copper and then gold plated it to match the weight of gold which was also used for counterfeiting British Farthings
    Platinum basically only came from South America and Russia in those early days..--->>> https://en.wikipedia.org/wiki/Platinum_coin https://en.wikipedia.org/wiki/Platinum_coin

    Platinum seems to be a rather tough and extremely dense metal much like the zinc core of US pennies in hardness.

    What are pennies composed of?
    They are composed of an inner core alloy of 99.2% zinc and 0.8% copper with an outer plating of pure copper, for an overall composition of 97.5% zinc and 2.5%copper, and are minted on blanks produced for the Mint by an outside manufacturer (Jarden Zinc Products).--->>> https://en.m.wikipedia.org/wiki/Penny_(United_States_coin)#Composition

    As tough as platinum is, other than the fact that it's heat resistant,it's still probably not as strong as the barrel itself.
    So it seems that the vent could burst before the barrel would if placed under stress. But apparently it was strong enough to withstand proof testing.
    Why didn't they make the vent out of the same material as the barrel when only the vent hole needs to be lined with platinum? Or did they and we don't know about it?
    Thank you. With your help I learned some new and interesting things today.
     
    Last edited: May 9, 2019
  17. May 9, 2019 #37

    52Bore

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    We will never know what % of PT the old makers used.
    I know this is slightly off topic. I do know that in nipples - the higher the PT content - the longer it last before burning out. PT melting point is very high, over 3k. It resist erosion as well compared to other metals - and they knew this in the 1800’s, just blows my mind.
    Since were on PT and originals and what the makers did- here is an original I cut in 1/2. The cone was already chipped when I got the gun - EM Reilly Sporting Rifle.
    Photo was published in 1993 GunDigest along with an article on LRML.
    Thanks for the discussion.
    FF9E0F5E-34D5-454C-ACF0-1247ED455082.jpeg
     
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  18. May 9, 2019 #38

    52Bore

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    Took the liberty and email an old correspondence (Ian Jackson, now nearly 80) in England who used to work in the gun trade, his last employer was Westley Richards.
    Here is his reply to my question as to the purpose of the hole.

    They are usually only found on more expensive guns, and as far as I understand their purpose was to minimise hammer lift when fired, as well as supposedly helping to reduce the amount of fouling within the communication channel. The first I can sort of accept as being possible - but the second not so much. So probably more 'bling' and hype than being essential for the shooting of the gun.!


    As platinum became more expensive, plain un-vented communication channels became more usual, and once breech-loaders appeared in the '60's vented guns were only ever to be seen on better m/l guns. Rifles were the ones that had screw-in vent screws, due to their much higher breech pressures etc. Whether they were ever routinely removed for cleaning the communication channel is open to debate, as they are often seized solid and best left alone.!
     
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  19. May 9, 2019 #39

    Zonie

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    Very interesting, 52Bore.
    Be sure to thank your friend for contributing to the forum. :thumb:
     
  20. May 10, 2019 #40

    Col. Batguano

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    This is really great information guys. Thank you. As an FYI, I bought the gun in a 2017 James D Julia auction. I put on my tweeds, and communicated with Purdey about it. They told me it was originally sold to the Baronet Reverend Sir William Henry Day, of Wellesley castle in 1858. I contacted them to see if they would like to talk about negotiating a deal to return it to the family possession. (I'd be happy to swap it for a new Purdey for instance.) I never heard anything back.

    It's a 40 bore damascus barreled 2 groove pair of barrels that takes belted balls. A mould came with the gun for casting up more of them. 40 bore belted balls are definitely not an "off the shelf item!, I've shot it (benched) 1 time for about 30 -40 shots, and so far haven't found the right powder, patch, lube, ball combination. curiously, the nipples (which appear to be replacements) are sized for a # 10 cap instead of the more common # 11's.

    I have more pictures of it if you guys are interested.
     
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