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Seems counterintuitive to me... reloaders?

GunNutGunNut Posts: 7,642 Senior Member
edited December 2019 in General Firearms #1
Hogdon gives the same loads for rifle and handguns in the same chambering.  The below seems wrong to me when using slow burning powders like H110 in a carbine vs let’s say a Ruger with a 4.6” barrel.  I would think a longer barrel would allow a build of a longer pressure spike before barfing out a bunch of unburnt powder no?  Can someone smarter than me explain this?

From the Hogdon manual:

The first thing to remember is that the chamber dimension does not change based upon application. A 223 Remington chamber is the same whether the gun it is in is a handgun or a rifle. The chamber dimension determines the pressure. So, the pressure is the same when fired in that chamber in a rifle or a handgun. The barrel length has no impact on the chamber pressure and hence the reloading data (powder charge and pressure).

Replies

  • mitdr774mitdr774 Member Posts: 1,770 Senior Member
    edited December 2019 #2
    Looking through the Hornady manual for a couple options in both rifle and handgun, they do list different max charges.  This may just be due to differences in chamber or type of firearm used though.  I do know that some of my .44 mag rifle loads are not usable in my 629 and some of my 629 loads are not usable in my rifles.  Even the rifles have different max loads.

    In a perfect world, I dont think barrel length would be an issue.   As the bullet travels down the barrel the area the burning propellant has to expand into keeps getting larger.  In QL the main pressure spike seems to happen in the first 1-2" of bullet travel,assuming the calculations for the graph are accurate.
  • earlyagainearlyagain Posts: 7,928 Senior Member
    edited December 2019 #3
    Smokeless powder makes pressure progressively during the burn. The amount of time a bullet is in the barrel, refered to as dwell time, measured in miliseconds, contains the pressure, allowing progressive increase.

    The above is of course a simplistic discription that negates other potential variables.

    Pressures also reach their peak at different times during ignition. Also measured in miliseconds. This is measured and calculated into published lab tested data with the use of electronic transducer pressure instruments.

    This is why Weatherby rifles and 5.56 chambers are throated differently than standard or 223 chambers. Anything that contains the pressure longer or at a different point during the ignition event. Again measured in miliseconds. Changes or increases the amount of pressure produced for a given load recipie.
  • GunNutGunNut Posts: 7,642 Senior Member
    Wow fascinating stuff!
  • SpkSpk Senior Member Posts: 4,739 Senior Member
    It's essentially what knite said. The pressure will reach it's peak within the first 1-2 inches depending on burn rates. Powder turns to gas, Volume increases, Temperature goes up, Pressure goes up but the bullet starts moving down the barrel increasing the volume allowing for more propellent to turn to gas and the process repeats until the usable propellent is spent (happens in milliseconds, inches from the chamber). Even after the powder is burnt you still have all this high pressure gas trying to get out. That's the hot gas that continues to act on the bullet pushing it forward. Longer barrel, more time to push it forward. More velocity.
    Check out this chart for example:
    The pressure may be dropping from Peak to something less than peak but that's still a lot of high pressure gas pushing the bullet forward! Longer barrel begins to make sense now right. What about the flames/fireball? Some of the unburnt particles that fly out the muzzle mix with the surrounding air and ignite and some of it is weakly ionized plasma (light show). Don't worry you're not wasting half your powder out the muzzle (it's not black powder 😁)
    Here's a nice article on pressure, velocity and distance.

    Enjoy



    Never argue with stupid people, they will drag you down to their level and then beat you with experience -- Mark Twain
    How easy it is to make people believe a lie, and [how] hard it is to undo that work again! -- Mark Twain

  • zorbazorba Senior Member Posts: 24,985 Senior Member
    AND - I learned something new today!
    -Zorba, "The Veiled Male"

    "If you get it and didn't work for it, someone else worked for it and didn't get it..."
    )O(
  • SpkSpk Senior Member Posts: 4,739 Senior Member
    If you really want to confuse yourself or understand better (it could go either way 😁) look up the General Gas Equation/Ideal Gas Law.
    Specifically, PV=nRT where P is Pressure, V is volume and T is Temperature. Don't worry about n( # of moles of gas) or R(ideal gas constant) and just look how P=T/V are related. You'll see that as Temp goes up, Pressure goes up as long as you hold the Volume constant. Once you allow Volume to increase (bullet moving down the barrel) then the Pressure and Temperature begin to decrease (gun boom avoided!)
    You're right, it's all fascinating stuff.
    Never argue with stupid people, they will drag you down to their level and then beat you with experience -- Mark Twain
    How easy it is to make people believe a lie, and [how] hard it is to undo that work again! -- Mark Twain

  • LinefinderLinefinder Moderator Posts: 7,749 Senior Member
    Knitepoet and SPK saved me a lot of typing. Thanks, guys.

    If you handload, QuickLoad will be the best $150 you'll ever spend. Given a choice between QuickLoad or $1K worth of components of my choice I'd pick QL in a heartbeat. It a great product.
    Mike

    "Walking away seems to be a lost art form."
    N454casull
  • GunNutGunNut Posts: 7,642 Senior Member
    I just got an education today.  The big surprise is how quickly max pressure is reached.  That kind of explains every thing else.
  • BigslugBigslug Senior Member Posts: 9,327 Senior Member
    Maybe this will help illustrate the increasing bore volume issue Spk is talking about:

    Chamber pressure of 5.56 NATO is something on the order of 55,000 to 60,000 PSI

    As the bullet travels down the barrel, the remaining pressure at the gas port of an M4 carbine is under half that.  Move the port out to the length of an M16 rifle, and you're down to 10,000-15,000.

    Peak pressure is reached FAST.  In the chamber, you have to first overcome the friction with the cartridge case, then you have to swage the bullet into the rifling.  Due to the vagaries of the powder burn, you may make peak pressure while that's still going on, but if you don't it will be VERY shortly after, because bullet friction goes WAY down after it gets squeezed and volume of bore for that gas to expand in goes WAY up as the bullet travels.

    What the longer barrel does is give more time for that expanding gas to push on the bullet.
    WWJMBD?

    "Nothing is safe from stupid." - Zee
  • snake284snake284 Senior Member Posts: 22,429 Senior Member
    edited December 2019 #11
    GunNut said:
    Hogdon gives the same loads for rifle and handguns in the same chambering.  The below seems wrong to me when using slow burning powders like H110 in a carbine vs let’s say a Ruger with a 4.6” barrel.  I would think a longer barrel would allow a build of a longer pressure spike before barfing out a bunch of unburnt powder no?  Can someone smarter than me explain this?

    From the Hogdon manual:

    The first thing to remember is that the chamber dimension does not change based upon application. A 223 Remington chamber is the same whether the gun it is in is a handgun or a rifle. The chamber dimension determines the pressure. So, the pressure is the same when fired in that chamber in a rifle or a handgun. The barrel length has no impact on the chamber pressure and hence the reloading data (powder charge and pressure).
    Depends on the burn rate of your powder. I no longer reload hand guns. But all my rifles I load for. I use fast powders for my Garands and my one lever gun, an 1894 Winchester AE in .30-30 Winchester. I use a lot of 4831, both Hodgdon and IMR. Both great propellants. They both work great in my .30-06 Springfield and .270 winchester. I also love Reloader powders too. I use RL-17 in my .250 Savage, my .257 AI and my .243 Win. I really love RL-22 in my 7 Rem. Mag. and RL-25 in my .300 WBY. Mag. Lots of great powders out there nowadays that can put your garden variety .30-06 or .243 in a different class.

    Barrel length has no impact but throat length can.  At least in a rifle. A longer throat can let you increase powder charge by as much as 2-3 grains, depending on bore diameter and cartridge. Look at the 6.5 CM vs. the .260 Rem. in a true short action such as a Remington 700. The CM can best the Remington a couple hundred FPS because the shorter cartridge permits seating bullets farther out. If you have a long throat you can seat bullets out where you can make significant gains in the shorter CM. Now in an intermediate or long action you can seat both out to whatever your throat permits and if you have a long throated 6.5 Remington it is clearly superior to the CM., due to larger case capacity.
    Daddy, what's an enabler?
    Son that's somebody with nothing to do with his time but keep me in trouble with mom.
  • snake284snake284 Senior Member Posts: 22,429 Senior Member
    snake284 said:
    GunNut said:
    Hogdon gives the same loads for rifle and handguns in the same chambering.  The below seems wrong to me when using slow burning powders like H110 in a carbine vs let’s say a Ruger with a 4.6” barrel.  I would think a longer barrel would allow a build of a longer pressure spike before barfing out a bunch of unburnt powder no?  Can someone smarter than me explain this?

    From the Hogdon manual:

    The first thing to remember is that the chamber dimension does not change based upon application. A 223 Remington chamber is the same whether the gun it is in is a handgun or a rifle. The chamber dimension determines the pressure. So, the pressure is the same when fired in that chamber in a rifle or a handgun. The barrel length has no impact on the chamber pressure and hence the reloading data (powder charge and pressure).
    Depends on the burn rate of your powder. I no longer reload hand guns. But all my rifles I load for. I use fast powders for my Garands and my one lever gun, an 1894 Winchester AE in .30-30 Winchester. I use a lot of 4831, both Hodgdon and IMR. Both great propellants. They both work great in my .30-06 Springfield and .270 winchester. I also love Reloader powders too. I use RL-17 in my .250 Savage, my .257 AI and my .243 Win. I really love RL-22 in my 7 Rem. Mag. and RL-25 in my .300 WBY. Mag. Lots of great powders out there nowadays that can put your garden variety .30-06 or .243 in a different class.

    Barrel length has no impact but throat length can.  At least in a rifle. A longer throat can let you increase powder charge by as much as 2-3 grains, depending on bore diameter and cartridge. Look at the 6.5 CM vs. the .260 Rem. in a true short action such as a Remington 700. The CM can best the Remington a couple hundred FPS because the shorter cartridge permits seating bullets farther out. If you have a long throat you can seat bullets out where you can make significant gains in the shorter CM. Now in an intermediate or long action you can seat both 6out to whatever your throat permits and if you have a long throa0.ted .260 Remington it is clearly superior to the CM due to the greater case capacity of the .260.

    Daddy, what's an enabler?
    Son that's somebody with nothing to do with his time but keep me in trouble with mom.
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