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Thread: Muzzle energy

  1. #1

    Muzzle energy

    I am a novice reloader, and following the recent thread about the use of a chronograph (an instrument I do not have) I have been trying to determine the velocity required from my loads to obtain a deer legal muzzle energy of 1700 ft.lb.
    It seems from the tables I have, and using a calculator I found on the web, that such a velocity can only be provided by loads in the mid to upper reaches of the range.
    My question is therefore, what is the point of starting from the lowest end of the scale, as normally recommended, when working up a load if it doesn't produce a legal muzzle energy? Would it not be more practical to start somewhere in the middle ?
    I would be grateful for any advice.

    Richard

  2. #2
    It's a safety thing mate. Your rifle will have different internal dimensions to the test rifle used in producing the load info for the book. The 243 (I assume you are talking about this calibre) is marginal for power as you have already mentioned. The writers of the load data don't care about UK deer legislation.

    I used a 243 for a few years. I found the best medicine for deer with a 243 was a Sierra 100gn GameKing, trotting along at around 3000fps.

    Everything I pointed it at died...some more quickly than others.

    ATB

  3. #3
    Quote Originally Posted by Richard S View Post
    I am a novice reloader, and following the recent thread about the use of a chronograph (an instrument I do not have) I have been trying to determine the velocity required from my loads to obtain a deer legal muzzle energy of 1700 ft.lb.
    It seems from the tables I have, and using a calculator I found on the web, that such a velocity can only be provided by loads in the mid to upper reaches of the range.
    My question is therefore, what is the point of starting from the lowest end of the scale, as normally recommended, when working up a load if it doesn't produce a legal muzzle energy? Would it not be more practical to start somewhere in the middle ?
    I would be grateful for any advice.

    Richard
    It is all about working the load up and looking for pressure signs on the case. A safety procedure.
    The only way to tell if your ammunition is compliant is with a chrono.

    Enter the squeals of anguish from 'the deer can't tell' 'no ones ever been checked' etc etc. Simply put you need with 100gn bullet >2770fps to comply in England.

  4. #4
    Thanks for the replies,

    Yes, it is for 243. It does seem that I am looking to achieve around 3000fps for a 95 grain bullet and a little over for an 87 grain. To reach this I expect I will need somewhere around 42 grains and 40 grains respectively of N160.
    I have been loading 38.1 grains which group well, but I now realise are falling way below required muzzle energy. I know from another thread that others are using around 44 grains for similar bullets, so I am now proposing to start working up from 40 grains for the 95s. I don't want to appear to be a cheapskate or to be cutting safety corners, but also I don't want to make up and fire dozens of rounds which I know will not achieve the required energy.

    Does everyone else worry about checking the 1700ftlb ? I realise as JB has said that it can only be checked accurately with a chrono, but for me , and I'm sure many others, this is not an option.

    Am I making too much of this ?

    Richard

  5. #5
    Quote Originally Posted by Richard S View Post
    Thanks for the replies,

    Yes, it is for 243. It does seem that I am looking to achieve around 3000fps for a 95 grain bullet and a little over for an 87 grain. To reach this I expect I will need somewhere around 42 grains and 40 grains respectively of N160.
    I have been loading 38.1 grains which group well, but I now realise are falling way below required muzzle energy. I know from another thread that others are using around 44 grains for similar bullets, so I am now proposing to start working up from 40 grains for the 95s. I don't want to appear to be a cheapskate or to be cutting safety corners, but also I don't want to make up and fire dozens of rounds which I know will not achieve the required energy.

    Does everyone else worry about checking the 1700ftlb ? I realise as JB has said that it can only be checked accurately with a chrono, but for me , and I'm sure many others, this is not an option.

    Am I making too much of this ?

    Richard
    It is up to you what corners you want to cut and I'm not advising that you do, generally the advise is 'work up carefully' use the opportunity to get some trigger time too. You might want to stick with factory stuff if you are not feeling comfortable reloading.
    Most do not bother with checking their velocities, I do, of course this will change with the first test done by forensics laboratories......

  6. #6
    Thanks Joe,

    It's not that I'm not comfortable with reloading, and obviously more experience is necessary. I'm just interested in the performance of my loads apart from grouping, as that seems to be the usual criterion for a successful load.

    Richard

  7. #7
    It's your decision mate. There is no grey area, you either comply or you don't.

    As for where you start load development, that is also up to you. I no longer use a load manual for anything other than seeing where they peaked out at the top end and even that is only a guide since I load considerably longer than the book COAL. I noticed that when I started out that generally speaking the best load to be had was in the upper half of the suggested load range. However you must understand that your rifle may experience considerably higher pressure with a lot less powder than the test barrel used for the book.

    It's your face and your eyes sat behind the chamber when the overpressure occurs, so once again it's your choice on whether the risk is worth saving a few against losing eyes, fingers or life.

    You don't need to make up dozens of rounds. I start at the beginning fire a single round over the chronograph and move up in .5gn increments for the 270 and .3gn for the 223 and see where I sit with regard to the advertised velocity. Remembering there is no such thing as cold fusion, I want to be in the ballpark. If I see a high velocity then I'm probably getting that with higher pressure. I then proceed accordingly.

    When I have a good baseline for the rifle I then switch to the OCW method and go from there.

    ATB

  8. #8
    for me this is simple

    you know what charge you need for a specific velocity (even the VV data will give you a rough idea, and you have seen what others are using)

    Any loads below that are of no value to you and the only reason you are loading them is to prove they do not show pressure in your rifle.

    I load ONE round of any charge between minimum and the level at which I have decided I want to start load testing, purely to check for pressure signs.

    If I where you I would be doing
    38grx1, 38.5grx1, 39grx1, 39.5grx1, 40grx3, 40.5grx3, and maybe 41grx3, beyond that you are on your own,
    you can use smaller increments if you wish but you are trying to reach a charge level safely.
    if you then wanted to tweak 40.2, 40.4 40.6, 40.8 etc that is up to the accuracy they show and how anal you want to take it

    I personally would take it further to ascertain the max for my rifle
    but I am not going to suggest you do this without someone with more experience with you to check the cases and reactions

    Lets not be melodramatic about it
    Overpressure happens a lot!! people don't tend to lose eyes and fingers from putting 0.5 or even 1gr of (the right) powder too much
    Rifles are built and proofed at much much higher levels than the normal reloader will ever see. (the proof house go out of their way to use much more in the way of overloads with heavier bullets)
    you might get a stiff bolt, a flattened primer, a extractor mark on the case head.

    Without looking at quickload or any other app I am pretty confident with a standard barrel a 40gr charge will get you over the required MV
    sure someone else can confirm this

    VV max data for 90gr is 44gr N160 and around 3100fps
    max data for 100gr is 38gr N160 and 2964fps

    2840fps with 95gr gets you over the required ME
    Last edited by bewsher500; 04-11-2013 at 09:42.

  9. #9
    Quote Originally Posted by j0e_bl0ggs View Post
    Simply put you need with 100gn bullet >2770fps to comply in England.
    or a 6.5 x 55!
    tin hat on

  10. #10
    The problem Richard is that the .243w round only just meets minimum legal requirements for larger deer using most factory ammo in a rifle with a reasonable length barrel. Reloading data is sometimes hyped up slightly and anyway it is shot in a test barrel normally.
    Until you run your loads over a chronograph you will never now for certain what velocities and muzzle energies you are actually achieving, at best you will only have a rough guess. If you are genuinely concerned and you don't have access to a chronograph drop me a pm and we will see if we can sort out a trip over to Monmouth where for a small range fee you will be able to run your loads over the chronograph on the indoor range.
    It's the calibre of the shooter that counts not the calibre of the rifle.

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