Not LR but need help

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by 5Redman8, Sep 20, 2004.

  1. 5Redman8

    5Redman8 Well-Known Member

    Messages:
    155
    Joined:
    Nov 18, 2003
    Sorry this is not LR but this is the most knowledgeable place IMO.

    I am shooting a 9.3 x 62 and I am FAR from the load data velocities.

    I do not the the exact data in front but for example the book suggests 56gr of h380 and they get 2400fps. I load it and get 2150fps. I know I am not seating the bullet as deep as they suggest but I want my bullet closer to the lands.

    I am seat about .200" further out than SAAMI. With all loads, i am 200-300fps short of theirs. I ran Quickload and it is running right with my real world data i.e. it says I should be short in fps. It also says I am way under pressure.

    My question is can I bump up my loads and trust Quickload or just deal with being short of fps?

    Also, How much velocity do you lose with you chrony at 15feet. If I am getting 2150fps at the chrony, what am I getting at the muzzle.

    More info I am seating to 3.450" and using Lapua brass with Fed 210m primer Barnes 286gr X bullet.

    Thanks,
    Kyle
     
  2. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

    Messages:
    6,848
    Joined:
    Jun 12, 2004
    5Redman8,

    Oh the joys of handloading,

    First off, if your rifle is built on a strong modern action and your data that lists 2400 fps as a safe top velocity, there are some things you can do to get more velocity.

    It is very common to use published data and when you actually test in your rifle, velocities are well short frm those of the tested data.

    This is for several reasons. THe main reason is that many companies, powder and bullet makers that provide data often use pressure barrels which have min spec, basically match grade chambers and the barrels are often match quality as well with much tighter bore diameters then what we have on many standard grade barrels.

    What this does is produce more velocity and presssure for a give charge of powder then in a looser chamber in a standard barrel. THis is why your velocity is lower and why this is common.

    Seating your bullets out longer also will reduce pressure and velocity unless you are seating into the lands and then pressures can increase.

    Basically what you are doing seating the bullet out farther, especially in a medium bore and big bore rounds is increasing the case capacity of the round which will result in less velocity unless you correct your powder charge for the increased case volume.

    Always keep in mind that velocity is a product of pressure and time. THese are at least the major componants to velocity, sure bore finish and ambiant temps have some influence but by amd large you get a certain velocity from generating a certain amount of pressure behind a bullet for a certain amount of time(the time it take the bullet to travel down teh bore).

    This is relatively constant from one rifle to another as long as the bore is in good condition and the bullets are seated relatively the same to the lands.

    What this means is that if a load data manual lists 2400 fps with a given bullet out of a test barrel, they are generating X amount of energy to accomplish this.

    You will need to generate the same X amount of energy to get the sme results. With the looser chamber and possibly looser bore, and with your seating the bullets out longer, it will take more powder to generate the same amount of pressure in your rifle compared to the test rifle.

    As long as you are alert to the pressure signs and make sure you stay in a safe range, it is perfectly safe to increase your powder charge to reach the velocities listed in the load manuals.

    Keep in mind to check the barrel length the tests data was generated in. If they use a 26" barrel and you have a 22" on your rifle, DO NOT EXPECT TO GET THE SAME VELOCITY because it will take much more pressure to do so in your shorter barrel.

    Also, you may not get the exact velocity without some pressure problems, keep this in mind at all times when increasing your load and velocity.

    Where youare getting 200-300 fps less, you should be able to easily get within 100 fps safely as long as your barrel lengths are real similiar. If you are using a shorter barrel, take 30 fps off for each inch and refigure your target velocity.

    Again, all this only should be used in a modern strong action. If you happen to have a small ring mauser in this caliber which there should not be but I have seen smiths do it, leave your loads where they are.

    If you are using a quality M98 action or any modern commercial action, you should be able to increase your velocity to be very close to published velocities.

    GO slow, increase in 1/2 gr levels in a case with this volume and do not get greedy. Watch for pressure signs and at the first hint of them, back off by enough to make then go away.

    There are also some rifles that will not show pressure signs in the conventional way. My full custom rifles that I build are so tight in the chamber and action specs that you can not read pressure off a case reliably with conventional measurements and get an accurate idea of your pressures.

    Also, soem factory rifles will produce velocities far over listed specs with no pressure signs at all, this does not mean that they are not far over pressured.

    USe velocity as your guide and when you reach listed velocity stop because to get that velocity you have to generate the pressure as well. Even if you have no pressure signs, STOP!

    As far as velocity drop to the chronograph, it varies from 10 to 20 fps in most cases, not really enough to worry about.

    Hope this helps some,

    Good Shooting!!!

    Kirby Allen(50)
     
  3. 5Redman8

    5Redman8 Well-Known Member

    Messages:
    155
    Joined:
    Nov 18, 2003
    It is a CZ550 and the barrels are equivalent.

    You helped a bunch. I have been told to use velocity as a pressure indicator also when working up loads.

    I will do some more work and i may seat the bullets a little deeper as the barnes seem to like a bit of a "jump" anyway.

    Kyle

    [ 09-20-2004: Message edited by: 5Redman8 ]
     
  4. 5Redman8

    5Redman8 Well-Known Member

    Messages:
    155
    Joined:
    Nov 18, 2003
    Would a crimp help....I have never crimped a bullet.

    How would it be done?

    Kyle

    [ 09-20-2004: Message edited by: 5Redman8 ]
     
  5. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

    Messages:
    6,848
    Joined:
    Jun 12, 2004
    5Redman8,

    Keep the Barnes bullet at least 0.030" of the lands or you will get pressure variations. I prefer 0.050" off the lands with the X bullet but thats just me. This is why the X bullet can be tricky to get to shoot really well. One reason I do not care for this bullet.

    Crimping the bullet will certainly increase velocity a bit but often at the expense of accuracy and case life. If you have proper neck tension, there is no real need to crimp a round like the one you are loading for.

    Adjusting your velocity with crimping can be an frustrating and your case length needs to be perfect on all of your brass to get consistant crimps. If they are not you will get velocity variations much wider then had you not crimped at all.

    Again, I do not see a need for crimping any round until you get into the dangerous game loads level of recoil or ammo used in tubular magazines or semi-autos. For these situations, a crimp is needed to keep the bullet in place, this is the only real correct usage of a crimp.

    Good Shooting!!!

    Kirby Allen(50)