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Thread: ideal head space

  1. #1

    ideal head space

    Hi can anyone give me an idea of what is the best head space from the O-give i have a Tikka t3 hunter in 308 and a new Browning a bolt in 243 , i'm using the hornady oal which is very good but although i've backed it off 1000 and 1500 and 2000 of an inch the groupings are much the same i use the same powder primer combination Hodg 140 remmi primers . so any ideas and i'm now very short of H140 so i'm going to change powder probably hogdon but not shure could use vit as well
    K C Rimmington

  2. #2
    Well let's see ............................................... unless you manage to push the shoulders back on your cases you cannot in fact effect the head space. Headspace is the dimension from a point on the shoulder of the chamber to the bolt face. It has nothing to do with bullet seating depth nor bullet jump.

    Somehow I am getting the feeling that your not very competent with handloading and the tools. Your post is what gives me this feeling. For instance 1000 is an inch in thousandths. 1500 = 1 1/2" and 2000 = 2" (2 inches). I can only assume you mean 0.010" (ten thou) 0.015" (15 thou) and 0.020" (20 thou).

    Also as far as I am aware there is no such powder as H140. Even checking Hodgdons site to see if it's new one cannot find one. So am not sure which powder your talking about........................ sorry.

    There is Vhit N140 and you do mention thinking of getting Vhit so I can only assume you have gotten them confused..

    May I also suggest you find someone who is more experienced in hand loading to help you go through it and the use of the tools.

  3. #3
    Kevin

    Firstly, one of many articles on head space.

    http://www.cruffler.com/trivia-October99.html

    Secondly, Brit's points re measurements are important. I recommend that you keep your reloading log up to date with the Imperial measurements that you take as you reload. That way, you will be able to quote them in posts and get good feedback. You will also be able to refer to them when you need them and keep loading ammunition to the same specification.

    Good luck. JCS

  4. #4
    Very good advice from Brithunter & JCS, ultimately once you have mastered loading techniques & measuring headspace correctly there is no ideal distance that someone can tell you, you have to experiment with different loads by trial and error to find this. IMO your first priority should be to determine a bullet weight compatable with the twist rate of your barrel & calibre followed by working up a suitable powder load (stick to the same brand of case & primer whilst doing this). Only then refine this by alterations to headspace. atb Tim

  5. #5
    Heaspace? Altering headspace?? Someone is confused on their terminology, I think.~Muir

  6. #6
    Quote Originally Posted by Muir View Post
    Heaspace? Altering headspace?? Someone is confused on their terminology, I think.~Muir
    Yes, probably but you know what I meant (too much multitasking- I was of course referring to bullet seating depth, thanks for the correction)atb Tim
    Last edited by timbrayford; 05-03-2012 at 16:30. Reason: hurried balls up

  7. #7
    the only way to alter headspace is to change the depth of the bolt lugs or their fit in the bolt lug recess of the action,,or the depth of the bolt face, no?

    nothing to do with reloading IMHO. unless I've lost it.

  8. #8
    kevin what you are referring to is actually the ogive to base length and it sounds like what you are trying to achieve is the best bullet seating depth for your rifle.
    This is very dependant on what bullet you are using and its jacket material.

    Match grade bullets from makers such as Berger are made with a softer jacket material then all other bullets and as such can be safely seated to engrave on the rifling.
    This not the case with Sierra Matchkings and most other game bullets due to their harder jacket material, seating them to engrave the rifling can cause pressures to rise sharply.
    Hence game bullets are best seated away from the rifling lands, this can be anyhting from a few thousandths of an inch away up and even more then an eighth away.

    This seating depth can only be found out by trial and error, what works in one rifle may not work in another but a good starting point is ten thousandths away (.010") and through experimentation work either way untill you find a seating depth that groups best.
    However before you fine tune your bullet seating depth make sure you have the best powder charge for your chosen bullet.

    Ian.

  9. #9
    "Match grade bullets from makers such as Berger are made with a softer jacket material then all other bullets and as such can be safely seated to engrave on the rifling.
    This not the case with Sierra Matchkings and most other game bullets due to their harder jacket material, seating them to engrave the rifling can cause pressures to rise sharply."

    I did not know that, learn something new every day

  10. #10
    Well I was typing a response when the power went out yet again. Hopefully it's back for a while this time.

    Yes, probably but you know what I meant
    It's exactly reasons like this that is why I keep on about people using the right terms. It's no wonder new comers to our sport and past time of Handloading get so confused when those that have been doing it for longer cannot be bothered to learn and use the correct terms .

    twas :-

    Bullet Jump

    that the O/P was asking about. I am sorry to say that it's far from uncommon for poor advice on hand loading to be given on the forums.

    Now if one is going to get into loading exotic mono metal bullets then surely one should do some research into them and what is suitable and what may not be. The manufacturers sites would be the first place to start. The reason of course is that most mono metal (bullets of one metal type construction) are lighter than lead cored bullets so a 165 grain Mono metal bullet will be quite a bit longer than a typical lead cored bullet
    and being longer will require a faster rifling twist.

    As for bullet jump ans seating depth I normally start with the base of the bullet when seated level with the juncture of case neck and shoulder is at all possible and shoot for group then seat the bullet out a bit more and re-test until we get t
    he precision on target I am looking for. Sometimes it does not work out so a change in primer or powder is called for and try it all again. Other times the initial load works so well no or only minor tweaking is needed.

    I have never bothered with a
    comparator or lock'n' load as most production soft point bullets vary in normal production to make it possible to really say that each bullet is the same. Likewise unless the bullet gauge used matches the exact diameter of the bore of your rifle your only fooling yourself and really in fact have no idea what the exact bullet jump in your rifle is.

    I have to smile when I see claims of bullets seated 0.002", 0.005" or 0.010" off the lands as the chances are that in each box of normal SP bullets that there are bullets in there from more than one forming die and the variation cane be as much as 0.025".

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