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Thread: Bullet Comparator 2

  1. #1

    Bullet Comparator 2

    Following on from the advice a couple of weeks a go, I have purchased the hornady comparator and oal gauge. Having used the gear I have produced a few rounds with a OAL length difference of oo6 thou. Just to put my mind at rest, for you guys who are experienced reloaders is this ok, if not how would I go about reducing the discrepency.

    In addition to the above the rounds I made up originally without the oal gauge are chambering onto the lands tight, is this dangerous and should I discard the previous rounds??
    Thanks in advance.

  2. #2
    A bullet set nearer to the lands will produce higher pressures than one further away, so touching the lands is more risky than one not touching the lands.
    It does depend on the pressures developed and the pressures the barrel and action is designed to withstand.

    The Hornady comparator does not measure from the bolt face so there are inherrent inaccuracies in using one.

    I use a half sizes case so the bullet is a friction sliding fit and I insert the case and bullet into the chamber and lock down then extract and measure the OAL, doing this 5 times to get an average.

    When I do load development I load 5 round batches at 0.030, 0.060, 0.090 and 0.120 inches off the lands then fired them to find the ones with the best accuracy.

  3. #3
    maxwell

    6 thou variation in OAL sounds ok to me. My stalking round varies +-2 thou. Many factors come in to play, two significant ones are bullet dimensional consistency and neck tension. I don't measure individual bullets, however I do work at my brass prep to achieve consistent neck tension.

    If you worked up your previous rounds and you are happy that they aren't showing signs of excessive pressure, then use them up. If you are unsure, run them through your seating die again and seat them further into the cases. Again beware that if you seat them too far in, pressure will again increase, but seating them 10-20 thou off the lands shouldn't cause any problems. I have one current load of 107gr SMKs that seats 5 thou into the lands. Some are on the lands and others are off the lands. 68gr Bergers are 148 thou off in the .243.

    Finally, although a forum like this is helpful (most of the time), read the Lee reloading book and find someone local that you can turn to for advice too.

    Good luck. JCS
    Last edited by jcampbellsmith; 28-10-2010 at 21:07. Reason: more info

  4. #4
    Guys,

    The only time I ever had a negligent discharge (or whatever the case may be) was with an Estate Rifle with reloads. I had no problem on the two check shots I took before going on the stalk.

    When we got dropped of for the stalk I "put one up" as requested. I closed the bolt and found it tight. As I applied more pressure to complete the closure my knuckle came into contact with the trigger just after closure. The rest is history. Safe history....

    What I now do with all ammunition in my own rifle (I use a Mauser M03 so a manual cocker) is run ALL factory rounds through to ensure a smooth cycle. I have started to reload and do the same.


    Stan

  5. #5
    Thanks for the replies. I've reseated the rounds of the lands at various sizes to try and find the 'sweet spot'.

    One thing I have noticed is that the crimping die is making the rounds 'grow' and so end up putting them through the seating die for a second time after crimping to get the correct size!!

  6. #6
    maxwell

    One point to add to my earlier comment, I don't crimp or soft seat. I use bushing dies to achieve a firm grip on the bullet. Secondly, I am not sure that reseating crimped bullets is a good idea, but I look to experienced 'crimpers' to give a definitive comment on this.

    Regards JCS
    Last edited by jcampbellsmith; 30-10-2010 at 19:05.

  7. #7
    Quote Originally Posted by jcampbellsmith View Post
    maxwell

    One point to add to my earlier comment, I don't crimp or soft seat. I use bushing dies to achieve a firm grip on the bullet. Secondly, I am not sure that reseating crimped bullets is a good idea, but I look to experienced 'crimpers' to give a definitive comment on this.

    Regards JCS
    I'll agree with that. Once crimped, they are to be shot.
    As to the comparator... This kind of discussion is the reason one should stay away from them! I have a friend who had a really accurate load for his 30-06 but, after buying a comparator, has now gone freak over the difference in OAL. Now the load seems faulty and he wants to scrap his reloading gear and buy semi-custom stuff to eliminate the .005" variance he never knew existed when he was bragging on his rifle's accuracy.

    As to loading to the lands. It doesn't necessarily increase pressures. If you have set yourself on an reasonable load with the bullet seated to, say, the base of the neck, and then seat it progressively outward to the lands, the pressures should theoretically drop as you are increasing case capacity while keeping the powder charge the same.~Muir

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