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Thread: Seating depth help

  1. #1

    Seating depth help

    When I am seating the bullets during the reloading process, I will get at least one out of a batch of 20 that seats deeper than the rest and for no apparent reason. I have checked and cleaned the seating die but still this happens, any ideas what is causing this?Also currently I remove the bullet and start again resizing, could I reduce the seating depth using my kinetic hammer to the correct depth and if I do this:
    a) will this be safe
    b) would this impact upon accuracy
    c) would this effect velocity
    I am using .243 sierra gameking 100gr spritzer boat tails.


    All advice welcomed.​
    ATB 243 Stalker
    Last edited by 243 Stalker; 15-09-2013 at 13:49.

  2. #2
    How much of a difference are you talking about and how are you measuring it?.

    Are you full length or neck sizing your brass and trimming to length?.

    If your anywhere near the Durham/Sacriston area I'd be happy to take a look for you.
    There's room for all Gods creatures ........... right next to the mash and gravy

  3. #3
    You're lucky. If I seat a batch of fifty, I might have a couple seat long and 8-10 seat short. There's less neck tension in the necks that seat long. Well spotted and welcome to the frustrations of reloading.

    I mark and set aside the rounds that seat long or short. If you test them at 100yds, I bet you won't notice any difference to the rest of the rounds. Rounds I'm not happy with, I keep as foulers, it's not worth the bother of doing any rework on them.

    Have fun.

    JCS

  4. #4
    If you seat the same bullet (cross sectional profile) using the same seating die and fully seat every round they should all measure the same OAL within a few thou" at most.

    If your seating die puts a lot of pressure on the bullet tip while seating and you're using soft points there may be a larger difference as a slight deformation of the point is more possible than with a full metal jacket type bullet.
    Last edited by phaedra; 15-09-2013 at 14:34.
    There's room for all Gods creatures ........... right next to the mash and gravy

  5. #5
    Phaedra - normal OAL is 2.630, the ones that are seating deeper are 2.624 and I am using a micrometer to measure.
    I am full length sizing and case trim to 2.035
    You make a good point regarding soft points, I might measure the bullets before seating to see if this is the cause.
    ​ATB 243 Stalker

  6. #6
    A possible cause of this problem could be if you don't trim or trim before sizing & don't trim all cases to exactly the same length - this can lead to different case lengths & if you then use the seating die to crimp as well you could be deforming the case at the shoulder. Then the varying elasticity of cases leads to different permanent deformation hence varying C.O.A.L.
    Better to not crimp using a seating die, use a collet type crimper (Lee Factory Crimp) AND always trim to the same length and chamfer the case mouths evenly for each batch of reloads.
    ​Consistency is the key & of course always measure to the ogive - not to bullet tip.

    Ian

  7. #7
    Hi, the first thing I would question is how are you measuring your COL? If you are measuring from the case head to the bullet tip I would expect your variations in length, however if you are using a comparator body with the correct calibre insert then your measurements really shouldn't be any more than perhaps 2 thou apart. This has nothing to do with neck tension as mentioned above as long as you achieve a full stroke with the press and as the seating die will apply pressure to the bullet ogive to seat the bullet so should not affect the bullet head dimensions (unless the neck tension is ridiculous). bullet heads can vary quite a lot if measured from base to tip (especially soft points and hollow points unless the latter are trimmed with a Meplat trimmer) however if measured from the base to the ogive with the relevant comparator they will be far more consistant and this is how all measurements should be taken. Too be honest it sounds as though you are not using a comparator and if that's the case a 6 thou difference is nothing and I would expect them to be far more consistant if you measure them again using the correct calibre insert in a comparator.
    Last edited by RPA 6MM BR; 15-09-2013 at 15:01.

  8. #8
    Quote Originally Posted by 243 Stalker View Post
    normal OAL is 2.630, the ones that are seating deeper are 2.624r
    If you're only talking about 6 thousands of an inch difference in OAL (measured tip to end of case) it's not going to affect anything (unless you load with your bullets touching the lands). 2.63" is well within Saami spec for a .243 (2.54 - 2.71) so I wouldn't worry about it
    There's room for all Gods creatures ........... right next to the mash and gravy

  9. #9
    The difference in your seating depth could be down to neck tension i.e the tension the bullet is being held by the case when you are pushing the bullet into the case , or it could be a slight deformity to the end of bullet.
    So if you were to load say five rounds to your preferred OAL ,measure case base to bullet point, then measure these rounds from case base to bullet shoulder or ogive and use this measurement to check your length you may well find you are more consistent than you think , this way you are avoiding any bullet point deformity .
    Target or longrange vermin control is were these small discrepancies will haunt you .

    Cheers

  10. #10
    Quote Originally Posted by 243 Stalker View Post
    Phaedra - normal OAL is 2.630, the ones that are seating deeper are 2.624 and I am using a micrometer to measure.
    I am full length sizing and case trim to 2.035
    You make a good point regarding soft points, I might measure the bullets before seating to see if this is the cause.
    ​ATB 243 Stalker

    More than likely that is the cause I as have found out when I buy bullets I measure and split them just so I know it's 100%

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