Welcome guest, is this your first visit? Create Account now to join.
  • Login:

Welcome to the NZ Hunting and Shooting Forums.

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed.

Ammo Direct DPT


User Tag List

+ Reply to Thread
Page 1 of 2 12 LastLast
Results 1 to 15 of 22
Like Tree7Likes

Thread: Random pressure signs?

  1. #1
    Member
    Join Date
    Jun 2013
    Location
    BOP
    Posts
    1,003

    Random pressure signs?

    I'm scratching my head some what....

    Worked up a load for my 308 bushpig last summer with H335 and 150gr nosler BTs. Found an accurate load and loaded up 40 odd rounds. All components the same.

    Have fired 30 odd rounds since without any pressure signs, chronograph them doing 2820fps.

    Went to check zero yesterday after having the stock off and fired 3x of the handloads and had stiff bolt lift and slight ejector marks on all 3 rounds....

    Any idea why this might happen?

    Only things I can think of are:

    - I fired 3 factory rounds 5 min beforehand and maybe the chamber was a bit hot? Was a cool day though. Also load was developed in summer and I went 1gr higher than current load without issue.

    -rounds have been carted about hunting for a fair few trips. Could they have absorbed some moisture? They have been in a pack or the mag most of the time. Not sure if moisture would have this effect?

    Any other ideas?

  2. #2
    GWH
    GWH is offline
    Member
    Join Date
    Jul 2012
    Location
    Napier, Hawkes Bay
    Posts
    4,460
    Carbon ring built up in throat maybe?
    veitnamcam likes this.

  3. #3
    Link
    Join Date
    Jan 2013
    Location
    Canterbury
    Posts
    211
    Where these rounds from the original batch loaded?

  4. #4
    Member
    Join Date
    Jun 2013
    Location
    BOP
    Posts
    1,003
    Quote Originally Posted by GWH View Post
    Carbon ring built up in throat maybe?
    Don't think so. Barrel always kept clean and a dry patch thru the bore before heading out. Had fired 3 factory rounds earlier so wouldn't be any traces of oil left either.

  5. #5
    Member
    Join Date
    Jun 2013
    Location
    BOP
    Posts
    1,003
    Quote Originally Posted by Link View Post
    Where these rounds from the original batch loaded?
    Yup all identical. Same mfg of brass, all preped the same. Same powder,primer and pills.

    No issues with any of the earlier rounds.

  6. #6
    Member Callum's Avatar
    Join Date
    Apr 2013
    Location
    HB
    Posts
    94
    Colder temperatures can create higher pressures, especially when the load is closer to max,
    Last edited by Callum; 17-06-2018 at 09:50 PM.
    338 and Willus like this.

  7. #7
    Lovin Facebook for hunters kiwijames's Avatar
    Join Date
    Feb 2012
    Location
    Hawkes Bay
    Posts
    7,205
    Quote Originally Posted by Callum View Post
    Colder temperatures can create higher pressures, especially when the load is closer to max,
    Explain?
    PERRISCICABA likes this.
    The range of what we think and do is limited by what we fail to notice. And because we fail to notice that we fail to notice, there is little we can do to change; until we notice how failing to notice shapes our thoughts and deeds

  8. #8
    ebf
    ebf is offline
    Mushroom juice ! Hic ! ebf's Avatar
    Join Date
    Jun 2012
    Location
    Above the Hutt
    Posts
    6,872
    carbon ring, or re-check the seating depth

    are you jaming or off the lands ?
    Viva la Howa ! R.I.P. Toby | Black rifles matter... | #illegitimate_ute

  9. #9
    Member Callum's Avatar
    Join Date
    Apr 2013
    Location
    HB
    Posts
    94
    https://www.nzhuntingandshooting.co....ensitive-7447/

    My edge also runs 50fps faster in winter compared to summer, just something I have noticed, might not be the case here with a different powder etc but seems silly not to mention it

  10. #10
    Member
    Join Date
    Apr 2017
    Location
    Christchurch
    Posts
    57
    Did the rounds spend a longer time than normal sitting in your hot chamber?
    ebf likes this.

  11. #11
    Member
    Join Date
    Jun 2013
    Location
    BOP
    Posts
    1,003
    Quote Originally Posted by ebf View Post
    carbon ring, or re-check the seating depth

    are you jaming or off the lands ?
    Off the lands, will recheck seating depth in case they got bumped somehow.

  12. #12
    Member
    Join Date
    Jun 2013
    Location
    Middle Earth
    Posts
    4,301
    I read a thing a while back on some tests done on resized brass:
    Basically the test was on measuring the down ward pressure on the bullet to seat in the neck of the case.
    The pressure on the freshly resized brass was less than some that same batch of brass loaded a few weeks later.
    It soundsg strange but it looked as if the brass hard hardened over time.
    The article was on 6 mmbr.com I will try to dig it out.
    One of them:
    Neck Tension 101 — It Ain’t As Simple as You Think « Daily Bulletin

    Point number 9

    http://bulletin.accurateshooter.com/...e-time-factor/

    This one is the better one

  13. #13
    Member
    Join Date
    Aug 2012
    Location
    helensville nz
    Posts
    4,587
    Im thinking warm ammo ie in the sun in little plastic box for half an hour before shooting?

  14. #14
    Member
    Join Date
    Jun 2013
    Location
    BOP
    Posts
    1,003
    Quote Originally Posted by rambo-6mmrem View Post
    Im thinking warm ammo ie in the sun in little plastic box for half an hour before shooting?
    Nah, straight out the daypack that was under the bench in the shade. Air temp would have been lucky to be in double digits.

  15. #15
    338
    338 is offline
    Member 338's Avatar
    Join Date
    Apr 2012
    Location
    .
    Posts
    364
    I get this all the time in the cold. When I am hunting in the snow some of my loads stamp like a bitch! Keep them in your pocket.
    I have actually tested this a few years ago with 2225 and 2217 powder using ice packs and hand warmers to heat and cool rounds.
    Shot at 400 and had higher velocity’s,higher point of impact and pressure signs on the brass on the cold rounds


    Sent from my iPhone using Tapatalk

 

 

Similar Threads

  1. Signs of pressure in a 6.4x47
    By Puffin in forum Reloading and Ballistics
    Replies: 15
    Last Post: 14-07-2017, 10:14 PM
  2. Signs of something big?
    By Willus in forum Reloading and Ballistics
    Replies: 15
    Last Post: 17-04-2017, 07:12 PM
  3. Over pressure signs ??
    By kiwi39 in forum Reloading and Ballistics
    Replies: 17
    Last Post: 03-01-2014, 10:40 PM
  4. Case pressure signs
    By scoped in forum Reloading and Ballistics
    Replies: 39
    Last Post: 13-02-2013, 11:53 AM

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Welcome to NZ Hunting and Shooting Forums! We see you're new here, or arn't logged in. Create an account, and Login for full access including our FREE BUY and SELL section Register NOW!!