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.

Night Vision NZ Alpine


User Tag List

+ Reply to Thread
Page 1 of 5 12345 LastLast
Results 1 to 15 of 71
Like Tree98Likes

Thread: Rounds jamming into lands

  1. #1
    Member
    Join Date
    Jan 2018
    Location
    Otorohanga
    Posts
    111

    Rounds jamming into lands

    Evening guys, ran into a problem this afternoon with a few rounds jamming into the rifling. I rechecked the coal and ojive measurements and they match near perfect with the rounds that are chambering fine.
    I've done a jam measurement in the past and they're seated 25 thou off jam. Brass was all necksized then sorted to right length.
    I fired a couple and the bolt was stiff to lift, is this indicaticating a problem in the neck or shoulder?

    I'm new to reloading so won't be surprised if I'm missing something pretty obvious, any help or thoughts would be great.
    Cheers

  2. #2
    Member
    Join Date
    Dec 2018
    Location
    Christchurch
    Posts
    451
    In addition to the above... neck tension may not be enough also.

    Sent from my SM-G975F using Tapatalk
    Ubique.
    Once divided, always conquered.

  3. #3
    Almost literate. veitnamcam's Avatar
    Join Date
    Dec 2011
    Location
    Nelson
    Posts
    24,972
    What is your indicaction they were jamming into lands? did you stick a round in the chamber and try to eject a live round and have the bullet stick in the barrel?
    Your lands dont move back and forward so something in your measurements is asmiss.

    Need more information.
    tetawa, Moa Hunter and mimms2 like this.
    "Hunting and fishing" fucking over licenced firearms owners since ages ago.

    308Win One chambering to rule them all.

  4. #4
    Member Micky Duck's Avatar
    Join Date
    Apr 2015
    Location
    Geraldine
    Posts
    24,797
    are you 100% positive its projectile jamming into rifling???? eg did you open bolt and find marks on projectile or COULD it be the sizing die loosened slightly and case is tighter than normal somewhere else,eg shoulder is rubbing.....
    Ive been caught by it before is why I mention it.

  5. #5
    Almost literate. veitnamcam's Avatar
    Join Date
    Dec 2011
    Location
    Nelson
    Posts
    24,972
    Have re read your post.
    Are you reading stiff to close the bolt as jamming in the lands? If so this may actually just be that the cases you have neck sized are due a shoulder bump.this will also explain slight stiff opening of bolt.
    Moa Hunter and keneff like this.
    "Hunting and fishing" fucking over licenced firearms owners since ages ago.

    308Win One chambering to rule them all.

  6. #6
    Gone but not forgotten
    Join Date
    Apr 2017
    Location
    Hamilton
    Posts
    4,129
    Heavy bolt lift is probably due to those rounds being over-pressure, due to the projectile being jammed (so higher pressures being generated before the projectile will move).

    But my first question is...How do you know the rounds are jamming into the rifling?

  7. #7
    Member
    Join Date
    Jan 2018
    Location
    Otorohanga
    Posts
    111
    Na no signs of pressure and were 2grns lower than max load in hornady manual. rounds were tight to chamber and leaving rifling marks on the projectiles.
    Rifle is a fierce 24inch 7mmRM, rounds are 162 eldx and 66.5grn upto 68grn h-1000,3rd reloading aswell as annealed and sorted to right length.
    Unsure on velocity, concentricity and havnt been neck turned.
    mimms2 likes this.

  8. #8
    Member
    Join Date
    Jan 2018
    Location
    Otorohanga
    Posts
    111
    Ok jammed causing the high pressure males sense to me

  9. #9
    Member 40mm's Avatar
    Join Date
    May 2017
    Location
    North Auckland
    Posts
    5,921
    It is plainly obvious. He is not shooting a .308
    Moa Hunter likes this.
    Use enough gun

  10. #10
    Member
    Join Date
    Jan 2018
    Location
    Otorohanga
    Posts
    111
    Name:  20210914_200627.jpg
Views: 657
Size:  2.74 MB

  11. #11
    Member
    Join Date
    Jan 2018
    Location
    Otorohanga
    Posts
    111
    Quote Originally Posted by veitnamcam View Post
    Have re read your post.
    Are you reading stiff to close the bolt as jamming in the lands? If so this may actually just be that the cases you have neck sized are due a shoulder bump.this will also explain slight stiff opening of bolt.

    Yea I was thinking along these lines of shoulder bump issue. Is the only way to really figure this out with a headspace gauge for the comparator?

  12. #12
    Almost literate. veitnamcam's Avatar
    Join Date
    Dec 2011
    Location
    Nelson
    Posts
    24,972
    Quote Originally Posted by kayneb View Post
    I dunno what that is but it is not a mark from your lands.
    Looks like a dent?
    "Hunting and fishing" fucking over licenced firearms owners since ages ago.

    308Win One chambering to rule them all.

  13. #13
    Member Micky Duck's Avatar
    Join Date
    Apr 2015
    Location
    Geraldine
    Posts
    24,797
    nah...felt tip pen a tight round..chamber it a few times and see where its touching..

  14. #14
    Member
    Join Date
    Jan 2018
    Location
    Otorohanga
    Posts
    111
    Quote Originally Posted by ripped undies View Post
    just one mark or are they equally spaced around projectile
    Just the 1 deep gauge like in pic but there is a bit of scuffing and tiny dents around the projectile

  15. #15
    Almost literate. veitnamcam's Avatar
    Join Date
    Dec 2011
    Location
    Nelson
    Posts
    24,972
    Take a fired case that chambers easily and one of the ones that was stiff to open and measure them both on the shoulder....you could use say the 45 cal comparitor or whatever just use the same on each.
    Set up fl die to just bump back to the lenght of the fired case that chambers easily to up to minus 2 or 3 thou less max.
    mikee and Moa Hunter like this.
    "Hunting and fishing" fucking over licenced firearms owners since ages ago.

    308Win One chambering to rule them all.

 

 

Similar Threads

  1. Bird lands on rabbit
    By video hunter in forum Varminting and Small Game Hunting
    Replies: 5
    Last Post: 27-11-2020, 12:58 AM
  2. Tikka t3x 6.5 x 55 maximum oal just touching the lands?
    By Sr5dan in forum Reloading and Ballistics
    Replies: 9
    Last Post: 26-10-2018, 08:47 AM
  3. need some help with new mossberg 590a1 jamming
    By greatday in forum Firearms, Optics and Accessories
    Replies: 2
    Last Post: 08-07-2014, 11:53 PM
  4. .223 Rounds
    By James J. in forum Firearms, Optics and Accessories
    Replies: 52
    Last Post: 20-03-2014, 07:49 PM

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!!