WidenersLee PrecisionRotoMetals2Repackbox
Titan ReloadingMidSouth Shooters SupplyInline FabricationADvertise here

Page 2 of 2 FirstFirst 12
Results 21 to 22 of 22

Thread: Normal Case Stretch

  1. #21
    Boolit Master
    Join Date
    Dec 2008
    Posts
    1,708
    That sounds better than my rifle . Do your primers back out at all? My first clue on my rifle was that all of the primers backed out a little bit. As far as I could tell they were backed out by exactly the amount of excess headspace.

    Chris.

  2. #22
    Boolit Bub
    Join Date
    Apr 2009
    Posts
    67
    Quote Originally Posted by Gunlaker View Post
    That sounds better than my rifle . Do your primers back out at all? My first clue on my rifle was that all of the primers backed out a little bit. As far as I could tell they were backed out by exactly the amount of excess headspace.

    Chris.
    No my primers are not backing out.

    I remembered that I had a device with dial indicator that was for determining headspace for contenders and that it would work perfectly for determining how much the case was below the barrel face. I also had a indicator for indicating protrusion that would work for measuring primer back out.

    First as I have posted previously my breach block locks forward touching the barrel face. If you place .001” feeler guage between the block and barrel you can’t get it out. So I removed the breach and hammer to give me room to use the indicator and placed a FL sized case with known rim thickness in the chamber. With the indicator block flat across the barrel face I found the case to be 0.004” below the barrel face. This was using a case with a rim thickness of 0.065”.

    My Starline and Win brass rim thickness varies between 0.065”-0.066”(most at .066”). So this gives me a total headspace of 0.003”-0.004” unless there is some underlying problem with breach lock up that I can’t see. So just to check, I decided to fire an empty case just with a primer and measure the primer back out. The results of that were exactly 0.004”!

    So I’m satisfied that my total headspace is 0.004” which is not excessive. Just to satisfy my curiosity, I loaded a case with 80 grs 1.5f with no compression and just a card wad and fired it. I found no case stretch. I then loaded a 80 gr Load with grease cookie with a little crimp and removed the bullet. Fired this and found no stretch.

    I then annealed 5 cases and loaded 2 with the pp bullet and both stretched 0.008”+.

    It’s pretty clear (to me anyway) that the powder column is ironing out and stretching my brass forward. But why in my chamber when others are not experiencing the same? Is it due to the load not producing enough pressure to blow the case out to the chamber? If so why? Is the bullet not bumping up enough to cause enough resistance for the case to blow out to the chamber? Is my chamber super slick polished?

    Anyway I’ve determined it’s not headspace, and now I’m going to try a 84gr Load without compression. Then a softer alloy and full groove diameter pp and gg. It’s just puzzling to say the least as it appears no one else has experienced this except with excessive headspace or wet chambers.

Page 2 of 2 FirstFirst 12

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check