Welcome to M1911.ORG
The M1911 Pistols Organization Forums Site


Happy Fathers Day


Sponsors Panel
If you intend to buy something from the companies advertising above, or near the bottom of our pages, please use their banners in our sites. Whatever you buy from them, using those banners, gives us a small commission, which helps us keep these sites alive. You still pay the normal price, our commission comes from their profit, so you have nothing to lose, while we have something to gain. Your help is appreciated.
If you want to become a sponsor and see your banner in the above panel, click here to contact us.

Page 3 of 3 FirstFirst 123
Results 21 to 24 of 24

Thread: Shrimp of a ‘Crimp’ and the effects ,,,,,

  1. #21
    Join Date
    25th September 2006
    Location
    South of Lake Superior
    Posts
    14,042
    Posts liked by others
    112
    Yes, the folks that run this forum do a good job of keeping things civilized.

    Your 'MRP' brass puzzled me until looking it up here... https://www.cartridgecollectors.org/headstampcodes ...showed it to be made in Brasil for Magtech. The few cases I have from Magtech have a 'CBC' headstamp and are made in the same place as your 'MRP' cases. The thinnest case wall thickness I measured on the three 'CBC' cases was 0.0084" (0.21mm).

    For comparison, the case with the greatest minimum thickness I've ever measured was from Armscor with an AP10 headstamp at 0.0103" (0.26mm) and the thinnest was 0.0071" (0.18mm) on an old R-P Targetmaster case. When measuring for case wall thickness, I probe for the thinnest (and thickest) spot on the assumption the sized case can grip the bullet no better than its thinnest section will allow (sort of the weakest link theory, I guess).

    Q: If you've measured your 'MRP' cases, how thin were they?
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]
    Last edited by niemi24s; 1st June 2021 at 09:14.


  2. #22
    Join Date
    17th June 2019
    Posts
    8
    Posts liked by others
    2
    I don't have any 'CBC' stamped 45ACP brass at hand but in all other calibers they are usually very good, reloadable cases. That's why I was surprised to learn about the origins of the MRP stamped ones.

    As well as I can measure them with my simple vernier calipers the MRP brass are 0.009" (0.23mm) at the mouth.

    S&B are 0.011" (0.28mm), PPU, Federal and PMC too.

    Geco, Starline and Fiocchi/G.F.L. (three more favourites) all 0.012" (0.31mm).

  3. #23
    Join Date
    25th September 2006
    Location
    South of Lake Superior
    Posts
    14,042
    Posts liked by others
    112
    I gave up on vernier calipers years ago for measuring case wall thickness and invested in a good tubing micrometer fitted with a ball attachment on the spindles flat end:
    P(08)3170001b Getting A Grip Post 9.jpg
    It does a much better job of avoiding too-large measurements by getting to the bottom of surface irregularities. Here's a link to few dozen case measurements using it:
    https://docs.google.com/spreadsheets...it?usp=sharing
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]
    Likes (1) :
    mus (3rd June 2021)


  4. #24
    Join Date
    25th September 2006
    Location
    South of Lake Superior
    Posts
    14,042
    Posts liked by others
    112
    This chart contains information like the one in Post #10 plus some additional stuff:
    Case Grip Chart.jpg
    The handload was run only through the Lee CFC dies lower sizing ring and not the upper crimping section. Case OD measurements shown for it were taken at the base of the bullet and at the same diametric position.
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]
    Last edited by niemi24s; 4th June 2021 at 20:15.


Page 3 of 3 FirstFirst 123

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  



Sponsors Panel
If you intend to buy something from Brownells, please use their banners above. Whatever you buy from them, gives us a small commission, which helps us keep these sites alive. You still pay the normal price, our commission comes from their profit, so you have nothing to lose, while we have something to gain. Your help is appreciated.
If you want to become a sponsor and see your banner in the above panel, click here to contact us.

Non-gun-related supporters.
Thank you for visiting our supporters.