Page 16 of 21 FirstFirst ... 61415161718 ... LastLast
Results 151 to 160 of 203

Thread: HD extractor springs & CRANE O-rings

  1. #151
    Join Date
    May 2006
    Location
    VA/OH
    Posts
    29,630
    Feedback Score
    33 (100%)
    Quote Originally Posted by VA_Dinger View Post
    Has anybody had any expierences were they felt the need for CRANE bolt upgrades in a 6.8 mid-length?
    The Crane upgrades were designed for guns with carbine gas systems (espeically the 10.5 types).

    Since middy guns do not run as fast and hard as SBR's, I do not believe that you need to the 5 coil spring and Crane O-Ring. I still like to use the black extractor inserts though.

    Now if your 6.8 is over gased (which is entirely possible) and you are having extraction issues, you might want to look at adding an O-Ring.


    C4

  2. #152
    Join Date
    Jan 2010
    Posts
    61
    Feedback Score
    0
    Is anyone familiar with M&A? I found the D fender and spring parts at a decent price but the product detail does not say who makes or what their springs are made of. If I replaced the springs and added the D ring would I be good to go?

  3. #153
    Join Date
    Jan 2010
    Posts
    61
    Feedback Score
    0
    I wrote to M&A and they replied. My original message to them is at the bottom. Their answer seemed kind of vague to me. Is spring steel with a black insert and a D fender adequate for a reliability upgrade or should I go with Wolff springs or another kit? Do I just need to replace the ejector spring and add a D fender or O ring? Or should I replace everything on the bolt carrier?


    On Feb 09, 2010, at 1:43 PM, Info @ M&A wrote:

    Quote Originally Posted by info@mapartsinc.com
    They are spring steel. We use military contractors.

    Thank you / Have a great day


    ----- Original Message -----
    From: LongRider
    To: info@mapartsinc.com
    Sent: Tuesday, February 09, 2010 2:58 PM
    Subject: Contact Form From mapartsinc.com


    The extractor / Ejector spring products listed at http://www.ar15m16.us/products.asp?c...345&subTwo=385 does not indicate who makes them or what they are made of. Could you please enlighten me as to who makes them and what they are made of. Thank you for your time and consideration

  4. #154
    Join Date
    Jan 2008
    Location
    AZ-Waging jihad against crappy AR's.
    Posts
    24,902
    Feedback Score
    104 (100%)
    M&A parts has been discussed here before. I would stick with a quality manufacturer when it comes to extractor springs/ inserts, etc...

    Quote Originally Posted by LongRider View Post
    I wrote to M&A and they replied. My original message to them is at the bottom. Their answer seemed kind of vague to me. Is spring steel with a black insert and a D fender adequate for a reliability upgrade or should I go with Wolff springs or another kit? Do I just need to replace the ejector spring and add a D fender or O ring? Or should I replace everything on the bolt carrier?


    On Feb 09, 2010, at 1:43 PM, Info @ M&A wrote:



    Owner/Instructor at Semper Paratus Arms

    Facebook: https://www.facebook.com/SemperParatusArms/

    Semper Paratus Arms AR15 Armorer Course http://www.semperparatusarms.com/cou...-registration/

    M4C Misc. Training and Course Announcements- http://www.m4carbine.net/forumdisplay.php?f=141

    Master Armorer/R&D at SIONICS Weapon Systems- http://sionicsweaponsystems.com

  5. #155
    Join Date
    Jan 2010
    Posts
    61
    Feedback Score
    0
    Quote Originally Posted by Iraqgunz View Post
    M&A parts has been discussed here before. I would stick with a quality manufacturer when it comes to extractor springs/ inserts, etc...
    Thanks for the heads up read the whole thread and must of missed it

  6. #156
    Join Date
    Jul 2006
    Posts
    2,705
    Feedback Score
    0
    You can't identify extractor springs by the number of coils. The drawings do not even specify the number of coils except as a reference which is variable. That means the spring maker tests the spring and adjusts the coils and OAL to achieve the lbs of force that is specified on the drawing. Also, each brand may use its own wire thickness and a different OAL.

    I just measured every extractor spring Brownell's sells. I can say there is some scary stuff there.

    The USGI spring from 1971 had a stress/strain ratio under 50% when compressed to 0.112. Those can last 18,000+ rounds. True, they only have 4 lbs of force at this height, but the o-ring will add in the extractor tension without having to resort to an extra power spring.

    Why is an extra power spring bad? Because more force means more stress. Some of the springs from Brownell's had stress/strain ratios above 80%! If you monkey around with extra power springs, then change them every 1500 rounds.

    The new M4 spring that is Copper colored is pretty interesting. It has exactly double the force of the earlier spring but does not have a huge amount of additional stress. If I were going to run a spring without an o-ring, I would use the new Colt M4 spring.

    Or use an old-style 0.022 wire diameter USGI (people call this the '4 coil') with an o-ring and it should last the life of the bolt (but since it is cheap, might as well change it at 5000 rounds).


    Now here is why I feel Chrome Silicon magazine, action, and extractor springs are BS:

    A magazine with the standard 17-7 stainless spring may be stored fully loaded with 30 rounds indefinitely. Note that Chrome Silicon springs will not resist taking a set better than MIL-STD 17-7 magazine springs. A spring 'takes a set' when it reaches the proportional fatigue limit. The higher the tensile strength, the more it can resist taking a set. Here are the material properties of three premium materials*:

    Chrome Silicon:
    Minimum Tensile Strength: 235-300 psi
    Max Operating Temp: 475F
    Fatigue Properties: Fair

    Music Wire ASTM A228
    Minimum Tensile Strength: 230-399 psi
    Max Operating Temp: 250F
    Fatigue Properties: Excellent

    17-7 PH Stainless
    Minimum Tensile Strength: 235-335 psi
    Max Operating Temp: 650F
    Fatigue Properties: Good

    As you can see, all three materials are about the same with the main difference being temperature, corrosion, resistance, and price. 17-7 costs 2.75 times as much as chrome-silicon ** so it only makes sense to give up the corrosion resistance if the price is much lower and you are not worried about rust.

    The CS spring makers would have to believe they have something new and better and that the military is just behind the times or penny-pinching for not using it. That is not true, as CS is far cheaper than stainless springs. The reason the military has not changed is likely because they have actual engineers who work with facts.


    *
    http://optimumspring.com/technical_reso ... _wire.aspx
    http://optimumspring.com/technical_reso ... _wire.aspx
    http://optimumspring.com/technical_reso ... _wire.aspx
    http://www.docstoc.com/docs/4884305/Typ ... CIFICATION
    **
    Fundamentals of Spring Design from the Spring Manufacture's Institute, page 13, table SM-8
    Last edited by rsilvers; 08-05-10 at 22:28.

  7. #157
    Join Date
    Jul 2006
    Location
    Paradise
    Posts
    828
    Feedback Score
    0
    So, who sells the Gold (Colt) springs?
    "So have your buddy get a box of stray cats and try to get a good sight picture while he is throwing the cats at you... naked." - KLD

    Get yours news at Presscheck.org!

  8. #158
    Join Date
    Jan 2008
    Location
    AZ-Waging jihad against crappy AR's.
    Posts
    24,902
    Feedback Score
    104 (100%)
    Brownells may have them. I got mine from Specialized Armament at the last Phoenix gun show.

    Quote Originally Posted by JLM View Post
    So, who sells the Gold (Colt) springs?



    Owner/Instructor at Semper Paratus Arms

    Facebook: https://www.facebook.com/SemperParatusArms/

    Semper Paratus Arms AR15 Armorer Course http://www.semperparatusarms.com/cou...-registration/

    M4C Misc. Training and Course Announcements- http://www.m4carbine.net/forumdisplay.php?f=141

    Master Armorer/R&D at SIONICS Weapon Systems- http://sionicsweaponsystems.com

  9. #159
    Join Date
    Jan 2007
    Location
    WA
    Posts
    599
    Feedback Score
    1 (100%)

  10. #160
    Join Date
    Jun 2006
    Posts
    6,028
    Feedback Score
    13 (100%)
    There is something to be said about buying an LE6920 and not ****ing with it.

Page 16 of 21 FirstFirst ... 61415161718 ... LastLast

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
  •