Page 3 of 8 FirstFirst 12345 ... LastLast
Results 21 to 30 of 75

Thread: one-piece gas rings and M4A1

  1. #21
    Join Date
    Aug 2007
    Location
    Tennessee
    Posts
    912
    Feedback Score
    0
    Just to clarify,gota new battery for the Mahr digital caliper.Thomas M4's specs are also what Ive got on the Midway/DPMS Mcfrarland rings,.5030" on the money.Confirmed with a old Fowler dial caliper and also got .503".

    Later I'll pull one of the bolts and see what a used Mcfarland measures just to be curious..


    ETA
    I pulled two of my LMT bolts with McFarland rings.One is .4970" and the other is .4985"....round counts on each is approaching 3,000.
    That said the rings have worn in but still offer enough tension that they will pass a standard gas ring inspection.Certainly not loose.
    As a note one of the LMT carriers has a rather loose bore compared to the others I have(particularly at the bolt tail),and it varies from carrier to carrier to a certain extent.
    Of the carriers I have,the Armalite and DD have the tightest,smooth and most consistent bores of them all(per feel and eye ball),both in the gas ring chamber,bolt tail and bolt bearing band surface.
    So yeah I can see there is a variation in the carrier bore diameters,and finish,in the samples I have on hand.
    Last edited by Blankwaffe; 02-27-10 at 22:28. Reason: ETA
    Glock Certified Armorer
    Armed Protective Services II

  2. #22
    Join Date
    Feb 2009
    Location
    somewhere along the Rio Grande
    Posts
    75
    Feedback Score
    20 (100%)
    Hmm, interesting. I ordered a few from G&R, so they should be here pretty quick. I'm betting, though, that they'll measure .503.

    I'm way out of my lane on this one, because I'm not all that familiar with bolt carrier manufacturing processes. I wonder, though, if the thickness of the chrome lining inside the bolt carrier may vary from different manufacturers and may be leading to the results I'm seeing?

    Any thoughts?
    Last edited by patrolman; 02-27-10 at 20:22.

  3. #23
    Join Date
    Nov 2008
    Location
    Pittsburgh Area, PA.
    Posts
    869
    Feedback Score
    0
    I ordered 3 McFarland gas rings from Grant and installed one set in my Charles Daly M4 and the carrier will not stand on bolt with them installed. I have not measured them. So far they have only been used one time at the winter study group shoot with The_Katar, maybe 100 rounds tops that day I would guess. Maybe with the seamless design the tension is not required?
    I save money using AMSOIL full synthetic lubricants. Do you?
    http://www.lubedealer.com/DiscountPowerParts/home.aspx

  4. #24
    Join Date
    Apr 2008
    Location
    NW IL
    Posts
    156
    Feedback Score
    6 (100%)
    Quote Originally Posted by patrolman View Post
    the thickness of the chrome lining inside the bolt carrier may vary from different manufacturers
    That's what I'm starting to wonder about...

  5. #25
    Join Date
    Feb 2009
    Location
    somewhere along the Rio Grande
    Posts
    75
    Feedback Score
    20 (100%)
    Maybe with the seamless design the tension is not required
    Larry,

    I was thinking the same thing initially. However, I tried running one of the bolts with the loose rings installed and the gun short-stroked like crazy on full auto. Was slightly more behaved on semi, but still short-stroked three times on 30 rounds. Re-installed the 3-ring setup and no more short stroking. I came to the conclusion that the loose rings were allowing too much gas blow-by. Too bad, really, because I want these one-piece rings to work.

  6. #26
    Join Date
    Aug 2007
    Location
    Tennessee
    Posts
    912
    Feedback Score
    0
    Quote Originally Posted by danish View Post
    The carrier collapses very easily around the bolt. The gun has always felt under-gassed and thought these new rings would help but apparently the carrier is out of spec...The rings all measure the .503 previously posted. I did shoot it with the new rings and it did seem to perform better...
    I'd call RRA and let them inspect/replace that carrier under warranty even if you do upgrade to a BCM.Remember a few months ago good carriers no matter the brand or style was rare as hounds teeth and selling at a premium.So if you think the one you have is out of spec,I'd let them give me a new one in its place.
    Last edited by Blankwaffe; 02-27-10 at 22:38. Reason: ETA
    Glock Certified Armorer
    Armed Protective Services II

  7. #27
    Join Date
    Apr 2008
    Location
    NW IL
    Posts
    156
    Feedback Score
    6 (100%)
    The BCG is five years old with a about 500-600 rounds a year shoot with it or 3,000 total. This used to me my three-gun AR and always shot good ammo which never really showed any issues. I've now been going thru replacing items for a more reliable AR to run all ammo and Wolf always seemed under-powered and wouldn't run reliablely. I figured the rings were bad after trial-and-error so that's when I installed the McFarlands to eleviate the issue. I can say it has but this is at a low round count which more shooting needs to be done to make sure....

  8. #28
    Join Date
    Apr 2009
    Location
    FL -Where it's summer 10.5 months out of the year
    Posts
    4,114
    Feedback Score
    17 (100%)
    Guys please remember that the carrier-stand test is only good when the carrier and the gas rings are bone-dry (i.e. clean). If they are lubed, they should NOT prevent the carrier from collapsing. Same thing with vehicle piston rings; they seal BEST when wet...they also MOVE best when wet. I wouldn't worry if your gun has a good (read: in spec) bolt and bolt-carrier and doesn't malf. I use mcFarland gas rings in my BCM middy 16" upper with zero issues....and I use a heavy Spike's ST-T2 buffer and a Tubbs Flat-wire buffer spring. Works great with .223 el-cheapo stuff and 5.56. I use a CMT bolt and carrier with the single piece rings. Good luck on resolving this issue.

  9. #29
    Join Date
    Jun 2006
    Location
    Niantic CT
    Posts
    1,964
    Feedback Score
    6 (100%)
    The proper way to test the gas rings is to remove the firing pin and cam pin then hold the carrier with the bolt pointed to the ground. If the bolt fall out then the gas rings need to be replaced.

    Chapter 3 page 0011-6 of the TM 9-1005-319-23&P
    Last edited by Iraqgunz; 03-02-10 at 00:27.

  10. #30
    Join Date
    Jan 2009
    Location
    Vermont, USA
    Posts
    842
    Feedback Score
    0
    I had the same issue with the McFarland one peice, did'nt affect function so I ran it anyway. Maybe that's how my firing pin got bent??? As an aside, try running a bolt without any gas rings whatsoever, lo and behold it still functions without issue.

Page 3 of 8 FirstFirst 12345 ... 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
  •