BCG Recommendation needed

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  • Peregrine
    Bloodstained
    • Dec 2017
    • 30

    #61
    Anothet question for the Horde. What is the advantage of a chrome lined gas key? I've read reviews of BCGs where people gripe that the gas key isn’t chrome lined. It seems like a chrome lined gas key is milspec. Am I missing something here?

    Also, do chrome BCGs (e.g. Young Mfg.) cause more wear to the upper receiver as opposed to BCGs with other finishes (i.e. phosphate, nitride, DLC)?
    Last edited by Peregrine; 01-03-2018, 03:33 AM.
    Gun control means using both hands.

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    • Torquaholic
      Bloodstained
      • Nov 2017
      • 46

      #62
      Originally posted by Peregrine View Post
      Anothet question for the Horde. What is the advantage of a chrome lined gas key? I've read reviews of BCGs where people gripe that the gas key isn’t chrome lined. It seems like a chrome lined gas key is milspec. Am I missing something here?

      Also, do chrome BCGs (e.g. Young Mfg.) cause more wear to the upper receiver as opposed to BCGs with other finishes (i.e. phosphate, nitride, DLC)?

      As far as I understand it, the benefit of Chrome in the gas key and inside bore of the Bolt carrier (where the bolt and rings ride) is that the chrome plating helps mitigate the corrosion that would otherwise take place on bare steel when exposed directly to the combustion gasses coming out of the gas tube. I think that any of the new coatings may indeed provide the same benefit, but don't quote me on that. The chrome lining thing is tried and true over decades, which is why it is probably Mil-spec.

      I don't know if there are any studies on the longevity of Chrome lining vs Melonite/Nitride vs NiB etc. in these parts, but it seems to me that there are two sides to the argument when it comes to coating the carrier:

      A coated carrier requires less lube to function smoothly. A Phosphate carrier is more porous and needs more lube than a coated carrier, and it will also retain more lube because of the porosity. Run a phosphate carrier wet and you shouldn't have an issue. Run a ton of lube on a coated BCG and watch it slide off, kind of a waste of lube if you ask me. The nice thing about a coated carrier is that you don't have to apply lube as often as with a phosphate carrier.

      How much wear between parts you get is a direct function of how much lube you run and what your round count is, or at least that's the way I see it.

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      • Lightscout
        Unwashed
        • May 2017
        • 14

        #63
        One thing I didn't see mentioned much was the Ballistic Advantage 6.5 bcg. I picked up one of their barrels from Monmouth during a sale and was planning on using the BA bcg with the BA barrel. It's a 20" barrel with rifle gas; any reason to be suspect of their bcg?

        Updated: Thanks for the reply Torq! Just saw the 2018 Grendel Deals thread and picked up a Toolcraft bcg from Monmouth for ~$95. Will start with that.
        Last edited by Lightscout; 01-18-2018, 04:52 PM.

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        • Torquaholic
          Bloodstained
          • Nov 2017
          • 46

          #64
          I haven't heard anything bad about BA BCG's. The specs look right.

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          • blackholegun
            Bloodstained
            • Oct 2017
            • 59

            #65
            BA BCG's are solid, have built two guns with them and have had 0 problems
            Everything I enjoy doing is either illegal, immoral or, just to damn expensive

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            • Crusty
              Warrior
              • Dec 2017
              • 237

              #66
              I've purchased a Maxim and an Alexander and the Alexander is the clear winner of the two. I had to use an enhanced firing pin in the Maxim to get enough FP depth to eliminate light strikes on all ammo. When I sell that upper I'm not going to include the Maxim bolt and I'll tell the buyer to buy an Alexander bolt for it. The JP bolt is the Mercedes of Grendel bolts and if I had the bucks that's what I'd buy. Just about any nitrided mil-spec carrier seems to work fine.
              I'll be yer Huckleberry.

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              • ToeheadAR
                Bloodstained
                • Jan 2018
                • 39

                #67
                From what Iv'e read the finish of the NiB BCG will stain or look dirty when it's clean due to the heat but it keeps its lubricity. I have a Melonite BCG in my standard AR15 and I probably could get away with never cleaning it but I at least wipe it down each use. But it's a piston gun.

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                • LRRPF52
                  Super Moderator
                  • Sep 2014
                  • 8569

                  #68
                  Originally posted by Peregrine View Post
                  Anothet question for the Horde. What is the advantage of a chrome lined gas key? I've read reviews of BCGs where people gripe that the gas key isn’t chrome lined. It seems like a chrome lined gas key is milspec. Am I missing something here?

                  Also, do chrome BCGs (e.g. Young Mfg.) cause more wear to the upper receiver as opposed to BCGs with other finishes (i.e. phosphate, nitride, DLC)?
                  Hard chromed gas keys maintain their dimensional specs better under heat, and this is critical because a gas seal with the gas tube flange is essential for reliable function of the AR15-one of the most overlooked aspects of the rifle.

                  Hard chromed carriers don't wear the upper anymore than phosphate per se. The biggest influence on wear that I've seen is tool marks. No matter if the carrier is chromed, NiB, TiN, or whatever flavor of the month of Gucci coating, if the tool marks haven't been finished with a smoothing process before coating, the carrier will have a rough texture to it.

                  This is more critical inside the carrier bore for the bolt than the carrier rails.

                  If the inside of the carrier bore has rough tool marks (this has happened even with the top line AR15 manufacturers in certain batches), it will shred the gas rings quickly, causing loss of gas seal in the Stoner internal expansion system, resulting in short-stroking malfs.

                  No mater what carrier you're looking at, inspect the bolt bore for rough tool marks. I have a PSA carrier around here somewhere that has that problem. You can feel it grinding on the gas rings when the bolt telescopes inside the carrier.

                  As to carrier rails, I personally like to polish them if they are rough. Most nitrided carriers I have don't need that done to them though, as the surface is very smooth.

                  Not all carriers are created equally. There are variations out there that can mean the difference between a reliable gun, an accurate gun, or not.
                  NRA Basic, Pistol, Rifle, Shotgun, RSO

                  CCW, CQM, DM, Long Range Rifle Instructor

                  6.5 Grendel Reloading Handbooks & chamber brushes can be found here:

                  www.AR15buildbox.com

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                  • Jester
                    Unwashed
                    • Feb 2018
                    • 2

                    #69
                    I would like to also adding a manufacturer to you go to list. St. Croix Tactical makes excellent BCGs/Bolts in several price ranges and materials & coatings. I have several ARs and all have a version of SCTs BCG/Bolts. They also offer a Lifetime Warranty & free shipping. Check them out and give them a go.

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                    • longbow62
                      Bloodstained
                      • Feb 2018
                      • 39

                      #70
                      I have a JP FMOS in my .223 and it is a work of art. Super slick and have had nothing stick to mine. Everything just wipes off the thing. It feels like it's made of glass it's surface is so slick. It looks brand new after a least a 1000 rounds but I do clean often and run it very wet. I am so impressed I will be buying another for the Grendel I am putting together.

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                      • bacjac
                        Unwashed
                        • Feb 2018
                        • 1

                        #71
                        I am kind of new at this, but wouldn't an adjustable gas block slow down the BCG so it would unlock and run smoothly?

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