Spare BCG

View Latest Activity

Viewing 28 reply threads
  • Author
    Posts
    • #109173
      Virgil Kane
      Participant

        I have name brand ones (BCM, Spikes) in my AR’s and I bought a couple of inexpensive backups for around $100 each. One came from AIM and one came from a LGS.

        Everything looks and feels right on the cheap ones until I get to the firing pin retaining pin. Replacing it takes a pair of pliers and all manor of twisting and pushing. The ones on the better BCG’s slip right in. They seem to run fine in the weapons, but that’s running a few mags through it a the range and not pounding the hell out of it.

        Is this a situation of get what you pay for?

      • #109174
        Aerohawk
        Participant

          I bought a spare Daniel defense one for my MP15 and it runs great. Worth the extra 100 if you ask me.

        • #109175
          dnb
          Participant

            Does not sound good. Call vendor, they may assist. They might break in. Put them thru the ringer as they may be gtg for spares.

            Put 1000 rounds though each. If it checks out inspection wise and passes the test, stick the spare bolt, cam pin, retaining pin, and firing pin in the pistol grip of your stick with a small bottle if lube. Job done. If they don’t pass, next…

            I’ve had decent experience with psa prem bcgs for 70-80 bucks to use as spares / range / training. One nitride one was a bust, fit wise and it failed 1500-2000 rounds.

          • #109176
            Weber
            Participant

              It has been said many times before…you get what you pay for. Stick with BCM, Colt, LMT for your BCGs. High QC is what you are paying for. However, there are also a few other high quality “manufacturers” out there that are worth purchasing.

            • #109177
              RRS
              Participant

                I AM NOT AN EXPERT. That said I have a Rock River Arms upper that came with a BCG that was chromed and the one thing I can say is that it is easy to clean.

              • #109178

                I have had some trouble with proper staking of the gas key on two aim surplus bcg’s. restaked them and they were fine. still running.

                spikes and bcm bcg’s are great

              • #109179
                Virgil Kane
                Participant

                  I’ll either sell them on arfcom or just run them and see what fails. The biggest issue I see with running them is a loose gas key could bend a gas tube and I hate replacing them.

                • #109180
                  JohnnyMac
                  Participant

                    It’s been so far so good with the PSA premium bcg’s I’ve gotten (low round counts right now), which are the same price when on sale. Yes, I have found the retaining pin kinda hard to get in, but nothing crazy. Staking has looked solid.

                    I’ve had good luck with a WMD Nib bcg that came with a used DD MK18 upper, but YMMV.

                  • #109181
                    First Sergeant
                    Moderator

                      Some of you make my head hurt.

                      Stay away from the junk. The money you think you are saving is a mind game you are playing with yourself.

                      If you buy from one of the good known manufacturers, you don’t need to do a 1000 round test. It will run because of the QA/QC process. Weber is right.

                      Coated BCG’s area gimmick to take your money.

                      How many times do I have to repeat myself?

                      FILO
                      Signal Out, Can You Identify
                      Je ne regrette rien
                      In Orbe Terrum Non Visi

                    • #109182
                      wheelsee
                      Participant

                        Some of you make my head hurt.

                        Stay away from the junk. The money you think you are saving is a mind game you are playing with yourself..

                        How many times do I have to repeat myself?

                        Some of us are slow learners…..have been all my life. Pops always told me the stove was hot and would burn me…..I kept touching it thinking he may have turned it off….by the 10th time, I figured he was right. So we do learn, just slowly.

                      • #109183
                        Virgil Kane
                        Participant

                          Anybody want to buy a couple of BCG’s?LOL

                          I’ll use them at the range and see how they do.

                        • #109184
                          JohnnyMac
                          Participant

                            Some of you make my head hurt.

                            Stay away from the junk. The money you think you are saving is a mind game you are playing with yourself.

                            If you buy from one of the good known manufacturers, you don’t need to do a 1000 round test. It will run because of the QA/QC process. Weber is right.

                            Coated BCG’s area gimmick to take your money.

                            How many times do I have to repeat myself?

                            No worries 1SG, the WMD NiB BCG is an orphan, it sits on a shelf.

                          • #109185
                            trailman
                            Participant

                              I have two PSA premium BCGs that I got about three years ago for complete spares. I have a few rounds on them to break then in but so far so good. I need a multi-tool to get the pin out. I could probably fish it out with a nail if needed. Its firm but not tight.

                            • #109186
                              First Sergeant
                              Moderator

                                @dnb, Give me a good reason for a 1000 round test on a BCG.

                                FILO
                                Signal Out, Can You Identify
                                Je ne regrette rien
                                In Orbe Terrum Non Visi

                              • #109187
                                dnb
                                Participant

                                  @dnb, Give me a good reason for a 1000 round test on a BCG.

                                  Commissioning.

                                  https://en.m.wikipedia.org/wiki/Project_commissioning

                                • #109188
                                  First Sergeant
                                  Moderator

                                    @dnb, Give me a good reason for a 1000 round test on a BCG.

                                    Commissioning.

                                    https://en.m.wikipedia.org/wiki/Project_commissioning

                                    No. That has nothing to do with a 1000 round test on a BCG.

                                    If you get your parts and rifles(pistols also) from manufacturers that are known for putting out quality products, there is no reason for a 1000 round test. The reason? They have been in business for so long and their products are known to run reliably right out of the box. The reason is their QA/QC process.

                                    Do those companies occasionally put out a lemon? Yes. But the odds are in your favor that you wont get one.

                                    I would buy a spare BCG from Colt, BCM, Larue, LMT or Knights and have no issue with oiling it up, putting it in a rifle and going to class with confidence that I am not going to have any issues. If I knew that I was going somewhere that my life depended on it, I would put at least a basic load of ammo through it. That is 210 rounds. 7 magazines. That’s it.

                                    Stop putting out BS information as gospel. Their is enough of that on the rest of the internet.

                                    Where did you learn the 1000 round test from?

                                    FILO
                                    Signal Out, Can You Identify
                                    Je ne regrette rien
                                    In Orbe Terrum Non Visi

                                  • #109189
                                    BrothersKeeper
                                    Participant

                                      Hey Scott, I purchased a Daniel Defense ar for combat leadership last year. It was built for more of the 3 gun crowd so it has a compensator on it, very light trigger and an 18” heavy barrel. I don’t have any extra parts for it yet. Was considering getting an extra bcg from Daniel defense and replacing the compensator with an A2 birdcage. Also, what parts kit would you reccomend for all the common springs and bits that need replacing now and then. Thanks.

                                    • #109190
                                      First Sergeant
                                      Moderator

                                        Hey Scott, I purchased a Daniel Defense ar for combat leadership last year. It was built for more of the 3 gun crowd so it has a compensator on it, very light trigger and an 18” heavy barrel. I don’t have any extra parts for it yet. Was considering getting an extra bcg from Daniel defense and replacing the compensator with an A2 birdcage. Also, what parts kit would you reccomend for all the common springs and bits that need replacing now and then. Thanks.

                                        BCG from DD is fine. Yes to the standard A2 birdcage.

                                        A standard LPK(Lower Parts kit) is what you need. Just make sure you get one from a good company.

                                        FILO
                                        Signal Out, Can You Identify
                                        Je ne regrette rien
                                        In Orbe Terrum Non Visi

                                      • #109191
                                        Abacus
                                        Participant

                                          To really get the number of rounds needed to “catch” a lemon (sample size to us nerds) right I would need information on not just one or two BCGs but a representative sample of the total population of parts. Then we could build a distribution and or a reliability curve and I could advise you on the minimum number of rounds for a given level of statistical confidence and power. But even then I could not promise we would not miss one due to random chance being a bitch. Or rather type I and Type II errors are a bitch random chance is just entropy being an uncaring dick.

                                          I don’t know if that number would be 1,000 rounds, but I doubt it. The number feels to round to have any real science behind it. Note I said it “feels to round” so take that comment with the salt it requires. It could be less, or it could be more. I don’t know.

                                          Generally the bigger your sample size the better up to a point. But you can over sample and generate false certainty (artificially inflated or deflated P values for the nerds on the house). You also can reach a point of diminishing returns in testing and ammo ain’t free.

                                          I do this stats stuff for a living, and I only use a feel good number for my own personal weapons stuff. Truth be told I use similar rules of thumb at work too, at least initially. My feel good number is 500 rounds for a given configuration, but it is a feel good number not a real test. I think I stole that figure from a Reid Hendricks video about testing if various handgun loads cycle properly in carry guns. He probably either either pulled it from thin air or stole it from someone else who did. But, I like the number and feel okay with it. But again that is more feelz not math.

                                          I wonder what the Army has in DTIC about this? Maybe a lit search is required…

                                        • #109192
                                          First Sergeant
                                          Moderator

                                            @Abacus, Yes, you would need a large sampling to do the test right but we already have that with the number of BCG’s in the wild.

                                            As I stated above, I would have no problem dropping a brand new Colt, BCM, DD or LMT BCG into a rifle and having confidence that it would work. If I was going in harms way I would a least put a basic load(210 rounds) through it.

                                            FILO
                                            Signal Out, Can You Identify
                                            Je ne regrette rien
                                            In Orbe Terrum Non Visi

                                          • #109193
                                            Abacus
                                            Participant

                                              I have done some thinking and Fist Sergeant is right. I don’t have the data so I can’t set a good number but 210 is as good as any and cost less than 1,000.

                                              Estimates on the rounds to failure distributions probably exist within the QA departments of companies like Colt and some of the other manufacturers. It could certainly be estimated from high volume shooter’s maintenance logs like the Army or the rental ranges in Vegas. I don’t have that data. We could build our own if somebody wants to send me a representative sample of the BCGs in question, 30 should do, and a couple pallets of ammo.
                                              The manufacturers First Sergeant mentioned fail less at least anecdotally.

                                              BCGs fail three ways, that I know of. Either they are out of dimensional specs and hang up in the gun, they are materially compromised and break, or something like that gas key comes loose and they stop working.

                                              The first and last failure mode should show up early. They probably amount for most of your early BCG failures. These are your lemons and represent the handful of parts out of the whole population that may slip through QA. This is especially true under batch sample inpection regimes. An every part everytime inspection system might have fewer failures make it through but at a higher cost.

                                              The second failure mode may not show up early. And, such failures point to a problem with the manufacturer’s materials or process or at least a lot. Testing for that failure mode is probably beyond the capabilitiy of the consumer. We can’t really do materials testing in most cases and are stuck trying to simply see if we can break it. Even then breaking one is not super useful since the thing we are testing is now broken and can’t be used. Additionally a single data point is not very useful for making predictions and does not tell us much about the next BCG we might buy from that manufacturer.

                                            • #109194
                                              JohnnyMac
                                              Participant

                                                Not that it matters (IE just buy a bcg from one of those 1SGT mentioned!), but this stuff isn’t hard to find.

                                                Some stuff I found:

                                                Test Operations Procedure- Small Arms
                                                USMC IAR Reliability Data
                                                AMSAA Improved Small Arms Testing Slideshow

                                                The best thing to do is get to the VTC, and then practice regularly between classes.

                                                :whistle:

                                              • #109195
                                                Joe (G.W.N.S.)
                                                Moderator

                                                  I don’t think Abacus is disagreeing with First Sergeant’s advice.

                                                  Those that are paying attention know that the recommended spare parts are doing these numbers internally, hence the vast majority of the time buying from them is worry free. This is why we pay a higher price for piece of mind.

                                                  I am at stats conference right now so I will pick some brains. It may not matter, but it will be a fun project.

                                                  It seems Abacus enjoys his work; something many can’t say, and we are better off because of people that like doing this detail work.

                                                  Now if I am wrong and Abacus is just being argumentative, we can string him up later! ;-)

                                                  There is a lot that goes into making quality products, particularly BCG’s. For those interested the data is out there, for the rest purchase the recommender parts.

                                                • #109196
                                                  JohnnyMac
                                                  Participant

                                                    @Joe I just reread my post, and “it came out wrong”. @Abacus no shade from me. I’m actually “a math guy” myself, and even spent some time as a reliability engineer.

                                                    My point was, if you practice with your rifle, and keep some spare parts on hand, there’s nothing to worry about.

                                                  • #109197
                                                    Joe (G.W.N.S.)
                                                    Moderator

                                                      JohnnyMac no problems from my point of view, fog of internet. ;-)

                                                    • #109198
                                                      Abacus
                                                      Participant

                                                        I rewrote my response. I am not arguing with anybody. I am simply pontificating on sample sizes and the science of test. It’s my jam and I had to sit through some really bad presentations today so I had time to think about it.

                                                      • #109199
                                                        Robert
                                                        Participant

                                                          @abacus, Yes, you would need a large sampling to do the test right but we already have that with the number of BCG’s in the wild.

                                                          As I stated above, I would have no problem dropping a brand new Colt, BCM, DD or LMT BCG into a rifle and having confidence that it would work. If I was going in harms way I would a least put a basic load(210 rounds) through it.

                                                          Thanks 1st Sargent for this, saved me starting a new thread.

                                                          Although it pains me to admit this- at CQB last weekend my BCG disappeared. I believe when we were pulling through the barrels in the parking lot it fell off the truck there. The pull through wasn’t going easily and we had to bounce the barrel on the tailgate to get it to go through. I’m guessing their is a BCG on the ground near the porta potty in the parking lot. It will be late Spring at the earliest before I’m back and I assume it will be next to useless by then.

                                                          Twice as painful for me as an AK guy is having to buy a replacement for it, knowing damn well with UTM going the way of the dinosaur at MVT (only reason I bought AR’s again) that I will get little use of the thing.

                                                          These quality BCG’s 1st Sargent spoke of, will they interface o.k. with a cheap M&P 15?

                                                          Any that I buy online should come staked already correct? Anything else to check when receiving?

                                                        • #109200
                                                          First Sergeant
                                                          Moderator

                                                            @abacus, Yes, you would need a large sampling to do the test right but we already have that with the number of BCG’s in the wild.

                                                            As I stated above, I would have no problem dropping a brand new Colt, BCM, DD or LMT BCG into a rifle and having confidence that it would work. If I was going in harms way I would a least put a basic load(210 rounds) through it.

                                                            Thanks 1st Sargent for this, saved me starting a new thread.

                                                            Although it pains me to admit this- at CQB last weekend my BCG disappeared. I believe when we were pulling through the barrels in the parking lot it fell off the truck there. The pull through wasn’t going easily and we had to bounce the barrel on the tailgate to get it to go through. I’m guessing their is a BCG on the ground near the porta potty in the parking lot. It will be late Spring at the earliest before I’m back and I assume it will be next to useless by then.

                                                            Twice as painful for me as an AK guy is having to buy a replacement for it, knowing damn well with UTM going the way of the dinosaur at MVT (only reason I bought AR’s again) that I will get little use of the thing.

                                                            These quality BCG’s 1st Sargent spoke of, will they interface o.k. with a cheap M&P 15?

                                                            Any that I buy online should come staked already correct? Anything else to check when receiving?

                                                            They should work fine in your AR.

                                                            They should all come properly staked. Of course inspect it when you get it.

                                                            FILO
                                                            Signal Out, Can You Identify
                                                            Je ne regrette rien
                                                            In Orbe Terrum Non Visi

                                                          • #109201
                                                            Hessian
                                                            Participant

                                                              P.O.F makes a very nice and expensive bolt carrier group that is machined from a solid piece of alloy steel, eliminating the need to stake the gas key and deleting the ability for gas key screws to come loose under operation.

                                                              If anyone has cash that is burning a hole in their pocket.

                                                          Viewing 28 reply threads
                                                          • You must be logged in to reply to this topic.