View Full Version : Best BCGs currently available?
I haven't been able to follow new products or advances in technology in the AR world lately, and I'm finally getting around to ordering a BCG to finish off a build. What are the best options out there for BCGs these days? Is it still BCM or LMT, or have new players come onto the scene?
The rifle in need of a BCG has a 16" midlength Noveske N4 barrel with Switchblock and a Vltor A5 RE with the A5H4 buffer (I may need to lighten that, but I will tune as needed) and a standard BCM rifle spring. A Specwar or Omega suppressor is also planned as an attachment. The goal is reliability and low recoil, in that order. I don't shoot reloads or Russian ammo, so Federal 55gr. FMJ .223 bulk is the weakest load it needs to cycle.
Following my original plan, I currently have a LMT Enhanced Carrier and a LMT standard bolt in my cart waiting for me to pull the trigger. I also already have a WMD NiB-X cam pin I planned to use along with a standard firing pin and firing pin retaining pin. Is this still a solid setup for my application or is there a better option that I am not aware of?
A complete BCM bolt carrier group is as good as it gets.
I have really been impressed with Azimuth's QPQ BCG. The machine work is second to none, it's easy to clean, basically it's a JP FMOS with the bolt QPQ'ed for 1/2 the price. I know of some out there with nearly 30K rounds on them, running fine.
Here's a recent "Best BCG" thread. You may find some info you're looking for.
https://www.m4carbine.net/showthread.php?t=171133
A complete BCM bolt carrier group is as good as it gets.
This ^
I think we have come full circle with all the chrome, Nib, dimpled blinged out BCG nonsense and are back to basics. DD, RA, BCM are all GTG!
BCM, Colt, Badger Ordnance, LMT, Daniel Defence
funkybassplayer
07-31-15, 17:30
I've got BCM, Spikes, and DD and all of them have worked flawlessly. My BCM has seen the most action so id recommend that if I had to get another
-BTO-
For most, it would be hard to argue against Colt and LMT BCGs as base components. Not saying that others cannot do well, it's just harder to argue against those. For individual components of those, more debates could be made.
Partially off topic, but coatings are a blessing and a curse all at the same time. In the end it seems harder to debate against using park or HC, depending on the process that results in the end product.
My favorite is . http://sionicsweaponsystems.com/store/product.php?id_product=74
Thank you for the replies. The general consensus seems to be the status quo, Colt, BCM, LMT and DD all highly recommended as expected.
In regards to the other recent "Best BCG" thread, and specifically the excitement over NiPTFE coating (NP3), I'm not convinced that is a good idea for a BCG, or any component subject to high temperatures. NiPTFE is only rated to 500 degrees Fahrenheit and my gut feeling is that the bolt sees higher temperatures than that. On that basis alone, I've personally ruled out Sionics and other NiPTFE BCGs unless someone can present a compelling argument why I'm wrong.
Hard chrome or Melonite treatment on the other hand does sound like a promising idea, although I have to wonder, if it's so great why haven't the aforementioned top dogs (Colt, BCM, LMT, and DD) released BCGs with hard chrome plating or Melonite treatments? I'd like to hear more opinions on the matter.
I have really been impressed with Azimuth's QPQ BCG. The machine work is second to none, it's easy to clean, basically it's a JP FMOS with the bolt QPQ'ed for 1/2 the price. I know of some out there with nearly 30K rounds on them, running fine.
This has peaked my interest. From what I found online, I believe you are referring to the Fathom Arms Enhanced BCG (http://www.rainierarms.com/fathom-arms-enhanced-bcg), but can you confirm that I'm understanding you correctly? I would absolutely love to know what has been 'Enhanced' about this BCG... Is it just the Melonite treatment and the redesigned tail section, or has the cam path or gas porting been altered as well, similar to the LMT Enhanced BCG?
Right now I'm torn between the Fathom Arms Enhanced BCG and my original plan (LMT E-Carrier, LMT standard bolt). I really like the fact that the lugs of the LMT bolt are radiused at the rear, and the E-Carrier has been shown to reduce recoil. However, I'm also digging the full Melonite treatment on the Fathom Arms E-BCG, and the fact that it is considerably cheaper than purchasing the individual LMT components separately. Can anyone offer more information to help me make up my mind?
Nightstalker865
08-01-15, 07:08
As others have stated BCM or Colt.
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Thank you for the replies. The general consensus seems to be the status quo, Colt, BCM, LMT and DD all highly recommended as expected.
In regards to the other recent "Best BCG" thread, and specifically the excitement over NiPTFE coating (NP3), I'm not convinced that is a good idea for a BCG, or any component subject to high temperatures. NiPTFE is only rated to 500 degrees Fahrenheit and my gut feeling is that the bolt sees higher temperatures than that. On that basis alone, I've personally ruled out Sionics and other NiPTFE BCGs unless someone can present a compelling argument why I'm wrong.
Hard chrome or Melonite treatment on the other hand does sound like a promising idea, although I have to wonder, if it's so great why haven't the aforementioned top dogs (Colt, BCM, LMT, and DD) released BCGs with hard chrome plating or Melonite treatments? I'd like to hear more opinions on the matter.
This has peaked my interest. From what I found online, I believe you are referring to the Fathom Arms Enhanced BCG (http://www.rainierarms.com/fathom-arms-enhanced-bcg), but can you confirm that I'm understanding you correctly? I would absolutely love to know what has been 'Enhanced' about this BCG... Is it just the Melonite treatment and the redesigned tail section, or has the cam path or gas porting been altered as well, similar to the LMT Enhanced BCG?
Right now I'm torn between the Fathom Arms Enhanced BCG and my original plan (LMT E-Carrier, LMT standard bolt). I really like the fact that the lugs of the LMT bolt are radiused at the rear, and the E-Carrier has been shown to reduce recoil. However, I'm also digging the full Melonite treatment on the Fathom Arms E-BCG, and the fact that it is considerably cheaper than purchasing the individual LMT components separately. Can anyone offer more information to help me make up my mind?
With the Noveske 16" with a LMT enhanced BCG, you'll likely end up in the A5H4 area with 5.56 gas port pressure ammo without a can. For similar combinations with the stainless Noveske barrels, I tend to recommend buying them long for their gas system and cut down on the barrel length. That way you can gas it more in the range of an A5H2 without a can, you can easily add more weight for dedicated suppressed that way. Starting off with the A5H4 limits choices.
SocomShooter
08-01-15, 18:35
After dismissing all the hype regarding the Fail Zero, chromed and TiNi BCG's, I went with a BCM for my latest build. Seems like everyone's trying to invent the wheel...but I don't wanna pay the money to be a guinea pig. In the end, I think I made a wise choice.
As others have stated BCM or Colt.
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I like the milspec profile bcg. The qpq eliminates cam pin wear almost entirely and the qpq on steel coefficient of friction is lower than steel on steel so the bolt lugs encounter less shear forces. The enhanced BCG does not have altered gas ports or cam pin path to my knowledge.
You may not agree with it, but it works. I am also pretty certain no BCG is going to approach anything near 500 degrees. We didn't wake up one day and decide to do NP3. We consulted with the people at ROBAR about it. The NP3 carrier group is something we have for a few years now and we several law enforcement agencies using them in the uppers and guns we build for them. Last week during a demo, a local agency ran 500 rounds through one of new SBR uppers with the reduced gas port in about 90 minutes. Bolt carrier simply wiped clean. If I didn't think the NP3 was solid, I wouldn't use them in my own personal weapons.
Thank you for the replies. The general consensus seems to be the status quo, Colt, BCM, LMT and DD all highly recommended as expected.
In regards to the other recent "Best BCG" thread, and specifically the excitement over NiPTFE coating (NP3), I'm not convinced that is a good idea for a BCG, or any component subject to high temperatures. NiPTFE is only rated to 500 degrees Fahrenheit and my gut feeling is that the bolt sees higher temperatures than that. On that basis alone, I've personally ruled out Sionics and other NiPTFE BCGs unless someone can present a compelling argument why I'm wrong.
Hard chrome or Melonite treatment on the other hand does sound like a promising idea, although I have to wonder, if it's so great why haven't the aforementioned top dogs (Colt, BCM, LMT, and DD) released BCGs with hard chrome plating or Melonite treatments? I'd like to hear more opinions on the matter.
This has peaked my interest. From what I found online, I believe you are referring to the Fathom Arms Enhanced BCG (http://www.rainierarms.com/fathom-arms-enhanced-bcg), but can you confirm that I'm understanding you correctly? I would absolutely love to know what has been 'Enhanced' about this BCG... Is it just the Melonite treatment and the redesigned tail section, or has the cam path or gas porting been altered as well, similar to the LMT Enhanced BCG?
Right now I'm torn between the Fathom Arms Enhanced BCG and my original plan (LMT E-Carrier, LMT standard bolt). I really like the fact that the lugs of the LMT bolt are radiused at the rear, and the E-Carrier has been shown to reduce recoil. However, I'm also digging the full Melonite treatment on the Fathom Arms E-BCG, and the fact that it is considerably cheaper than purchasing the individual LMT components separately. Can anyone offer more information to help me make up my mind?
Fatorangecat
08-02-15, 00:50
No love for the YM bolt carriers here? I have a Colt carrier I was considering swapping out but now I'm rethinking this.
You may not agree with it, but it works. I am also pretty certain no BCG is going to approach anything near 500 degrees. We didn't wake up one day and decide to do NP3. We consulted with the people at ROBAR about it. The NP3 carrier group is something we have for a few years now and we several law enforcement agencies using them in the uppers and guns we build for them. Last week during a demo, a local agency ran 500 rounds through one of new SBR uppers with the reduced gas port in about 90 minutes. Bolt carrier simply wiped clean. If I didn't think the NP3 was solid, I wouldn't use them in my own personal weapons.
I never intended to ruffle any feathers by my statement. I am usually pretty skeptical of most new products, so I hope my reservations about NP3 were not taken personally. Maybe BCGs don't see anywhere near 500 degrees and this coating is as excellent as the advertising makes it sound. Then again maybe not. I don't mean to sound lazy, but I'm at the point where I want to stop reading about fancy things on the interweb and finish this build up so I can start shooting it. I simply don't want to put forth the effort at this point in time to research NP3 to the point where I felt comfortable making a decision to use it, so I've crossed it off my list for now. That's all I was trying to say. If someone wishes to take the time to spoon feed me facts about why NP3 really is the new wonder coating, I'm all ears.
With the Noveske 16" with a LMT enhanced BCG, you'll likely end up in the A5H4 area with 5.56 gas port pressure ammo without a can. For similar combinations with the stainless Noveske barrels, I tend to recommend buying them long for their gas system and cut down on the barrel length. That way you can gas it more in the range of an A5H2 without a can, you can easily add more weight for dedicated suppressed that way. Starting off with the A5H4 limits choices.
Tom, I'm fine with the rifle being optimized for 5.56 unsuppressed. I am hoping the Switchblock will negate most of the increase in pressure when suppressed, and I'd rather err on the side of slightly overgassed when suppressed than slightly undergassed when unsuppressed and run into extraction issues. I would also like to have the ability to shoot .223 pressure loads reliably if possible.
What exactly causes the LMT E-Carrier to be so smooth and soft shooting? Does it have more to do with the altered cam path or the extra gas vents? If it is the altered cam path, would the increased carrier mass of the Fathom Arms E-Carrier accomplish the same thing? I'm just trying to understand the magic behind it to help myself make a more educated decision.
The combination that includes a proper port with the LMT enhanced carrier with the A5 action system alters the timing of events when compared to a conventional carrier and carbine action. The duration in time before bolt unlocking initiates is more, that allows the barrel to blow down in pressure more than a conventional carbine. The reduced pressure at that point has a few positive attributes. Another item is that there is more time present in the exhaust events before the key disengages the gas tube.
You get a smooth shooting system when you get a proper balance in the system. That could be done in many ways, that's not exclusive to any the mentioned components.
The combination that includes a proper port with the LMT enhanced carrier with the A5 action system alters the timing of events when compared to a conventional carrier and carbine action. The duration in time before bolt unlocking initiates is more, that allows the barrel to blow down in pressure more than a conventional carbine. The reduced pressure at that point has a few positive attributes. Another item is that there is more time present in the exhaust events before the key disengages the gas tube.
You get a smooth shooting system when you get a proper balance in the system. That could be done in many ways, that's not exclusive to any the mentioned components.
Correct me if I'm wrong, but couldn't the same be accomplished by increasing the reciprocating mass with a heavier buffer or carrier? I'm no expert on this, but I would think that a given amount of gas pressure would accelerate a heavier carrier more slowly than a lighter carrier, thus creating a similar increase in time before the bolt unlocks and the carrier key disengages the gas tube.
Yes, but then you need less gas to move less weight the other way. You get to much mass and spring then you get malfunctions from the system being out of balance.
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There are many balanced systems out there and many ways to make them. The amount of work used by the different types of systems to initially unlock the bolt and extract varies. That amount of work needed is in a direct relationship with how much the chamber depressurizes before those events occur.
An example of a balanced system could be an ultra light total reciprocating mass with a carbine type action spring, this system would take the most work, as it initiates the unlocking/extracting events at a higher chamber pressure. This would tend to be a less desirable balanced system, it is hard on parts, but it's common on race guns.
Another example could be an LMT enhanced carrier with an A5H2-A5H4 type of balanced system. This system would require less work, as it initiates the unlocking/extracting events at a lower chamber pressure. This would tend to be a more desirable balanced system, it's easy on parts (mostly), but some complain about an induced "wobble" from the higher mass.
When comparing the carbine action system to the A5/rifle system, a carbine action system cannot support the higher reciprocating mass that the A5/rifle system can support and maintain the balance. The additional mass adds to the delay and helps to reduce the amount of work needed.
When comparing the LMT enhanced carrier to a conventional type, the added delay in the cam pathway before unlocking initiates gives it more time for the barrel to blow down and require less work for the balance.
It seems to trend that the A5 with the enhanced carrier can have many benefits. There's some things I would have preferred to change on both items, but those are commercially available now. I would like to see some advances in the future that are actually put in production.
The LMT enhanced carrier and a heavier A5 even benefit 20" rifle gas 5.56 rifles.
jerrysimons
08-02-15, 23:41
With the Noveske 16" with a LMT enhanced BCG, you'll likely end up in the A5H4 area with 5.56 gas port pressure ammo without a can. For similar combinations with the stainless Noveske barrels, I tend to recommend buying them long for their gas system and cut down on the barrel length. That way you can gas it more in the range of an A5H2 without a can, you can easily add more weight for dedicated suppressed that way. Starting off with the A5H4 limits choices.
This is definitely the case. My Noveske Recon and light Recce barrels with LMT E carrier, Vltor A5H4, and green springco spring, cycles and locks back Tula .223. Every time. 1.) Noveske's are over gassed. 2.) I am a big believer in the LMT e-carrier increasing the margin of reliability by reducing the amount of work required to extract the case due to chamber pressures dropping more before extraction which reduces the force of fiction of the case walls on the chamber walls (as you have made clear here and in other threads).
My go-to BCG now for reliability is LMT e-carrier, V7 Weapon Systems Cryogenic treated C158 phosphate bolt, V7WS 4310 melonite cam pin, and mil-spec chromed firing pin.
The slick coatings are cool but phosphate works well. All require lube and are only as good as the company standards that make them just like anything else. I like QPQ treatment and NP3. I'd like to see LMT do a e-carrier in QPQ.
It will be interesting to see what comes of 2A Arms new Cryoed, QPQ 9310 bolts.
Great info. I was not aware that Noveske barrels are typically overgassed. I had always had the impression that the gas ports were on the smaller end of the spectrum, similar to BCM.
I don't mean to beat a dead horse, but the question remains (unless I've just missed the answer): is one method more effective than the other for increasing dwell time? In one corner we have a standard weight LMT E-Carrier with an altered cam path that allows the carrier to physically move farther back before bolt unlocking begins. In the other corner we have carriers that are designed to be slightly heavier than a typical FA M16 carrier, such as the Fathom Arms E-Carrier, which resist acceleration more due to the increased mass, also increasing dwell time. Is either of these methods superior to the other, or do they both accomplish the same net result?
I'm also curious about differences in carrier life between the two aforementioned bolt carriers. On one hand, the QPQ treatment on the Fathom Arms carrier increases surface hardness and reduces friction, which should greatly reduce cam path wear. On the other hand, I would expect the altered cam path of the LMT carrier to reduce wear as well due to less stress on the bolt during unlocking. Will one be more durable than the other, or is this one of these situations where it doesn't really matter anyway because it won't wear enough to matter?
I'd like to see LMT do a e-carrier in QPQ.
^ This. I even inquired at LMT about procuring a batch of partially finished E-carriers (basically all the machine work done, right before hard chrome is applied to the inside of the carrier) about a year ago to send them off for QPQ treatment myself but was shot down cold. :(
Great info. I was not aware that Noveske barrels are typically overgassed. I had always had the impression that the gas ports were on the smaller end of the spectrum, similar to BCM.
I don't mean to beat a dead horse, but the question remains (unless I've just missed the answer): is one method more effective than the other for increasing dwell time? In one corner we have a standard weight LMT E-Carrier with an altered cam path that allows the carrier to physically move farther back before bolt unlocking begins. In the other corner we have carriers that are designed to be slightly heavier than a typical FA M16 carrier, such as the Fathom Arms E-Carrier, which resist acceleration more due to the increased mass, also increasing dwell time. Is either of these methods superior to the other, or do they both accomplish the same net result?
I'm also curious about differences in carrier life between the two aforementioned bolt carriers. On one hand, the QPQ treatment on the Fathom Arms carrier increases surface hardness and reduces friction, which should greatly reduce cam path wear. On the other hand, I would expect the altered cam path of the LMT carrier to reduce wear as well due to less stress on the bolt during unlocking. Will one be more durable than the other, or is this one of these situations where it doesn't really matter anyway because it won't wear enough to matter?
^ This. I even inquired at LMT about procuring a batch of partially finished E-carriers (basically all the machine work done, right before hard chrome is applied to the inside of the carrier) about a year ago to send them off for QPQ treatment myself but was shot down cold. :(
Yes, the A5/rifle action system adds more of a delay in initial unlocking than the LMT enhanced carrier when comparing the two to a properly gassed carbine action H2 system with the conventional carrier. The carbine action spring cannot support the same mass as the rifle action spring while maintaining the balance of function. When adding the LMT enhanced carrier to that system with a carbine action, it may be more durable to the bolt lugs, but the width of the span of operation can be highly reduced. Using the A5 type of system in conjunction with the LMT enhanced carrier can be broadened that to a satisfactory point. The LMT enhanced carrier tends to overspeed in carbine type action systems and runs into issues, as the applied gas becomes more than what is needed fully cycle that action properly, as the required work decreases. I would hesitate to recommend the LMT enhanced carrier in a carbine action application, it may be easier on the bolt lugs, but may have a narrower span of operation, it could be more durable and less reliable. I would NOT hesitate to recommend the A5 or rifle system properly weighted for most any AR platform. It is interesting to note that the combination of them can have very positive results in most any configuration when combined properly balanced.
jerrysimons
08-04-15, 09:59
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^ This. I even inquired at LMT about procuring a batch of partially finished E-carriers (basically all the machine work done, right before hard chrome is applied to the inside of the carrier) about a year ago to send them off for QPQ treatment myself but was shot down cold. :(
I think this would not work since phosphate carriers are machined to a spec which allows for the addition of dimensions when the inside is chrome lined. A nitrocarburized carrier would have to be machined to necessary dimensions since the treatment is not adding material.
In light of what Tom has elaborated I feel I should qualify that my use of the LMT e-carrier is always coupled with the A5 buffer system. The thing actually gives more uumph to the rearward recoil stroke otherwise. I think for a while it was thought to be lightening recoil by bleeding off extra gas perhaps even like the way carrier key regulation works but the thing actually lets you get away with less gas because less force is required to extract the case. Without either extra buffer weight using the A5 buffers or reduced gas at the port, you will likely notice increased felt recoil due to velocity increase as the altered cam pin track lets the carrier travel straight back longer before the cam pin is laterally engaged and when the bolt does unlock and tug on the case, the case is not grabbing back as hard, so the BCG bottoms out faster/harder unless compensated for.
Singlestack Wonder
08-04-15, 14:37
Colt, BCM, Daniel Defense, LMT.....my two cents....
I just bought this for my DDM4V5s from Joe Bob's. http://www.joeboboutfitters.com/Daniel_Defense_CHROME_Complete_Bolt_Carrier_Group_p/dd-04-013-19135-043.htm
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