Rubber City Armory

[Corvette Racer]

Anybody familiar with them?

http://www.rubbercityarmory.com/index.php

 

[Corvette Racer]

Had 50 in stock. Went ahead and pulled the trigger on one. I'll post the results.

 

[whitsend]

Never heard of them before now, but here is a rather in-depth post on m4carbine.net

http://www.m4carbine.net/showthread.php?t=120946

 

[Cadien]

Looks nice. I'll be curious to see reports after someone has run a substantial # of rounds with one. I wonder how different this is from the Failsafe coating. I once saw a test with a dry 1911 that had around 300 rounds fired and when the range test was done, a light tap and a bit of wiping and you couldn't tell it had been fired. Powder just fell off.

 

[JWG223]

I wonder how the 900*F+ temps affect temper of the bolt and cam-pin...

 

[Corvette Racer]

Seeing that it is mil-spec, is made from the right materials (8620/Carpenter 158), is heat treated, shot peened, and MPI tested, I have no issues with. BCGs are going for over $300 on GB, and you don't know if they are new or used, or who the manufacturer is in most cases. I could care less about the coating, it is in stock and is priced right for me. I will lube it as I would any other BCG. BTW - this morning Shade told me he had 500 in stock. Mine ships tomorrow.

Those guys on M4 are A-holes ("I only use Colt or BCM"). If I had only used GM blocks in one of my engines, I would be picking up pieces.

 

[whitsend]

Seeing that it is mil-spec, is made from the right materials (8620/Carpenter 158), is heat treated, shot peened, and MPI tested, I have no issues with. BCGs are going for over $300 on GB, and you don't know if they are new or used, or who the manufacturer is in most cases. I could care less about the coating, it is in stock and is priced right for me. I will lube it as I would any other BCG. BTW - this morning Shade told me he had 500 in stock. Mine ships tomorrow.

Those guys on M4 are A-holes ("I only use Colt or BCM"). If I had only used GM blocks in one of my engines, I would be picking up pieces.

Yeah lots of pricks on M4, but after reading the entire thread and overlooking the pricks, what I got from the thread was what you posted above.
Mil-spec,quality BCG, the coating won't hurt anything and will most likely help with cleaning.
And I agree, still lube.

 

[Corvette Racer]

Some nice pics here, middle of the page:

http://www.ar15.com/forums/t_3_4/595389_Bolt_Carriers.html&page=153

 

[JWG223]

It's not a coating, it's a metal treatment that exceeds 900*F. How does this play with the very specific heat-treating of the Bolt? The cam-pin?

Interestingly, JP QPQ's their carriers, but not their super expensive "enhanced" bolt. Why...?

I did some searching and here is what Bill Alexander has to say on it:

Ok, so in English, will QPQ reduce the impact toughness of a bolt and lead to a shorter round count life or not?

Alloys that create nitrides are typically contain aluminum, chromium, molybdenum and titanium. With this in mind, nitriding works better on metals that contain these metals, but not in excessive amounts as these metals can create very hard and very brittle (especially in the case of aluminum) nitrides that break easily and cause cracks to form. So the real question is at which amounts *will* these nitride creating metals create a situation where the surface loses its impact toughness? There were a lot of "mays" and "mights" in the above post, i'm looking for verifiable data please.

Same question for barrels and barrel extensions.

Also, does not the addition of the nitriding process lower the coefficient of friction between the materials, thusly reducing the stresses between parts? And since hydrogen isn't part of the nitriding process, nor is surface etching, how does your final statment factor into the equation?

In English, you are looking at a very complex system and then asking questions about metallurgy and fatigue analysis. The answer is statistical and dependent upon the bolt alloy, geometry, surface treatment conditions and loading cycles amongst many others. If you want a brief answer I would not use this type of treatment on an AR bolt and you should note that none of the competitors in the recent competitions for the military submitted this. The current TDP precludes the use of CN for bolts specifically for a reason.

I will answer this out of order. You are looking for verifiable data, for a very case specific application. This can only be achieved by an extended series of testing and given the fact that the life is governed by first stage fatigue in a low cycle environment it is not a viable proposition to accelerate the tests. The only recourse is to real time testing to collect the data. In English you need to shoot a minimum of 32 rifles to failure using a certified batch of ammunition. Ideally many more. Your verifiable data costs considerable money. Unless the party concerned is conducting an academic exercise or writing a research paper the existence of the data is of no help as you will have no ability to either access it or duplicate the result.

You have half answered you own question in that you have researched and found that the nitrogen free radicals can work adversely with certain elements. As to the percentages of elements present that will be detrimental to a metal this will depend upon the loading and the geometry as well as the chemistry. Potential micro surface cracks in a 25lb retaining piece that is 8" thick are of little consequence, as an illustration, but such initiation points in a bolt would be detrimental. Bolts are typically, what is generally referred to as surface hardening alloys, in that the carbon content is lower and they are usually used in an application where the surface will be hardened. But they are also higher alloys so in this instance they are not clearly classified.

Barrels, good ones, are CMV through hardening alloys, draw your own conclusions! Dropping the alloy specification can allow a barrel to be effectively CN treated. The manufacturer must determine this. Stainless steel is out and the ability of the nitrogen to combine with the chromium will frequently leave the resulting part more susceptible to corrosion that the virgin part.

Barrel extensions are good if run in isolation. They are a very suitable alloy but must be taken in the as machined form. CN over the existing case hardening is a variable proposition.

To address friction between components, again the information that you are using is case specific example. In this case the tribological results from a controlled standard test. The information should be regarded as indicative of properties that can be achieved. If you can definitively quantify that a CN treated bolt/barrel extension will impose less bending stress on the lugs than a classical case hardened combination, when there is substantial contamination from combustion gasses and also lubricant, either as applied or burnt, then you have the perfect answer.

The comments wrt hydrogen and surface etching were general information and correctly are not pertinent to the direct discussion of CN on alloys. They were related to the consideration of surface treatments by other methods and how problems may occur.

I hope that you realize that I am not being evasive in trying to provide answers it is just that a simple yes or no does not exist. I also hope that you do not think that I am being detrimental to the use of CN. Many parts benefit from this finish but like NiB, Chrome, Nickel and Ionbond it is not a universal fix all. The gun industry has the tendency to "find" a process/lube/finish and then finding a single good application, pounce upon it without any further examination and use it for everything they can throw into the vat. This said I am examining CN QPQ for barrels in one instance and I think that bolt carriers may be another great application. I like NiB for through hardened parts and use both chrome and Ionbond in my products.

http://www.m4carbine.net/archive/index.php/t-106680.html

 

[Corvette Racer]

BCG came in on Wednesday. Still waiting on the upper so I haven't fired it yet. Feeks slicker than deer guts and it doesn't even have any lube on it yet. Some pics:

 

[JWG223]

I purchased one of these. I did so only after about a 30 minute conversation with one of the company technical guru's. He answered ALL of my questions, and did NOT side-step anything or "weasel-word" or anything of the sort. I was very impressed. I also asked if this information could be disclosed. I was told that yes, it could. Here is a summary:


-The bolts are mil-spec hardness. QPQ is a heat-treat in and of itself, and multiple mil-spec phosphate bolts were cut into many pieces and the hardness at various depths was measured. The QPQ process RCA uses causes a RC hardness that EXACTLY mirrors the mil-spec case-hardening method at EVERY POINT AND DEPTH on the bolt. The same was done with the carrier. This is the culmination of 2 years of work. RCA is NOT some company that said "Hey, we can nitride this thing and turn it black! WOOT!"

-Currently, Colt has tested the BCG. They did not have a mechanical failure of it in 5,000+ rounds per RCA's Facebook page (I was told 10,000).

-Another company has tested the BCG to roughly 8500 rounds without failure.

-RCA has run the bolt/carrier for 1,000 rounds, full-auto, suppressed, dry, and will post a video at a later date. No failure of the BCG or weapon.

-To-date, noone has had a mechanical failure of this product. That said, with the cost of ammunition currently, test-data is limited, with many companies testing them having put only 1,000-4,500 rounds through them. There is no miraculous 100K round-count story at present or anything of the sort.

Everything about this BCG, has been thought about. Every tiny single nit-pick heat-treat, dimensional, whatever detail. Right down to the use of the RTV type sealant (It's not RTV, I just don't know the name of it) that so-many companies leave out.

Is it a miracle product? No. RCA also recommended that I lubricate it, as well. It's not billed as "run dry". It will run BETTER DRY than some others, but it is not meant to be some lubeless wonder.

I view this as a product evolution, just as melonite has began surpassing chrome-lining in some manufacturer's barrel production.


*Disclosure: I am a previous customer of H&M, who is the parent of RCA. I had a P226 Elite ST QPQ'ed by them about 4 years back. I spoke with the same person today, as I did then. This is not some "upstart" company who is "learning as they go".

 

[Corvette Racer]

Due to the ammo shortage, I also don't have the opportunity to do a full fledged test, however, I did throw about 100 rounds downrange last week with no FTL/FTF/FTE issues. I lubed as I would any other BCG and operation was flawless. Came out exceptionally clean.

 

[JWG223]

My BCG just showed up. It's literally a work of art.

The good:

All of the surfaces are VERY "clean". The bolt articulated within the carrier much more easily than many of the new phosphate/chrome-lined BCG's I have from companies like Noveske, etc. The finish looks great, and feels "slick", but oil does not "bead" or "run off". You can still run this thing "wet" if that's how you prefer (I do, personally). The staking is text-book and appears very well done via compression and not impact (less chance of shearing a bolt, impact staking causes this, sometimes). I noted what appears to be a bit of "run-off" from the sealant that the TDP calls for to be placed beneath the gas-key. RCA is literally one of the only companies I know that does this. The run-off was inconsequential and did not require removal. Calling it run-off gives it a negative connotation that I don't like, because I don't view it negatively, but I just don't know what else to call it, what I glimpsed when looking under the goose-neck of the gas-key where it presses against the body of the carrier. Total non-issue, and I was glad to see it! Props, RCA!

The neutral:

I would like to see MPI somehow denoted on the bolt, and batch-testing changed to individual testing. I know that batch-testing MPI meets the mil-spec requirement, and that there is much debate that HPT indeed can cause a weakening of the bolt and shortening of its life, up to 25%, without showing in the subsequent MPI test, so I am not so big on HPT, but for $250, I think individual MPI testing would be nice, although I do not know the price impact/current profit margins. I noticed that everything had "ridges" on non-sliding surfaces. I checked the bolt, and it did, as well. I looked at my other bolts from Noveske, and they did not. Keep in mind, I said "non-sliding surfaces". The cam-pin, where the gas-rings ride, etc. do not show this machining characteristic, and I do NOT think it will interfere with anything. On most BCG's, the ridges on the carrier are likely covered by phosphate. I have seen them on the inside of carriers on the tail-end, as well as visible "through" the chrome-lining, and this carrier exhibits less than that. It is very "clean". The bolt, on the other hand, exhibits these machine characteristics moreso than other bolts I have seen, but is perfectly smooth on the tail, bolt-face, and the "ring" that rides in the BCG. Again, considering the longevity testing done by Colt and others on RCA products, I do not feel that this is an issue of durability or wear, but rather a cosmetic observation of no meaningful import. Hence "neutral".

The bad:

The only negative I have to comment upon is the use of a unique extractor spring. It is 4-coil, the bottom coil is not flat-ground on the bottom, and it is accompanied by a plumb-colored O-ring that felt very hard compared to the CRANE O-rings I have. I promptly ditched it for the Colt "Gold" spring which is currently what is spec'ed for all M4/M16 weapons from the MK18 to the A4. I ditched it without even trying it, because I do not run any "unknowns" that I do not have to. I did a lot of talking with H&M about their BCG before I decided to purchase their product, as it is unique, and it has benefits that I appreciate, but I cannot see any benefit what-so-ever from running a unique extractor spring of unknown origin in it, and thus replaced it. You may opt to leave yours in situe, and it may serve you well. I simply removed the unknown and went with a known.

My personal course of action and expectations:

This BCG will be going in my 300 BLK MK18 as soon as Daniel Defense delivers it, and I am purchasing several more for christmas gifts (sadly delayed due to the tragedy in Newtown, and the subsequent lack of BCG's in stock). I will evaluate them in numerous weapons over the course of the next year, and am curious if they become "the new PMAG"---as in---the new standard for performance. I personally expect identical performance to my current BCG's, with the exception of easier cleaning and greater corrosion resistance. I have seen rust on my personal BCG's (and discontinued using the lubricant I was using at the time because of it), and this item just gives me more security. One of the primary failures of the M4 bolt is from fracture at the cam-pin hole, and any stress risers or inclusions (rust) can lead to a shortened life-span. Also, cam-pin wear should be reduced. Cam-pin wear can lead to tolerance stacking and added stress on the cam-pin hole. Further, I think that due to the "slicker" finish that carbon and grit will be less likely to build up on the surface of the bolt-stem, and firing-pin, as well as the carrier portion that the FP passes through. I have not seen a carrier bind in an upper, but I have seen the bolt require so much force to articulate and the FP drag so much on carbon, that this caused an issue. I do NOT think that this BCG should be run dry, but I do think that the surface treatment may allow longer service intervals between lubrication events. I would recommend running it sopping wet, like any other BCG in the M4 family.