LMT Enhanced carrier again - where to get Cam Pin ?

[dallas]

I purchased LMT Enchanced carrier some time ago for 5.56 but now decided to go for 300 Blk rifle. During some reading on forums I found some information about modified Cam Pin for LMT Enhanced carrier, but I never got this cam pin with carrier from LMT (I ordered carrier only, no bolt).

Where to get this Cam Pin now? There are some notices about LWRC Enhanced Cam Pin but this is not listed at LWRC website for present moment, looks like discontinued. Any replacement? Please advice.

[Dr.Phil]

Dallas,

I'm the one who wrote the post you are referring to.
There is no LMT Enhanced Cam Pin.
The LMT Enhanced Bolt Carrier Group uses a standard MILSPEC Cam Pin.

I switched to the LWRC Enhanced Cam Pin because I noticed gouging on the Cam Pin that came with my LMT eBCG.
The LWRC Enhanced Cam Pin is nickel plated, had an anti gouging notch on one corner, and is marked so that the Cam Pin is oriented the same way every time it is installed.
Last time I checked, the Enhanced Cam Pin is no longer listed on the LWRC web site.
You may want to give them a call to see if it is still available.
It is possible that they still make them, but stopped listing them for individual purchase.

I have been using the LWRC Enhanced Cam Pins in my uppers for several years now and have noticed that they do hold up much better.
Going without the Enhanced Pin is not a game changer, but in my case, I wanted to have the best BCG setup that I possibly could.
The only changes that I could think of to make that could improve the LMT Enhanced Bolt Carrier Group was, the LWRC Cam Pin, switching to a McFarland one piece gas ring and to polish the bearing surfaces of the Bolt Carrier.

I'm sure you will be happy with your decision to run the LMT Enhanced Bolt Carrier Group.
It is an amazing improvement to the age old Direct Gas Impingement System.
(The improvement to reliability and accuracy is worth the price of admission.)
Best of luck to you getting a Cam Pin from LWRC.
(Edited to add: I just found out that the LWCR Standard Cam Pin has the same Nickel Coating as their Enhanced Cam Pin. https://www.lwrci.com/p-303-standard-cam-pin.aspx)

If you get in a pinch and just have to have one, I may have a spare in my armorer's tool kit.
Alternately, you could always look at the POF Roller Cam Pin Upgrade.

http://www.pof-usa.com/shop/index.php?i ... er=product

Cheers,

Phil

[dallas]

Phil,

thank you so much for this detailed reply! Everything is clear now.
I slightly worried about Cam Pin shape and dimensions after some reading.

What do you think about this turned Cam Pin from 17-4 Stainless Steel and hardened?
I recently found these on ebay http://www.ebay.com/itm/330881206130
I think they should be very durable and smooth.

It might be good idea to get this one instead of just nickel plated?
Not a problem to take both and compare but I also looking for the best parts for my build.

Regards!

[Dr.Phil]

No problem...
I enjoy being able to help.
I had limited assistance early on and like to pass on lessons learned for all to benefit.

I would pass on the stainless steel Cam Pins that you linked to.
The metallurgy of a MILSPEC Pin is very specific for good reason.
If I were in your shoes, I would call LWRC and see if they have any of the enhanced PINs around that they could sell you.
If they did not, then I would either get one of the LWRC Standard Cam Pins or just run with a MILSPEC Cam Pin.
The LWRC Standard Cam pin has their proprietary nickel coating which adds lubricity and durability.
For $10 it is tough to go wrong.
If you wanted to always keep it oriented the same way, just use a center punch and mark one side of the head.

Feel free to hit me up with any additional questions should they arise.

Cheers,

Phil

[drayks]

In the lower picture that DrPhil posted is the Patriot Ordnance Factory ROLLER CAM PIN. I installed that cam pin on (4) different ARs and have been pleased with the results. The roller cam pin is available in a complete kit as pictured, with a notched gas key for ~$45 OR if you have a Dremel grinder and a steady hand you can notch about .015" out of your gas key without disassembly and buy the roller cam pin by itself for ~$25 from Botach Tactical. What I noticed, was that the anodizing was being hit BY MY CONVENTIONAL RECTANGULAR HEADED CAM PIN and exposing aluminum where the cam pin notch started in my upper receiver. If you can see this damage through your ejection port, you have a good candidate for a roller cam pin. Hence, the change to the roller cam pin. Also, it feels smoother in operation when pulling back the charging handle. If you do order the roller cam pin, be aware they also sell one for AR-10s which is larger and obviously won't fit. drayks

[Tom12.7]

When people talk about AR15 cam pin gouging, there are 2 distinct different gouges that are normally referenced.
Upper receiver gouging in the cam pin rotation relief cut is one gouge that is mentioned. It's formed by the corner of the square top of the pin wearing into the surface where it rides during cycling. Depending on the cam pin, it could be minimal and self limiting, all the way to an extreme where it can really chew some metal away.
For example, many of the different "enhanced cam pins" offer more of a radius in that location, plus polished surfaces, coated surfaces, etc. Those can and normally do reduce the gouging in that area compared to the worse offenders.
Some regular cam pins do tend to wear less than others and the gouge seems to self limit at a point, while others do not. Those cam pins are actually totally different design even though they are both considered "mil-spec". Let's take 2 popular cam pin providers that both can be found in "premium" builds. CMT derived cam pins can be found in builds from cheap to higher dollar ones, they are often used in "house" brands of premium builds, they tend to wear uppers. LMT cam pins are found in mid priced to premium guns and the gouge is normally minimal and "self limiting". Looking at each one under magnification, it's no surprise why. I personally pay attention to the firing pin bore details. It's kind've hard to knock the LMT product.
Cam pin coatings can flake and induce wear into other items. I'm not against coatings, but it's hard to beat park that is sacrificial, and hard chrome that when done correctly can serve it's purpose very well.
As far as roller cam pins go, I completely agree that this could be a step forward, as it did show promise 50 years ago, but I have been less than convinced by what I have found so far in this series of platform
There is another gouging that happens in the interface between the camming surface of the bolt carrier and the cam pin itself. Depending on the carrier and cam pin, this also could be from mild to severe. It seems that cam path may have aggressive cut that wears more or less on locking and unlocking. Some say it's a defect, even though some wear is apparent in "perfect" parts. There does seem to be wear that would be considered "normal". A note should be made though that an acceptable cam pathway should wear cam pins progressively less. As in the cam pin wear reduces to the point that it reduces by a margin for each change. An example could be for a M16A2 for 10K rounds for the first, to 15K for the next, etc

[Tom12.7]

There are other factors that I didn't mention that should probably include rotational torque to the action.
With the carbine type action, you should expect more rotational torque than the rifle type/ Vltor A5 action system system. The added delay due to the higher mass and less spring will reduce this action and apply less radial pressure to the cam pin to the upper receiver to reduce the wear.

[Dr.Phil]

There are other factors that I didn't mention that should probably include rotational torque to the action.
With the carbine type action, you should expect more rotational torque than the rifle type/ Vltor A5 action system system. The added delay due to the higher mass and less spring will reduce this action and apply less radial pressure to the cam pin to the upper receiver to reduce the wear.

Just to add some clarification...
The main reason that I initially upgraded my LMT eBCG cam pins was because of the pin itself getting gouged.
I suspected that this was due to the LMT Enhanced Bolt Carrier's modified cam pin track, which is more aggressive toward the end of its travel.
(For those that are not familiar, this modified cam path allows for the bolt to unlock later in the cycle.)

A traditional MILSPEC Bolt Carrier, has a relatively consistent radius on the cam path.

[rimshaker]

Just for reference, here is the AAC cam path. Basically I see a perfect bean shape, with mostly rounded edges and curvatures the whole way. And the noticeable dip in the locked position.

[Tom12.7]

The standard LMT cam pins can wear more than others in their enhanced carrier in the cam path area. If everything is right, that wear becomes self limiting. If something is off, it may take a few cam pins over many thousands of rounds to reduce the issue. That scenario really isn't different than what can happen in most any BCG's.
As far as modified cam pathways in bolt carriers, they're altered for many different objectives. What they end up with, depends on if they are satisfied enough with what those objectives are. I've mapped out the cam tracks in many bolt carriers, as far as displacement, rotation, venting, etc, including the LMT enhanced, the AAC and others. Everyone of them seems to have different pro's and con's with each intent. Some users could see different advantages depending on what their desired outcome could be, same with possible disadvantages. In the confines of the popular AR 15 type platform, with the many possibilities of caliber choices, barrel lengths, action systems, etc, I don't think we've found a standard that would be best overall in my opinion. I firmly believe that the regular M16 carrier, the LMT enhanced carrier, and the AAC carrier all have merit in the different ways in which they can operate and interact as a whole functioning system.