Opinion: Cam pins

[Joelski]

Rounded, or domed ones specifically. Do you use them? Have you tried them? Got an opinion; post it here.

The thought of upgrading to them has crossed my mind, but I'm wondering if there's a benefit beyond the perception that it reduces friction in the pathway. I swore I wouldn't get this far into tinkering, but the thought intrigues me. What are your experiences with them? I haven't been able to find much using search, so I'm wondering if it bombed or is ineffectual in reality.

The two parts I've been looking at in particular are the Lantac UAR and the POF, cam pin.

I get that parts are consumable thanks to wear and tear, but is there any kind of performance improvement in addition to reduced friction? Is it part of a bigger set of improvements like the UAR that gets the benefits going? What? If you have an opinion on this dump it in here. Thanks in advance for the education on this subject.

[JGifford]

The cam pin interfaces with the sides of the upper, keeping the bolt aligned with the RE. I like the flat larger bearing surface of a slightly beveled or square cam pin.

[alamo5000]

I can't remember where I read it but on some page on the internet somewhere some dude that I never heard of said they aren't as effective as advertised. He went on to say that his guns ran fine with either or leading him to think that it didn't make a difference.

That's all I know [:D] (how's that for third hand information!)

I've never tried it myself.

[Stone]

Your asking the wrong question. You should be asking if anyone has ever broken a standard cam pin under a heavy firing schedule. I run NIB coated pins and havent broken one yet. If it aint broke dont fix it. Besides if it was the magic sauce it claims to be manufacturers would be using them. With the POF you have to use their gas key as well and then re-stake it.

[Joelski]

The bolt does break there, so would something different impact the stress on that hole?

[JGifford]

The bolt does break there, so would something different impact the stress on that hole?

Well, how does stress get there? The cam-pin must transmit it, or the cam pin must not. Binary. If the cam pin does not, then the cam-pin shape doesn't matter. If the cam-pin does, then it does so via interaction with another component, and if it's cracking heat treated steel, and we know the only other thing it's touching is aluminum, then I'd really rather not reduce its surface area of contact with the aluminum, because physics.

[JGifford]

The two biggest reducers of friction I have found are the JP enhanced gas-ring, and a quality QPQ BCG/cam-pin of mil-spec dimensions. These two things considerably slicken the process.

[SINNER]

One of the few areas on an AR that actually "break in" is the cam pin track in the upper. For that reason I go to all lengths to keep the cam pin I used initially in that weapon. On the few weapons I started off with different style cam pins I've noticed 0 change from a Milspec one. Except for a POF cam pin in a .308 that failed in less than 500 rounds.

[schambers]

I've run lantac BCGs for a few thousand rounds. Never seen a perceptible difference between the Lantac domed cam pin and milspec in feel or in wear

[velocity2006]

The Lantac domed style does not wear the cam pin track like a standard milspec pin. The pin itself starts to show wear around 3500 but no wear in the track on the upper that bolt lives in.

[UWone77]

The only aftermarket cam pins I've used is the POF. They were swapped out on a piston upper, when there was a lot of cam pin wear on the inside of the upper. Swapping out to the POF solved this issue. Other than that, I just use the cam pin that comes with the BCG.

[Slippers]

Is this really something to obsess about? Colt cam pins are $7.99 at brownells and bcm sells theirs for $4.95.

[mustangfreek]

Swapped out a can pin once in a certain bcg as it was guoging upper pretty bad and having some issues , to a NIB one ( don't remember brand) had some issues and upon inspection measuring they were bigger, thru back in a new std colt pin or something of the like and no problems since.

Other then that always ran the one that came with the bcg, never ran a nitride one I'm just talking std stuff..

[SINNER]

Rubber City had a huge run of out of spec cam pins. I had one lock up a Vltor upper. Funny part is they tried to deny it for weeks.

[Joelski]

Is this really something to obsess about? Colt cam pins are $7.99 at brownells and bcm sells theirs for $4.95.

It's just discussion. I wanted to learn more about the pros and cons, couldn't find anything really enlightening, so I asked. Even impatience is an opinion, so thanks for that.

[Joelski]

Swapped out a can pin once in a certain bcg as it was guoging upper pretty bad and having some issues , to a NIB one ( don't remember brand) had some issues and upon inspection measuring they were bigger, thru back in a new std colt pin or something of the like and no problems since.

Other then that always ran the one that came with the bcg, never ran a nitride one I'm just talking std stuff..

I don't have any NIB stuff, mainly because there's still so much mixed sentiment. Phosphate and Nitride has been good enough for me and it looks like it'll stay that way.

Again, thanks for the input, everybody. There's a gap between what's written down and real experience that's too big for google to jump sometimes.

[alamo5000]

I think for my opinion after thinking on it for a while... you need to consider this:

Is your upper exactly the correct dimensions inside?

Is the cam pin milled exactly to perfect specs?

While the variances there might be small, but there are still variances. That compounds itself from one manufacturer to another.

That alone makes perceptible problems and perceptible solutions all over the map. I still don't think it's that big of a deal and if there is really a problem there is probably something more serious going on.

[Joelski]

Alamo, the issue of tolerance stacking is present, but expectedly more common and with larger variables in lesser quality brands. Everybody has preferences and there are a few that everybody agrees to stay away from. I think in the case of trying to get a finnicky system to work better a round peg in a linear track might help, but I am not going to get myself into that jam (Hopefully) by sticking to upper shelf stuff.

Of course then there's Colt and their own special mess of tolerance variables they call a TDP... [:D]

[alamo5000]

Of course then there's Colt and their own special mess of tolerance variables they call a TDP... [:D]

Everybody talks about Colt as if they are the AK47's of AR's [:D]

I have never even shot one so I have no opinion of it either way. LOL

[gatordev]

Everybody talks about Colt as if they are the AK47's of AR's [:D]

I have never even shot one so I have no opinion of it either way. LOL

The value of the Colt standard has been lost nowadays since there's a CNC machine on every corner. Historically, Colt was the standard (via the TDP) AND had the means to meet the standard. This is why a Colt M16 (or select-fire AR-15) commands a price premium now. Back when they were being made, the handful of other manufacturers making machine guns didn't have the manufacturing process coupled with the TDP standards.

Nowadays, it's less of an issue because it's much easier to both measure the standard and then replicate the standard on a modern-day machine. The problem is a lot of the Colt fan boys now don't even understand why they pray at the altar of the pony, and that altar isn't as important now with all of the other options available.

[Joelski]

Everybody talks about Colt as if they are the AK47's of AR's [:D]

I have never even shot one so I have no opinion of it either way. LOL

Alamo, I bought my first AR-15 in 1984 and back then, there weren't many choices for accessories and add-on parts, mostly because the internet didn't exist for a lot of us back then and so we had what the LGS carried.

[UWone77]

Everybody talks about Colt as if they are the AK47's of AR's [:D]

I have never even shot one so I have no opinion of it either way. LOL

As if you could tell the difference when shooting it.

No one else builds to the TDP. That's why Colt's are boringly reliable.

[BoilerUp]

As if you could tell the difference when shooting it.

No one else builds to the TDP. That's why Colt's are boringly reliable.

Doesn't FN? They've won some sizeable contracts. Either way, you are talking about competing to be the lowest bidder on a 20+ year old spec (How old is the current TDP for an M4, anyway? Mid-90's is when the Army started switched over from th M16A2 to the M4, IIRC. I got out in 99 and never carried an M4 as my unit (1AD) was, I believe, the last in the regular Army to switch over.)

"boringly reliable" sums it up well. I wish they were a pro 2A company, though. Then I might actually buy their stuff. Instead, I'd prefer to support companies that are both clearly taking a pro 2A stand and also spending money innovating new products. That's why my last major purchase was on a Sig (MPX).

[JGifford]

The value of the Colt standard has been lost nowadays since there's a CNC machine on every corner. Historically, Colt was the standard (via the TDP) AND had the means to meet the standard. This is why a Colt M16 (or select-fire AR-15) commands a price premium now. Back when they were being made, the handful of other manufacturers making machine guns didn't have the manufacturing process coupled with the TDP standards.

Nowadays, it's less of an issue because it's much easier to both measure the standard and then replicate the standard on a modern-day machine. The problem is a lot of the Colt fan boys now don't even understand why they pray at the altar of the pony, and that altar isn't as important now with all of the other options available.
They also don't understand that even back then, the Mini-14 was probably more reliable than the Colt AR15. I know a guy responsible for hundreds of AR15's over his LE career many decades ago, and he is just NOW getting back into AR's, because of how finicky and poorly they performed back when it was just Colt and a few "Copies" in the game.

[JGifford]

Doesn't FN? They've won some sizeable contracts. Either way, you are talking about competing to be the lowest bidder on a 20+ year old spec (How old is the current TDP for an M4, anyway? Mid-90's is when the Army started switched over from th M16A2 to the M4, IIRC. I got out in 99 and never carried an M4 as my unit (1AD) was, I believe, the last in the regular Army to switch over.)

"boringly reliable" sums it up well. I wish they were a pro 2A company, though. Then I might actually buy their stuff. Instead, I'd prefer to support companies that are both clearly taking a pro 2A stand and also spending money innovating new products. That's why my last major purchase was on a Sig (MPX).
The TDP belongs to Colt. Colt is the only one who can use it commercially, as I understand. When the military awards a contract to someone like SDI (gone), or FN, they get a copy of the TDP, but CANNOT use it to manufacture civilian goods, as that would be stealing IP from Colt. Just how I understand it.

[UWone77]

Doesn't FN? They've won some sizeable contracts. Either way, you are talking about competing to be the lowest bidder on a 20+ year old spec (How old is the current TDP for an M4, anyway? Mid-90's is when the Army started switched over from th M16A2 to the M4, IIRC. I got out in 99 and never carried an M4 as my unit (1AD) was, I believe, the last in the regular Army to switch over.)

"boringly reliable" sums it up well. I wish they were a pro 2A company, though. Then I might actually buy their stuff. Instead, I'd prefer to support companies that are both clearly taking a pro 2A stand and also spending money innovating new products. That's why my last major purchase was on a Sig (MPX).

Funny you mention it's a 20 year old, lowest bidder spec...one that many fail to meet even now.

[alamo5000]

The value of the Colt standard has been lost nowadays since there's a CNC machine on every corner. Historically, Colt was the standard (via the TDP) AND had the means to meet the standard. This is why a Colt M16 (or select-fire AR-15) commands a price premium now. Back when they were being made, the handful of other manufacturers making machine guns didn't have the manufacturing process coupled with the TDP standards.

Nowadays, it's less of an issue because it's much easier to both measure the standard and then replicate the standard on a modern-day machine. The problem is a lot of the Colt fan boys now don't even understand why they pray at the altar of the pony, and that altar isn't as important now with all of the other options available.

I am guessing TDP is 'mil spec'? Either way that is extremely interesting information. Thanks for sharing. While obviously I am interested in firearms, but I am increasingly getting more interested in the history of it all.


Alamo, I bought my first AR-15 in 1984 and back then, there weren't many choices for accessories and add-on parts, mostly because the internet didn't exist for a lot of us back then and so we had what the LGS carried.

The internet didn't exist for anyone back in 1984! LOL

In 1984 I was still watching cartoons on Saturday mornings LOL!


As if you could tell the difference when shooting it.

No one else builds to the TDP. That's why Colt's are boringly reliable.

I think now (at least from what I see) you have a whole crap ton of manufacturers that all try to specialize in one specific component or a series of specific components.

My take on it now (and I am up for being corrected) is that companies like CMC make triggers. Companies like Battle Arms Development started out making selector switches and then branched out into other products. A lot of the companies like that though when they get into 'other products' have 3rd parties make their stuff to whatever specs they are given.

But now, how many companies make a full rifle tip to tail in house including all of the components? Probably not very many. It seems like the move is towards design and not as much on in house manufacturing except where specialization exists. Outsourcing seems to be the name of the game now.

[Joelski]

I am guessing TDP is 'mil spec'? Either way that is extremely interesting information. Thanks for sharing. While obviously I am interested in firearms, but I am increasingly getting more interested in the history of it all..

The vaunted TDP is more than a sheet of specs, it's the compendium of knowledge gained and lessons learned between Colt and the military throughout the history of the weapon. It's where spec adjustments (A-2 to A-4), and child branches (AR, CAR, M-4, etc.) are derived. Obviously, the exciting stuff is the latest data.

Think of it as the M16's family tree, and every time the military examines a new spec., it stands in the shade of a grand old Oak.

[gatordev]

I am guessing TDP is 'mil spec'? Either way that is extremely interesting information. Thanks for sharing. While obviously I am interested in firearms, but I am increasingly getting more interested in the history of it all.



To add on to Joelski's post... "Mil Spec" gets thrown around entirely too much by people who don't understand what that means. At work, we have what is essentially a Swiffer dust mop thingy, however it's built to a military specification. That doesn't mean it's chrome-lined or has had MPC testing, it just means that it was procured to meet a very specific design spec. In this case, it's to clean some VERY expensive mirrors.

Mil Spec can mean anything. The actual specifications are part of some sort of data package and are a result of specific requirements brought to a contractor for them to design and build to. At the end of the day, the USG owns the package and can always take that information to another contractor and continue procure the product from another source (after lengthy contract negotiations, of course).

[Joelski]

^^^^

This, plus the fact the majority of people who throw around the term "Mil-Spec", really mean to say "We took measurements and reverse-engineered the Colt piece, plus or minus." Thus, the origin of tolerance stacking.

Another important facet of tolerance is end-play, or "slop". I have two really high quality, expensive components that barely fit together, let alone reciprocate properly because interpretation of dimensions and tolerances isn't the same as known, good measurements backed up by gazillions of pallets of rounds.

Along with FN, I'd venture that LMT has also been trusted at some point to peek at the TDP.

[JGifford]

^^^^

This, plus the fact the majority of people who throw around the term "Mil-Spec", really mean to say "We took measurements and reverse-engineered the Colt piece, plus or minus." Thus, the origin of tolerance stacking.

Another important facet of tolerance is end-play, or "slop". I have two really high quality, expensive components that barely fit together, let alone reciprocate properly because interpretation of dimensions and tolerances isn't the same as known, good measurements backed up by gazillions of pallets of rounds.

Along with FN, I'd venture that LMT has also been trusted at some point to peek at the TDP.

SDI was, as well, and actually built some contract guns. That said, they are no more.

[alamo5000]

To add on to Joelski's post... "Mil Spec" gets thrown around entirely too much by people who don't understand what that means. At work, we have what is essentially a Swiffer dust mop thingy, however it's built to a military specification. That doesn't mean it's chrome-lined or has had MPC testing, it just means that it was procured to meet a very specific design spec. In this case, it's to clean some VERY expensive mirrors.

Mil Spec can mean anything. The actual specifications are part of some sort of data package and are a result of specific requirements brought to a contractor for them to design and build to. At the end of the day, the USG owns the package and can always take that information to another contractor and continue procure the product from another source (after lengthy contract negotiations, of course).


^^^^

This, plus the fact the majority of people who throw around the term "Mil-Spec", really mean to say "We took measurements and reverse-engineered the Colt piece, plus or minus." Thus, the origin of tolerance stacking.

Another important facet of tolerance is end-play, or "slop". I have two really high quality, expensive components that barely fit together, let alone reciprocate properly because interpretation of dimensions and tolerances isn't the same as known, good measurements backed up by gazillions of pallets of rounds.

Along with FN, I'd venture that LMT has also been trusted at some point to peek at the TDP.


Now we are starting to get interesting! :)

A "mil spec" component might not be the same thing as a 'mil spec package'.

Just from my rudimentary gunsmithing knowledge it seems to me that parts that are made to function together tend to function better together.

That is kind of what I was getting at earlier in stating that it seems to me that a lot of the industry people now are specializing in one part here or one part there which in and of itself has a lot of benefits because they can make new products out of new materials that can be superior.

For example the new Nitride carriers with the bolts made out of something other than carpenter steel (like my Griffin one) which is made out of AISI 9310. I am far from an expert in metals and all that but what if that stuff turns out to be way the hell better than carpenter steel but costs 25% less to make? Wouldn't that be an improvement?

That said having a firearm that is hand fitted can eliminate a whole lot of variables and eliminate a lot of slop. Even things like drilling port holes on barrels... a port hole that big with a barrel that long combined with this buffer weight and that spring.... how many of us have gone through that or some variation of it?

[gatordev]

For example the new Nitride carriers with the bolts made out of something other than carpenter steel (like my Griffin one) which is made out of AISI 9310. I am far from an expert in metals and all that but what if that stuff turns out to be way the hell better than carpenter steel but costs 25% less to make? Wouldn't that be an improvement?


But none of that has anything to do with Mil Spec. Something may be made with better or worse materials, function better, and even be cheaper, but if it's not made to the specification set my the military (in this case), then it's not Mil Spec. Mil Spec doesn't specify better or worse, it just is what it is, a specification.

That said, it is possible that something that improves function (or at the very least, is thought to improve function) but isn't in the spec can then be incorporated into the spec. This happens all the time across the DoD. A simple, gun-related example it the inclusion of the extractor ring and spring.

[HWS]

But none of that has anything to do with Mil Spec. Something may be made with better or worse materials, function better, and even be cheaper, but if it's not made to the specification set my the military (in this case), then it's not Mil Spec. Mil Spec doesn't specify better or worse, it just is what it is, a specification.

That said, it is possible that something that improves function (or at the very least, is thought to improve function) but isn't in the spec can then be incorporated into the spec. This happens all the time across the DoD. A simple, gun-related example it the inclusion of the extractor ring and spring.

Assuming the underlying metal of the cam pin is mil spec, is what is the evidence or experience of anyone here regarding the chrome/boron coating being superior? Also, BCM has a good reputation for BCG. Is their cam pin a solid choice? Prices vary so much. Normally that is an indication of quality but I really don't know in this case.

[FortTom]

Every AR I own performs flawlessy. I do experiment, but I usually go back to where I came from, as far as metullergy and quality of parts. I haven't had a jam, mis fire, hang fire or any thing else in years, with the exception of some .300 Weatherby mag., in for everr. Nowday's AR parts are pretty much as good as they get. I've experiment with different cams also. Stock works fine.

FT;)

[HWS]

One of the few areas on an AR that actually "break in" is the cam pin track in the upper. For that reason I go to all lengths to keep the cam pin I used initially in that weapon. On the few weapons I started off with different style cam pins I've noticed 0 change from a Milspec one. Except for a POF cam pin in a .308 that failed in less than 500 rounds.

So you are saying keep the pin until it fails or degenerates badly, right? This idea of breaking in the cam pin track is new to me. Any additional information?

[mustangfreek]

So you are saying keep the pin until it fails or degenerates badly, right? This idea of breaking in the cam pin track is new to me. Any additional information?

Just shoot it...lol

He saying don’t swap crap around and pay attention to what it’s telling ya.. where the wear is happening..idk..that’s my take on it