@Augee - Here are two later production U.S. Army FNMI M16A2s that I photographed back in March. They exhibit the late style lower forging and use an interesting font - kind of flat and wide in the way it is imprinted into the surface.  I think the majority of the text is engraved, but the serial numbers are stamped.  I'll defer to the experts here on the exact process.

FNMI M16A2 Serial No. 7190302

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FNMI M16A2 Serial No. 7190353

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I can weigh in a little here, those are not late A2’s from FN, they’re actually fairly early. The first A2’s FN produced had the electro markings on them. Best guess is the DOD told them to stop doing that do to them wearing off quite easily. I’ve personally seen electro’d A2’s that had the serial restamped under the original one as it was no longer readable. FN then used a rotary engraver for approx. 100k A2’s before getting a proper rollmark die in the 7.2 million range.

William

William, thanks a lot for the reply about those FN lowers. I remember you contributing a lot of information to my questions about the early style of electro pen markings on FN lowers in this thread. I guess "later style" was a poor choice of words. I really meant "later than the original electro pen markings," because I wasn't sure when this style of engraving came into use. I see now that in that old thread, you referred to the engraving replacing the dot matrix, and then roll marking replacing the engraving. That all makes sense now. Maybe "mid-production FN" would be a better way to categorize it? This type of engraving would be interesting to try to replicate on a clone lower, since it looks like it was done with a small end mill instead of the usual rounded bit that seems to be more common.

I'm still trying to work out a way to replicate the FN dot matrix markings. I'm considering following a stencil with a small punch and very tediously making a series of many, many dots... Then maybe rough it up a little to approximate the electro pen. The real markings have always looked fairly sloppy to me anyway, so it doesn't seem like it would have to be too precise.

3ACR, that is the kind of FN I had in Iraq in 05-06, except mine, oddly enough, matched upper and lower. That is the shiny type PG I keep talking about every so often. I do know that that FN also used a peel washer as well. Mine was even a 7 mil series.

Thanks, that's interesting. I've probably mentioned this somewhere before, but my unit had mostly early FN A2s with the dot matrix style lowers in 05-06. I actually still have copies of the property book that list all of the serial numbers. There seems to have been a few oddball higher serial numbers, like they were issued as replacements or added to the books later. I'll have to dig them up to see if any of them would fall into what I'll now call this "mid-production" serial number range with engraved lettering. I don't recall ever seeing a Colt A2 in that unit, and I don't think I've seen a serial number in the property book that looked like a Colt.

It's been frustrating to see Photobucket's banner and (sometimes) blurring cover up a lot of the great reference photos in this thread and others. I hope the original posters don't mind, but I opened up each Photobucket link in this thread, downloaded the original photos, and uploaded them directly to the forum so they show up without the banners. I really appreciate the original contributions to this knowledge base, and I thought this would make them more useful again. Maybe @Augee can use the URLs for these photos to update the original post with clear images again. I'm reusing the original captions where possible to connect them with the photos.

Non-Colt U.S. Property M16s:

Balimoy:

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FNMI:

Earlier FN lowers are not rollmarked - but have had their markings engraved in a "dot matrix" style with an electro pencil:

M16A2, FT Sill, OK - Image courtesy of schaz42

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Later marks are rollmarked - Image courtesy of schaz42:

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Excellent photos posted by @MauserMatt, with his captions:

Here is the oldest Colt M16A2 I have in my vault right now.

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And here's the "youngest" I have in my inventory at the moment:

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And finally, my oldest FN...

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I can't find the screen name of the member who posted these photos a year or so ago (if I can find it, I'll add the photo credit), but I thought this was an interesting example of a late production FN M16A2. Note the current "M4" style lower receiver forging with the raised "tube" over the rear takedown pin detent/spring channel. It also has a stamped "F" Anchor Harvey upper receiver, which I thought was a forging used for replacement uppers, but it looks like it may have been used for complete late production rifles as well.

FN M16A2 S/N 7451787:

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A late FN M16A2 lower receiver, SN 7319173, along with Colt M16A2 lower receiver, SN 6380008. Both are likely Cerro forgings, with the FN being the later "m4" style. Image originally found on Reddit by member mb44kar.

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Original image link (image above uploaded directly in case this one eventually disappears).

I think the top FN receiver is a Kaiser Alum. forging.  The selector stops tend to be more rectangular on a Cerro.  The bottom receiver is definitely a "Type 3" Colt only forging.  The RE reinforcing has no "corner" at the lower front edge.

Agree on all counts, haven't seen any newer forgings with round enough stops to match that. I'm not sure what the trend (if there is one) is in serial numbers...where the switch happened.

Also of interest is the bluish tint to the FN receiver and the flatter grey of the Colt. The buffer tube and stock also show some differences. I've noticed, in a statistically-insignificant handful of instances, FN buffer tubes tend to be a more stand-out parkerized color. Neat cage-coded hammer too!

In the pic the FN buffer tube is less black/grey and more greenish/yellow like the color of parkerized parts, unlike the Colt. On maybe 3 examples I've seen of FN vs. Colt A2 rifles, this one included, that has persisted. It's likely not indicative of actual differences between FN and Colt, just an observation. Don't mind my ramblings.

Just a different dye lot in the anodizing.  Was getting excited @ the idea of FN steel buffer tubes.  

I'm a little slow in responding, been a bit busy these past few weeks. I see what you all are saying, but I think that FN lower looks identical in detail to the one in my post above it, which has the late style full "tube" for the rear takedown spring. I don't believe that style of tube is found on KA forgings. Both of those FN lowers seem to have the same style of selector stops.

Another thing I noticed, which may not be accurate since this forging in Dex223's photo is still "raw," is that the two FN lowers above seem to have a slightly more gradual curved taper from the front pivot pin hole down to the magwell. I think the shape of the KA forging curves in to the magwell a little sooner, without the longer gradual taper toward the bottom:



It just looks to me like the curve in that area is a little different on the two FN lowers. That may not be accurate, but those two FN lowers, which both appear to be later A2 lowers with rolled / stamped markings instead of the mid-production engraved markings, look like they have identical selector stops to me, and the later number one, 7451787, has the detent spring tube on the right side which I didn't think was found on KA forgings. What do you all make of that lower, 7451787? Is that a Cerro lower, or a later version of one of the earlier forgings? Thanks for the feedback!

@3ACR_Scout

I think the purplish lower you posted is a Cerro, I haven't seen any other company make that style of rear reinforcement. I can't see the difference between the fronts of the magwells, maybe that requires a good comparison pic.

As for the stops, I think they are different but the difference is subtle..In this comparison pic, draw a horizontal line tangent to the curve of the selector stop (the portion which has been milled almost-flat to accommodate the selector). The purplish FN lower you posted actually has a segment in the middle which is horizontal, whereas the other grey FN doesn't seem to. The grey FN's selector stops seem to just be two different radii ellipses meeting at a point in the middle.
But this also might just appear this way because of the picture quality. And looking solely at the fact that they grey lower is rollmarked and the purple lower is engraved, I'd agree that the grey is Cerro. It seems like you'd like to know if the switch from Kaiser to Cerro forging happened at the same time as the switch from engraving/punch markings to proper rollmarks. I'm also interested in this but have no data.




By the way, looking at the Kaiser forging FN lowers you posted before posting that purplish FN lower, those seem to have different selector stops from both of the above examples. Those have smaller radii ellipses, and rather than meeting in the middle or being joined by a horizontal line, they are joined by a skew line.

Actually, the TDP calls for the receiver extension to be anodized, then coated inside and out with dry film lube.  This is a Colt one sold by Specialized Armament.


That's what you're seeing as black/gray or green/yellow.  Whoever made the extensions probably used slightly different formulas of DFL.  That's also what looks like is flaking off of the lower Colt's extension.

@3ACR_Scout
@mb44kar



I don't think either of the FNs are Cerro forgings.  The reinforcing "band" that wraps around the Rec. Ext. area is too narrow.
A Cerro has a wide "band", like this:  (photo from the internet)

The only forging that comes close is a Cardinal, like this:

It has a full tube, but not as pronounced as on a Cerro.  And, it looks to have the more rectangular selector stops.  But, I'm not sure I'd say for sure it's this one either.

As for the fronts of the mag wells, I think that's more of a lighting/angle of photo thing.

Since both are late, high serial number rifles, it would make since that they wouldn't be Kaiser forgings.  But, the Kaiser ones were around at least through the late 90s.  Without any more info on when and which forgings started being produced, I just don't know.

I agree on the continued ambiguity, and I was mistakenly using "Cerro lower" to stand in for the Cardinal you posted - the two were the same in my head for being so similar. But I see the band difference now, and had known the detent tube being partially buried in the band on the Cardinals, just forgot or didn't see here. Thanks

Just curious about the differences between the Colt A2 markings (Pegasus + Colt version vs. Gov't Property version)... Is one older than the other?

I'm curious about the markings on the M16A2 'Gov Property' variety... Did Colt ever transition the markings on the trigger pocket to "Colt's Mfg. Co. Inc." as in the picture below? When did this change occur?

Best guess is mid 1994 as all Colt M4A1s (type classified and adopted by the Army in 1994) including a 3 digit M4A1 have that rollmark.

@3ACR_scout

Here's early 90s colt I saw today.
Sorry about the clp smudged on magwell.
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That's a very nice rebuild of an A1.  Someone at Anniston took great care to do a quality job!

@Augee

This is amazing info! Is there any chance you still have the original pics from the first post you can update the post with please? Many are gone now unfortunately and this is important to preserve. If not and anyone else saved them and can repost them, that would be great too.

I just asked the exact same question pretty much here so will point to this sticky.

https://www.ar15.com/forums/ar-15/-/123-766491/

It seems most of cerro 80%s people have now look like this. What variant are they and what clones are they good for?

https://www.righttobear.com/cerro-forge-raw-80-percent-lower-receiver-p/80raw-1.htm

Current production M4A1s and M16A4s. I may have a photo of a Colt M4 with one of those forgings - they being produced from 1994 on ....

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What would a replacement M231 lower receiver look like?  

If you could dig that pic of the colt out that would be awesome! Thanks for sharing the FNH pic!

Hey everyone, I'm revisiting this thread and the points about the Kaiser vs. Cardinal lower forgings on later FN A2s. I'm going to assume that I was off about Cerro being involved in this discussion at all, and focus on the other two companies. The bottom line is that I think I can replicate a Kaiser lower for cloning purposes but don't have access to the correct style of Cardinal forging. My basic question is whether intermediate or late production FN A2s existed that had roll marked markings, which can be replicated more easily with engraving, vs. the early electro pen / dot matrix style FN lettering. I'd like to do a later FN A2 clone with engraving.

Mid-production FN A2s have this odd flat-bottom font that I posted above, like they were done with a small end mill or a blocky stamp / roll mark process. This style of lettering would be difficult to replicate, so I'm going to skip this group of FN A2s. These are clearly done on a Kaiser lower forging:

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As I posted above, this is what I consider a "late" FN A2. Based on the previous discussion, it uses a Cardinal lower forging with the exposed rear takedown pin/spring tube (slightly different from later Cerro lowers). It has what I consider the "normal" style of roll marked lettering:

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Has anyone seen photos of this style of lettering on a Kaiser lower forging, confirmed by a photo like the one above that shows the FN marking on the upper receiver?  The lower I posted above shows an earlier serial number, 7319173, compared to the one above, 7451787, but I think it's still undetermined whether it's a Kaiser or Cardinal forging, since the rear reinforcing collar look so similar on the two forgings:

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It seems conceivable that FN changed to the "normal" roll marked letter while still using Kaiser forgings, but I'd love to confirm that with photo evidence so I can clone a later FN A2 with engraved lettering. Thanks!

I think you could replicate the lettering of the mid-production lower with stencils and acid etching.  You can vary the width and depth of the lettering by the amount of time the stencil is exposed to the "acid".  I did a little bit of that unintentionally on my M16A4 clone. (left the power on too long)

Also, I would not be surprised if there were "transitional" rifles with Kaiser forgings and modern lettering.  Companies like to use up old inventory before buying new parts.

Some info I came across, wish I had all of it....

That's from the book "The Black Rifle II".

@backbencher
The prototypes had a hammer pin hole, unused, as they were modified M16 receivers. Production unit have the left hand selector stop milled off, and notch on top of the receiver for the selector stop plate. The bolt catch pin is in the same location as the full auto third hole, but the size is different. Production M231 receivers do not have hammer pin hole, as there is no hammer. Colt's address is on the RH side of the receiver instead of the left side, because it's covered by the selector stop plate on the left.

ETA I have the rollmarks to repro M231 lowers, but now the Nodak forgings are MIA.