I am starting a dicussion topic on the origins of the "Picatinny Rail", particularly the "Flat Top Upper Rreceiver".
This is intended to be an opportunity to collect the memories of the many people who knowingly, or unknowningly, contributed to what we all now lable as the "Picatinny Rail".
I think this is important from a historical perspective, as the armed services have not only fielded Carbines with this upper receiver, but now the M16A4 Rifle (Marines have ordered a whole bunch).  These development's may tend to prolong the servive life of Mr. Stoner's (1922-1997) design for many years to come, and writters are already writting their new "final chapters" of the Black Rifle.  I would just like for them to get it right for once.
I want to include questions like;
Who is Mr. Weaver, and is not what we have today a logical evolution of his designs?
Did Rock Island Arsenal attach Weaver Rails to AR-10's in the 1970's in an attempt to develop a 7.62 semi-auto sniper rifle to replace the Army's ailing M21 system?
Did the USMC's M16A1 "PIP" program that led to the M16A2, and that was executed at Picatinny Arsenal, ever cut the handle off an M16A1 and attach a Weaver Rail to it and then mount scopes, etc., and use this at several briefings foe several years?
Did the Canadian Liaison Officer see this, and report it to their then ongoing rifle replacement program and subsequently field a very, very, similar upper receiver?
What  other individuals were part of this early flat top upper evolution (proir to 1985)?
Did user's from Ft. Benning, GA see the Weaver rail on Picatinny's modified M16A1 receiver, and ultimately refer to it as the "Picatinny Rail" so as not to be confused with the emerging Canadian pattern?
These questions and more to be answered soon with your help and support.
ColdBlue sends from home...

Check out Duncan Longs AR-15 / M-16 Source Book.

Thanks, I have not seen that.  I will look it up.
However, since I think most would agree that the Picatinny Rail in an evolution of the Weaver Base & Ring design, I'd like to start there.
When I was a kid a long time ago, I remember Weaver Bases and Rings, how far back do they go?
And, when did Mr. Weaver first offer a base long enough to cover, or partially cover, the top of an AR that had had its carrying handle cut off?
ColdBlue sends from home...

Quoted: Thanks, I have not seen that.  I will look it up. However, since I think most would agree that the Picatinny Rail in an evolution of the Weaver Base & Ring design, I'd like to start there. When I was a kid a long time ago, I remember Weaver Bases and Rings, how far back do they go? And, when did Mr. Weaver first offer a base long enough to cover, or partially cover, the top of an AR that had had its carrying handle cut off? ColdBlue sends from home...

Found this on Biggerhammer.net

The history of the Picatinny rail is as follows:

It was not invented by Dick Swan, he was instrumental in the development of STANAG, which is NOT M1913/Picatinny! The stanag is a bolt on precision machines square interface. STANAG stands for
“Standardization agreement” which was a NATO standardization pact from the 80’s.

The M1913 was invented by Earl Reddick of RAD (Reddick Arms Development)
It is a “standardized” Weaver pattern (endview).
What this means is that it is made to a tighter tolerance than the extruded Aluminum rail used in the Weaver product.

The cross slotting of the M1913 is also very precise, both the location of the slots and the width of the slot unlike the haphazard cross slots of the Weaver. The earliest published spec for the 1913 I have seen was dated Feb. 1988

RAD rings and bases were used on the prototype M24 SWS By Remington. RAD was not interested in Mass production of the rings/rails so Remington went to Leupold as they made rings and were suppling the scope for the M24. Technically the M24 rail is not M1913 spec, wrong slot pattern.

Some M1913 products have a recoil shoulder that fights snuggly into the slot of the Rail, most do not.
There is only one item I know of that has the wider shoulder spec and that is the M86 (Aimpoint) QD mount. All “Picatinny” spec rings that are made today have a narrow shoulder, to the best of my knowledge!
Except one, Badger Ordnance makes a ring for the Marine Corps that has a wide lug.

I know that a recent article in a popular gun magazine ran an article making the Swan/Picatinny claim, the above information is correct.

Long says the AR-10 flat top trials occurred at Rock Island Arsenal in 1977.

Let's not forget that the US Army retrofitted all of their SAWs with a rail as well - I assume the specs are the same. What other weapons now use this rail?

Long's book is obviously important, as most people don't know about the Rock Island effort in the 70's.
I found a rack of these flat top AR-10's in Picatinny Arsenal in 1980 when I was assigned there to develop an improved M16 Service Rifle for the Marine Corps.  The M16A2 came out of that 3 year effort.  I was a USMC Major at the time MOS 0302/2102, or Infanty and Ordnance Officer).
When I brough one of the flat top AR-10's back to the office (Joint Service Small Arms Program (JSSAP) office, my "boss" there, Mr. James Ackely knew all about it.  He had been onre of the engineer's on the program.
It was not too long after thet, that my civilian counterpart (Mr. Vince DeSeina) and I0 similiarly modified a M16A1 upper receiver.
More on that later.
ColdBlue sends...

Coldblue
This maybe a very stupid question but how could you be a 0302 and 2102 since they are both primary MOSs and one is a CWO/LDO only MOS and one of a full duty officer only MOS?  Or was that MOS awarded back before the Marine Corps had a acquisition type MOS?

Infantry 0302 was my primary.
After Viet Nam, I was sent to Marine Corps Ordnance Officer's School at Quantico.
The 2102 Ordnance Officer I got after 10 weeks became my secondary MOS.  By the way, I had some interesting classmates, D.I. Boyd and Bob Goler (sp?). both world class marksmen.
When I reported back to Camp Pendleton, I was re-assigned from 3rd Marines to Maintenance Company/Small Arms Repair Shop.  There I had the plesure of working under Lt. Gordon Kampen, one of the true great LDO OrdO's of the era.
At that time the 1st Division was returning from the Nam.  We started and finished a re-barrel program of all M16A1's in the division to ensure everyone had the chrone chamber and bore.  Needless to say, I learned a bunch about the 16, way more than I had as a Rifle Platoon Leader in I/3/1 north of Da Nang.
I was there for about a year, then re-assigned to an infantry assignment.  That started a trend in my career where I would go from an infantry tour to a 2102 assignment.
For example, after I commanded C/1/4 in Okinawa in 1975, I took over The Basic School Armory at Quantico in 1976.  At that time the largest operating armory in the Corps.  I had 2,626 M16A1's in that armory plus a whole lot more.  Guess I learned a lot there to, because that's how (3 1/2 years later) I was assigned the M16 Product Improvement Program (PIP).  Left Quantico for Picatinny Arsenal in New Jersey about January 1980.
However, that back-to-back ordnance tour costs me big time later as I never had an FMF tour as a Major.  After I graduated from Command & Staff, all they could do with this 03 LtCol was to let me have my old boss's job at Quantico--Program Manager Infantry Weapons..."Oh please Mr. Bear, don't throw into that briar patch".
So I didn't exactly go kicking and screaming into that assignment!  That's where I retired in 1991.
Thanks for you interest, and thanks for not cutting me any slack, been a while.
Oh, by the way, no acquisition MOS's back then, we just did it.  Not knowing the rules made it easier.  Just ask Gen. Sattler, current CG, 2d MarDiv., he was my logistician during the second half of the A2 program.
Semper Fi Mac,
DAve Lutz/ColdBlue sends...

The reason I was asking I am being told I have too much time in my MOS and is acquisitions is one of my options after this FMF tour, I was looking at small arms acquisitions, but was told since I was an 08 I would end up working something like AFATDS, TLDHS, PTS or LWTH.

"Coach Satler" is an interesting General, happiest one I have ever met, he loves to sit around with the Lts and BS to the point that the BN COs send over the Capts to rescue the Lts.

Dave,

I know darned well that you know the history...  If you would like to share it, I for one would be glad to read it and further honored to put it to HTML and post it on-line....

Too many topics get lost on these forums as I've been comming here for about four years now and a great many solid topics have come and gone only to be repeated again years later!

Regards,
Quarterbore

I may know a peice of the history, basically a "wedge of time" in the 1980's, but certainly not all of it.
The purpose of this discussion is to try and collect some of the missing pieces.
For example, I was very happy that QCMGR (above) very quickly added the parts about Reddick Arms and the Army's M24 SWS.  That's what I think we want to collect here, I mean the whole story, piece by piece, if necessary.
I am familiar with Leupold's Mk 4 Rails & Mounts, but I had no idea of the Reddick connection.  
I think a key element of the Picatinny Rail's evolution here is the "timing of the accessory grooves and the depth of the grooves, as they are very close to the eventual MilStd M1913 (Picatinny Rail).I also want to see Long's book, as I ordered one on-line yesterday.  But I afraid I'm not going to see much there, hopwever, as a very knowledgeable fellow I know simply asked me if Mr. Long ever interviewed me for his book concerning the flat top upper, and I said, no.  His response to this answer was "well he couldn't have the whole story then could he"?
But I've got to wait on that one, as he (Long)may have interviewed Vince DeSenia from Picatinny, or Jack Pritchard from Ft. Benning, or perhaps some others.
Note also, that QCMGR's comments above, about people who claim to be the Picatinny Rail Upper Receiver inventor.  I have seen these same claims in several publications and they irk me, as most writters today will simply print anything someone with a business card gives them.
Hey guys, more about Mr. Weaver...please!
ColdBlue sends...

Thread Update:
I have not yet received the Long Book and I've been waiting over a week.  I hope I'm not ripped-off by the site I ordered the book from.
I will coment on taht as soon as I read it.
If anyone else has a copy, and there are pages with germain information as to Picatinny Rail origins, please fax them to me at work, (772) 569-2955.
ColdBlue looking for input...

Dave, looking forward to seeing what happens here.

The first time I saw flattop "M1913'ish" rails on the C7 was at ARMEX 89 in Ottawa -Diemaco was showing them off looking for buyers.  Whatever we tried in house at LETE got transfered to Diemaco when LETE got de-established.

Dave, you might shoot them an email - but since they are licensed from Colt any changes or R&D, Colt would know too. - just a thought.

Thanks for the info.
I will do that.  In fact, 3 gents from Diemaco will be here this week.
I believe there is a connection between the the rail upper receiver Vince De Siena and I put together at Picatinny in 1982, and the fact I shared an office with the Canadian Army Liaison Officer, Maj. Rick Wilson because we both shared what each other's services were doing wwin their "service rifle replacement programs".  In addition, I have always been curious as to why the final Canadian flat-top upper has the same number and groove timing as the prototype Vince & I built and freely showed around.
By the way, still have one of those original Canadians with the round bottom grooves on my "walk about" A2, the one I have the Elcan on.
ColdBlue Sends on his first gin & tonic on a Saturday eve...

FYI.....

www.duncanlong.com

shop.paladin-press.com/Store/prodinfo.asp?prodid=4270

[email protected]

Dave,

Well have I got some things for you to tell Diemaco...

Where is the Duncan Long book I ordered?
Update: been three weeks since I ordered from internet.
Ordered from "US GUN CONTROL" site usinf CCard.
Sent them an e-mail on Wednesday, referencing order number, etc.
No response as yet.
Anyone else out there with better reponse from this gun book source?
ColdBlue waiting...

I got my copy here:

www.militarybookclub.com/

Have you tried to contact Long at the above e-mail with specific questions regarding the origins of the Picatinny Rail?  

or for Friendly Canucks

www.militarybookclub.ca

Update on "book service" from US GUN CONTROL.
Still no Duncan Long book.  I have sent US GUN Control two e-mails requesting status of my order (referenceing the order number they sent me via their e-mail, and still no response.
I am going to crder the book from another source.
ColdBlue sends...

Be sure you get the updated copy.  I have the older one and I see it has been revised.

Any updates??????

I an not at home so I have no idea if my order has come in yet - guess I will have to wait till near Christmas.

Received the Duncan Long boook (latest revised edition) from Paladin Press yesterday.  Give a a few days to read through it.  Unfortunately there is no index to find "Picatinny".
Already found two big errors,
(1) it reads as if Colt had all the M16A2 ideas that we Marines actually brought to the table for them at the start of the PIP program in 1980.
(2) also wrong, that the Army delayed buying the new A2's in the mid 80's for several years because they were interested in possibly buying the CAW (Close Assault Weapon-big auto shotgun) that was being funded by JSSAP at Picatinny.  This is total BS.
ColdBlue sends...
 

I used to stop by Earl's shop between 92-94 when he built a couple of guns from me.  He could not mass produce his rings and bases because he is a one man outfit. His shop was in back of his house in an oversized garage.  He did not care about who took credit, all he cared about was building the very best rifles, rings, and bases.  He spent most of his time building the M91 sniper rifles for the SEAL teams.  
He did show me some prototype work he did for the Marines back in the 70's that looks alot like the 1913 we have today.

If you guy's realy wanted to get to the bottom of this shouldn'nt you go to the source? The number 1913 (believe it or not has some significance in this doltrum) Try contacting the program managers of the small arms weapon systems.These guy's happen to be in the know.

There are far more people in the know than I am. Yet the answer is simply very close. Seek and you shall find!

Dave why do I feel you know this to be fact.

Once agins something I think you know.


Dave can you fill in more of our gaps please?


-Kevin

Dave,

My Duncan Long book arrived today - Arrgghhh!
I could have done without it.

Live and Learn

Sorry guys!  It was the only book I could find that referenced the Picatinny Rail.

Wow!
1913...never gave this much thought, just thought it was sequential.  Like M16A1 to M16A2 (even though the "first" M16A2's was the links for Mk 19 40mm ammo).
As far as small arms managers, are you refering to someone with initials like S.S., J.U., or J.A.?
My guess on the 1913 is the 19 refers to the mm distance between the two opposing datums on the four 45's.  On the drawing, this is illustrated as .748 +/- .002" (i.e., 19mm), do not confuse this .748 with the major width of .835 accross the "points".  If you make throw lever type rail grabbers, that dimension is really important.
The 13 most likely refers to the number of grooves on the upper receiver rail.
I'll be making a more detailed post here soon as to "origins".
However, I did find out from "talking to small arms program managers in the know", that the term "Picatinny Rail" was coined by folks at Fort Benning in the mid to late 80's to distinguish it from the Canadian Rail, the Colt ACR Rail, and others on the table during that period.
ColdBlue sends...  

QDC no sweat I just found it fairly basic (and as Dave already mentioned some errors)

I already have The Black Rifle and the Great Rifle Controversy - as well as a ton of manuals - and a fair amount of other stuff.  Plus have confered with some great minds on these systems - and most of them told me to ask Dave (COLDBLUE)

-Kevin waiting patiently

Wish I had talked to the guys at RIA before I made my first post. The number 1913 is an ambiguous number. Was made up by the folks who designed the Mil-Std. It has no real significance. And Dave is right on the money, the standardizing began in the 80's with a special optics program Colt was working on that ended up getting shelfed.

Here it comes.  I'll post it about a page at a time.  ColdBlue sending...Part One:
Between 1980 and 1983, I was the Marine Corps Liaison Officer assigned to the Joint Services Small Arms Program (JSSAP) at Picatinny Arsenal.  Picatinny being the Army’s Armament Research and Development Command (ARDEC) at the time.  My primary mission was to develop a product improved (PIP’d) M16 Service Rifle from the then standard M16A1.  I was selected for this project because of a unique combination of Infantry and Small Arms Ordnance Maintenance training and experience.  My civilian partner in this enterprise, within the JSSAP Office, was a government civilian employee and former Soldier, Mr. Vince De Siena.

During this three year period, we developed a number of changes (usually considered to be “improvements”) that were considered for the PIP M16A1, which eventually became the new standard M16A2 Service Rifle.  Most of these are listed in Long’s revised edition on page 51-52.

However, not every idea we developed was actually accepted by the Marine Corps.  Examples of these rejected ideas were an ambidextrous Safety/Selector Switch, a “stepped” barrel behind the front handguard cap for more secure M203 mounting, a thumb-hole type stock, and a rail type upper receiver that would mount a new low power optic as the primary sight.  These rejections were somewhat based on the notion that I “had been assigned to fix the current rifle, not invent a new one”.  As one old Colonel would often say during periodic briefings, “Major Lutz, you were in here just last week convincing us to fund the Army’s/JSSAP’s “Future Rifle Program” that will replace your new M16 in 5 years or so.  Some of your ideas belong there, not in a PIP’d A1, just fix what’s broke”.  Consequently, “equal to or better” became my guidance, vice “new”.   So went the rail idea and several others.  Ironically, this Colonel didn’t connect  the marking of every lower receiver’s starboard side SAFE, SEMI, BURST; to the next page of “improvements” that started with the ambo safety.

Sadly, that “Future Rifle Program” failed, as did its successor, as did the ACR, etc.  Now, 20+ years later—the A2 has been nothing less than the “future rifle” for thousands of Servicemen and women underarms.

In 1980, modifying an AR with a rail  was not a new idea.  I had examined Weaver Rail modified AR-10’s in Picatinny’s small arms bunker early in my three year tour, and I was impressed with the concept and subsequently inspired.  Vince’s and my direct supervisor in the JSSAP Office was Mr. Jim Ackley.  He had been part of the AR-10 Sniper Rifle Program years before (1970’s) at Rock Island/Rodman Laboratory.  He told me these were the most accurate semi’s he had ever fired. I had also just recently examined the then brand new Steyr AUG-1, that had a low power optic mounted inside its carrying handle, and was very impressed with this concept as well.

So Vince and I decided to make a similar combination from an M16A1 upper receiver.  I bought the longest Weaver rail I could find from a local gun store and cut the handle off an upper receiver (mistake, I should have waited an let the machine shop do it).  Vince then took the rail and the upper to Picatinny’s Model Shop, where they re-surfaced the upper, and dowel pinned and screwed the rail to the modified A1 upper.
I initially used some 1-inch “see-through” Weaver rings that I modified to accept a Kahles 26mm diameter NATO type 1.5x scope.  I liked this scope because of its small straight tube, steel construction, rubber bumpers on each end, a low profile range dial to 600 meters (actually for 7.62), and a windage knob.  To place the rings where I wanted them, I initially used a small diameter chain saw blade file, so the round bottom notches would have parallel sides.  Over time, a few more notches were added.  For example, later I found a newer set of Weaver see-through (that fortunately placed the centerline of the scope up to almost the correct height above the receiver).  This is when at least two of the notches became square in the bottom, as the newer Weaver’s of the day had square, not round, cross-bolts.

Part Two (picture is coming):
My best recollection is that all this took place during 1983, nearer to the end of the PIP effort and my departure from Picatinny.

During this three year period, I happened to share an office and a secretary with the Canadian Forces Liaison Officer (Maj Rick Wilson) at Picatinny.  Since I well knew Canada was in the process of testing M16’s, all of the PIP items that Vince and I developed for the Marine Corps were copied to him as well, and he forwarded them to their Rifle Replacement Program Office where they generated great interest.  So they were privy to the rail upper receiver idea as well, but carried the idea forward to maturity.  So its kind of interesting to me, that their initial rail offerings were the original round bottomed notches, with just enough notches to mount their selected optic—just as in the first prototype Vince and I had made and Maj. Wilson had reported on.

When I left Picatinny and returned to the “real Marine Corps”, Vince kept the rail upper.  He subsequently convinced Mr. Jack Pritchard that something like this was what the Army needed, as well as provide an opportunity for the Army to “one up” the Marine Corps with an even “more improved” version of the M16A2.  (Note here there was a degree or two of animosity  in some small arms circles that it took the Marines to successfully improve the A1 into the A2).  Jack Pritchard was an important small arms guy at Fort Benning’s Infantry School at the time.  However, by that time, rail issues were popping up all over the place.  Canada had one design they were going forward with, and Benning had some of these.  These were called “Canadian Rails”.  Colt was in the ACR Program with a similar rail, so there was a Colt Rail.  Mr. Dick Swan of ARMS was also a player here because he needed to ensure his throw levers would work on whatever rail was finally adopted—throw levers being very sensitive to the eventual plus/minus tolerance applied to the rail’s width.

There was also a rail design coming out of the Army’s M24 Sniper Rifle System program that has a connection with Reddick Arms, as mentioned earlier in this thread (10/20/02) by QCMGR.  This design influenced the eventual square bottom grooves, the number of grooves, and their timing on the subsequent final “Picatinny Rail” aka: Mil-Std 1913.  I think it was Jack Pritchard that first used the term “Picatinny Rail” as a way to differentiate the rails under discussion at the time.  Another rail, similar to the Reddick, was submitted with the Blitz ACR Scope.  It had seven grooves, six at the rear and one at the front and was originated by Mr. Otto Repa who worked for GSI.  Interestingly, these grooves were timed one for every other groove on the current Picatinny design.  Interesting because if you take those 6, multiply times 2, this makes for 12, add 1 at the front, and you have the 13 grooves we have now.

However, chronologically none of these were the “first” dovetail rail on an 5.56mm/M16.  I think that distinction may go to Colt.

[img]www.printroom.com/_vti_bin/ViewImage.dll?userid=dlutz&album_id=118620&image_id=0&courtesy=1[/img]

This Model 656 upper receiver dates to the late 60’s.  The rail has a definite Weaver opposing dovetail cross section that measures about .580” wide.  The two round bottom grooves are about 3.20” apart.  Its a “tall rail”, slotted at the rear to accommodate a simple folding rear sight leaf.  Long’s book discusses these Model 656’s on page 64 of his latest edition.  Upon close examination of the ones here in our collection, it appears that these rails were welded on and finished–off with considerable skill.  This is understandable because investing in a new forging die is an expensive proposition just to “test the waters” with a new concept—and this concept obviously didn’t go too far.

Part three:
Back to the middle to late 80’s.  I know that one of Dick Swan’s concerns with some of these rail developments was the height of the rails above the upper receiver’s hollow center.  To explain, the Canadian and Colt ACR rails at that time were from .132” to .138” thick.  When you subtracted the depth of their grooves, you were only left with about .030” of material thickness at the “roof of the upper receiver”.  Dick believed this weakened the upper receiver unnecessarily.  Current Mil-Std-1913 thickness is about .188”.  And when you subtract the Mil-Std-1913 groove depth of .118”, the roof thickness increases to .070” (i.e., more than double the ACR’s).  So I think Dick may have had a positive influence here.

I also recall Dick telephoning me about this issue.  Mr. Swan believed I still had influence with the JSSAP people I had worked with at Picatinny, even many years after my M16A2 days,  so he asked me to lobby personnel at Picatinny as to the need for this change.  I know that I agreed with Dick’s logic, and also remember telephoning Mr. Stan Studal at Picatinny’s JSSAP Office about the issue.  Stan was familiar with Dick’s concerns, and seemed to be considering the issues.  And the issues were many, and Picatinny was but one of the players here, as every future Army sighting system was to fit the new standard rail.  However, since the thickness at the bottom of the grooves was eventually doubled to .070”, somebody obviously made the right decision.

I also recall having conversations with Mr. Studal about why the removeable Carrying Handle was only adjustable to 600 meters, but that’s another story.

I believe its important here that the Canadian Army be given due credit, as they were the first to commit to forging rail type upper receivers.  This is a very expensive proposition and took some real balls to make such decisions.  It also subsequently forced the US Army to “fish or cut bait” on rail issue.

So QCMGR and I agree that Dick Swan did not “invent” the Picatinny Rail, Upper Receiver, or what ever.  Now in all fairness, Dick has never made such a claim to me personally, and I doubt to any of you either.  However, we have read in SWAT Magazine and/or Guns & Weapons for Law Enforcement where Dick is being quoted as the inventor.   Maybe he’s being misquoted, or maybe too many of today’s gun writers don’t ask around enough or conduct proper research.

As I posted a few days ago, Long’s book is inaccurate and/or incomplete when describing the Marine Corps PIP, the Army’s involvement in the CAW program, and in other areas where I have personal knowledge.  Bottom line is don’t believe everything you read (did I say that?).  When I was in the Marines, I believed in a certain very prestigious small arms publication from England as the “bible” of objectivity.  Once I became a contractor, I found that they print anything you send them.
ColdBlue sends...

coldblue,

This is good reading, thanks.

QC

Dave,
Excellent info - I wish this was incorporated into an AR-15/M16 book.

Good info.
Got a question on the Canadian uppers vs. US uppers.
Any diference between them now?
I recall you wrote "the term "Picatinny Rail" was coined by folks at Fort Benning in the mid to late 80's to distinguish it from the Canadian Rail, the Colt ACR Rail, and others on the table during that period."

We have been told our Diemaco uppers were Picatinny, but in the latest manual, it says weaver. Now, Im getting confused here... [>:/]

Thank you.

Keld,
The Diemaco rail is...
Diemaco Rail - it has 14 notches as opposed to the 13 the Picatinny have.

It is not quite M1913 rail - most accessories will fit but the slots are slightly thinner (lengthwise) - ARMS items will not fit (unless Dick will make you some specially).
KAC, GG&G and PRI mounts work well, as do the ACOG, ELCAN, and Aimpoint mounts.

-Kevin

I am sure Dave can expound on this in greater detail

AHA!
That would explain a wandering zero on my ARMS #22M68, although it seems very secure...

Thanks Kevin,

Keld - your #22M68 fits?

It took me several hours of filing to get the #40 to fit on my rifle.  I could not get the #22M68 to fit - and was not going to file it.

Yeah, it does.

I had a #15 for my Reflex, it fitted very tightly.
Now I have the #22M68 for the Aimpoint M2. It fits, but not as tight on the levers as the #15 was.

I have seen some ARMS Swan sleeves on a couple of SF weapons too, didnt mess with them though.

Keld,

HHHMMM?

What year manufacture are your wpns?
Do they have the 13 or 14 rail slots?

Diemaco may have gone to a true 1913 rail?

On all of our Diemaco uppers (that I have used) the cross slots are to thin to use the ARMS products.

Yes, the Canadian grooves are a bit tight. When we ship our Back-Up Iron Sights to users of Diemaco Carbines and Rifles with flat-top uppers, we have to remember to turn the threads accross the mid-section of the mounting screws, or the rear sight will not sit properly on the rail.
ColdBlue sends...

Kevin,

My C8A2 is manufactured in 1996.
14 grooves.
Here's a picture of it:
[img]www.tactical.dk/images2/14grooves.jpg[/img]

And here's one with the Arms #22M68 mounted.
[img]www.tactical.dk/images2/armsm68.jpg[/img]

Wow, what kind of hood is that? Its super cool! [img]http://forums.iroczone.com/images/smiles/joke.gif[/img]

That upper does not have the fatter M4 HG's. Do the Canadian M4's lack these?

Stop it Neil [:o)]

JohnM,

No Fat handguards on the Canadian C8's.