# BUIS Assistance Needed



## GregC (3 Jan 2007)

Hey Everyone,

I've been reading up on anything I can get my hands on, searching on this site, and asking people for advice, and I just can't get a definitive answer. I am looking to pick up a METAL (as opposed to the issued plastic of course) BUIS for TF-1-07. By the way, the BUIS will be on a C7A2 with an Eotech 552. My problem is trying to find one that will fit on a weaver mount, ie the C7 flattop.

I have had none other than Infidel-6 recommend me the Troy BUIS, however upon talking to the man he recommended to buy it off, that individual said it was a no go, as police teams had issues mounting the Troy to their Diemaco rifles.

Can anyone with first hand accounts/knowledge give me a definitive answer on how to roll on this? I'd like a folding metal one, but if someone with more experience than I says to save my money and stick with the plastic irons, I'll do that.

                                                                Thank you for any help you can offer,
                                                                                  Greg


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## KevinB (3 Jan 2007)

Greg,  For flip ups I have added KAC 300m, 600m and Troy sights to Diemaco uppers with no problems, and a LMT fixed rear







P.S. Hoddie over on CGN is current using a Troy on his...







I had to file the crossbolt on an ARMS #40 to get it to fit due to the CF tolerances being slimmer than the M1913 rails spec.

The CF upper has 14 slots while the US one has 13 -- so you can push the BIS up one notch toward the front (as opposed to the rear most) -- and the rear most the receiver is already starting to narrow for the charging handle.


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## GregC (4 Jan 2007)

Thanks alot Infidel, that's exactly what I was looking for, photo's with a Troy on a CF issue upper. I'm putting in my order at CQB services today, so thanks again for the assist!

                                                                     -Greg


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## KevinB (5 Jan 2007)

a PHOTO is worth a thousand words.

Tell Joe is those LE where not so stupid they'd realise the reason why the BIS is falling off...

You can see on the pic of my SFW with the LMT fixed BIS on it that the extra notch on the rear of the receiver will not leave enough room on the aft end to properly mount a M1913 item.


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## MG34 (28 Jan 2007)

The Diemaco upper has a weaver style rail instead of the more common (in most other militaries anyways) M1913 rail,I just took a file to my upper so the BUIS would fit,after all I'm not going to damage a perfectly good BUIS to fit on an out of spec rail. ;D. Why the uppers were not junked for an updated version with a proper rail is beyond me.


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## KevinB (29 Jan 2007)

G -- you and I both know that dinosaurs rule the earth (or at least CF weapons issues...)
    Funny the C8SFW/FTHB barrels have a M4 profile -- but they used shitass C7A1 uppers so no M4 ramp in them...  GENIUS...NOT!)


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## GregC (1 Feb 2007)

Been away in "beautiful" Gagetown for a bit so was unable to reply..... just a quick update, the Troy fit without a problem on my C7, even got a chance to fiddle around with it on gunfighter a few weeks back. The sight wasn't cheap, but it's great quality, and should serve me well in A-Stan.


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## brihard (2 Feb 2007)

I6, or whoever can answer this from experience- will the Troy foldup cowitness properly with an EOtech? I'm starting to investigate what I'll invest in if I get accepted for tour. My choice of optics will of course depend on the standards of the battlegroup and on my role within it, but my initial inclination is towards the EOtech. I found it wonderful the time I got to try it out.

I have searched, but the optics and ironsight threads are numerous and cluttered, so this thread seemed an appropriate place to ask.


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## GregC (2 Feb 2007)

It will, it's the setup I used on gunfighter and what I'm taking overseas. Worked great for me.


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## brihard (2 Feb 2007)

GregC said:
			
		

> It will, it's the setup I used on gunfighter and what I'm taking overseas. Worked great for me.



Perfect, thank you.


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## Big Red (3 Feb 2007)

To put the irons in the bottom third of the Eotech window you'll want a Larue eotech mount. It will also come in handy so your Eotech doesn't fall off your rifle.


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## GregC (3 Feb 2007)

Big Red said:
			
		

> To put the irons in the bottom third of the Eotech window you'll want a Larue eotech mount. It will also come in handy so your Eotech doesn't fall off your rifle.



Can you expand on this Big Red? Not about lower third co-witness, about the "falling off the rifle" bit...... I haven't heard anything about this before, does the mounting screw tend to back out or something along those lines? Thanks for any info you can send my way, I've still got a few weeks to sort out kit before I head over  :threat:


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## KevinB (3 Feb 2007)

You really need to loctite the screw on the EO - or they have a tendency to come loose -- and bang -- you have a EO on the ground beside your gun.
  Best bet to do is use red loctite and place it thinly on the screw -- let it dry ont he screw outside the EO -- then thread it in once dried -- it will provide a sort of "locK" and make your give a good torque to remove --- this method is done by KAC on all their screws and it does help eep them from backing out from recoil and other vibrations


 The logic behind the lower 1/3 of the window is so you have the max visible in your viewfield in CQB your head is usually up higher that it would be for static shooting - making it easier to scan and to increase balance.  - you can drop your head into the irons and the EO reticle will drop down to co-witness to (to confirm zero as well)


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## brihard (3 Feb 2007)

Infidel-6 said:
			
		

> You really need to loctite the screw on the EO - or they have a tendency to come loose -- and bang -- you have a EO on the ground beside your gun.
> Best bet to do is use red loctite and place it thinly on the screw -- let it dry ont he screw outside the EO -- then thread it in once dried -- it will provide a sort of "locK" and make your give a good torque to remove --- this method is done by KAC on all their screws and it does help eep them from backing out from recoil and other vibrations
> 
> 
> The logic behind the lower 1/3 of the window is so you have the max visible in your viewfield in CQB your head is usually up higher that it would be for static shooting - making it easier to scan and to increase balance.  - you can drop your head into the irons and the EO reticle will drop down to co-witness to (to confirm zero as well)



Nifty... I'm not too familiar with the mechanics of a holographic sight, but I think I get where you're going with this- are you saying that the reticule will always appear where my line of sight perpendicularly intersects the window, so the if I raise my eye a bit, lower, or move side to side the reticule will simply shift position in the window such that I'm looking down the sightline of the weapon, assuming the sight is calibrated to begin with?


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## COBRA-6 (3 Feb 2007)

Big Red said:
			
		

> To put the irons in the bottom third of the Eotech window you'll want a Larue eotech mount. It will also come in handy so your Eotech doesn't fall off your rifle.



+1

A LaRue mount is worth the cash. It works great with the EOTech.


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## KevinB (3 Feb 2007)

Brihard -- yes, the EO reticle (if zero'ed) will always point at the tgt when you look at it.


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## brihard (4 Feb 2007)

Infidel-6 said:
			
		

> Brihard -- yes, the EO reticle (if zero'ed) will always point at the tgt when you look at it.



Damn, that's excellent.

Probably a dumb question, but I like to be thorough- the LaRue mount you mentioned has no compatibility issues with Diemaco flattop uppers? If I understand correctly it's not a true Picatinny standard...


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## KevinB (4 Feb 2007)

I've put Larue mounts on the Diemaco uppers before --if sometimes involves effort...


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## brihard (5 Feb 2007)

Infidel-6 said:
			
		

> I've put Larue mounts on the Diemaco uppers before --if sometimes involves effort...



Any actual modifications necessary?


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## KevinB (6 Feb 2007)

I'd prefer not say - since some guys are using Larue mounts   

Actually - it depends on the upper (which to me shows that the "weaver" spec rail - on the Diemaco upper has a +/- that gets near the M1913 rail specs one one end)


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## brihard (6 Feb 2007)

Infidel-6 said:
			
		

> I'd prefer not say - since some guys are using Larue mounts
> 
> Actually - it depends on the upper (which to me shows that the "weaver" spec rail - on the Diemaco upper has a +/- that gets near the M1913 rail specs one one end)



Huh... That sounds like rather shoddy quality control if there's enough variance to allow or deny a proper mount from one upper to another.

What was the rationale behind not adapting a proper picatinny and/or weaver standard?


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## KevinB (6 Feb 2007)

The CF jumped the gun.  The CF bought Dick Swan (ARMS - Atlantic Research and Marketing Systems) specifications for the rail.  At the time the US Military in conjunction with a few NATO countires (and ARMS) was working on a specification for what would become the M1913 rail.

  For reasons that I (and the US Mil - and most everyone else in NATO) cannot understand Canada decided to go it alone and do it ourselves -- funnything is that even before the "weaver" railed systems on the CF weapons had been issues the US had type standardized the M1913 rail.

You will note that the TRIAD-1 (for the C7A2 and C8FTHB) is M1913 - as is the TRIAD-II (the riser rail on the C7CT) and the C9 Rail - are M1913 spec..
  
 It should be noted that while the CF likes to refer to the "weaver spec" -- there is no such dog.  The CF has a spec for the CF flattop as done by Diemaco -- but Weaver itself is a concept -- with various manufacturers making a "weaver" rail and ring -- none of which are done to any sort of spec 
   
The CF went with an upper that has 14 slots on it, and is a touch thinner in the length (or width depending on yoru point of view) of the slot -- so itens that use a specific cross bar type recoil lug may not fit -- depending upon the tolerances.

The two (CF and M1913) rails are not that different -- so it is possible to have an M1913 accessory fit on a CF rail -- both specs have a +/- built into the spec -- as when these where done machining tolerances where not what they can be today.

I have filed down an ARMS #40 crossbar so it fit on a CF upper.  
  The Larue mounts are adjustable for tension -- so unless the recoil cross bar(s) [depending on mount they can have one or more] does not fit in the slot you should not have any troubles.  

Items from KAC, LMT, PRI, Wilcox Industries - that do no rely on the same type of clamp and recoil system should not have a problem -- however as was mentioned -- the differening shoulder angles on the rear of the CF flattop can have issues with people using the rear crossslot for a BIS (as it may not have enough avaialble rail to reliably mount the BIS) - the solution is to mount it forward one rail slot.

Secondly Diemaco/Colt Canada does make M1913 railed uppers -- just not for the conventional portions of the CF
  That has to do with the purchasers specifications -- not the manufacturer
Diemaco/Colt Canada makes a good product -- sometime they are just told to make assinine items 
   garbage in --> garbage out


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## brihard (7 Feb 2007)

Infidel-6 said:
			
		

> The CF jumped the gun.  The CF bought Dick Swan (ARMS - Atlantic Research and Marketing Systems) specifications for the rail.  At the time the US Military in conjunction with a few NATO countires (and ARMS) was working on a specification for what would become the M1913 rail.
> 
> For reasons that I (and the US Mil - and most everyone else in NATO) cannot understand Canada decided to go it alone and do it ourselves -- funnything is that even before the "weaver" railed systems on the CF weapons had been issues the US had type standardized the M1913 rail.
> 
> ...



Good stuff, thanks. I've heard LMT makes quality BUISs- in your opinion is that reputation deserved?

Sorry to keep peppering you with questions... I try to be thorough in my research.


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## KevinB (8 Feb 2007)

I ran a LMT bis during my time with the CF in Afghanistan -- doing it over - I would stick to Troy.  
The LMT is nice - I just prefer flip BIS's

Guys in the Navy that will bang off ships and suck being exposed to seawater - will really like the LMT

One problem with the LMT is the exposed left side nut -- with a stock cocking handle it can be awkward to use... Some guys have replaced them with flat nuts that make it lower profile.


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## brihard (8 Feb 2007)

Infidel-6 said:
			
		

> I ran a LMT bis during my time with the CF in Afghanistan -- doing it over - I would stick to Troy.
> The LMT is nice - I just prefer flip BIS's
> 
> Guys in the Navy that will bang off ships and suck being exposed to seawater - will really like the LMT
> ...



OK, thanks... I think that's all I've got for you. I appreciate all the info.


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