BUIS Assistance Needed

[brihard]

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?

 

[KevinB]

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

 

[brihard]

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

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.

 

[KevinB]

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.

 

[brihard]

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.

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