Need a Long Rail (12-16") to Mount to 6" Rail

[Strykervet]

I have an M2HB with a KAC tri-rail optic mount on it. In short, I need to extend that rail some forwards and back. I have a 6x48 ACOG and a PVS 30 I'd like to use in front of it. I need a rail long enough to accommodate both mounts, I'm assuming 12-14" would do it but I'll have to get it out to measure exactly. I'd like the bottom rail mount to be located somewhere along the rail such that nothing will interfere with the feed tray. This'll cause the ACOG to stick out the back a bit, which is fine. If I could get this so I could add a block to elevate it, that'd also be a plus. I suppose longer bolts could be used between the mount and the rail to accommodate that and I could DIY that. I'd like for it not to cost a fortune and it seems like a perfect DIY project all around.

I'm having a hard time finding something like this. PRI sells some lengths of rail but I'd need a mount that would work, that the rail can be bolted to. They have a steel and aluminum rail, but I'm concerned about them holding up the weight. I suppose I could make a support but a beefier rail would be best. Then there was something on Amazon sorta like this but it looked really cheap.

A QD mount probably won't cut it given the weight of it all and the fact it's gonna be cantilevered some. The biggest and toughest bolt on mount I can bolt to a rail would be best. Something designed to actually hold a rail would be a plus too. I know something is bound to be out there, I just don't know where to look. Hoping someone here will.

Thanks. And Happy New Year!

 

[Strykervet]

Nobody have any ideas on a section of long rail that'll fit to a shorter one?

 

[shoobe01]

Well it was new years. Most people won't be online until tomorrow.

QD levers are generally as strong as bolt on systems. I wouldn't worry about that, even on a .50 yes. Seen some of the M2 add ons specifically that are held with throw levers.

I am not sure what KAC rail you have (not familiar, not getting anything from googling) so am trying to picture if a giant canteliever is the right answer. For other MGs, I have seen folks use two different rails. Say on the Minimi or Mk46, the sight is on the receiver cover and the clip on is on the chunk of rail over the barrel. Then you get the space, but no cantilevered systems. There are such over-barrel rails for the M2 as well.

I just yesterday was bolting a chunk of plain old pic rail to something for a very different project and NO, the rail alone won't hold any weight. Has to be secured to another base. The extensions I have seen for precision rifles that approach that length, even with reinforcements, still flexed under load/recoil.

I might bug someone like Cadex to see if they have a product that can solve the needs, or can modify or make something from some of the other bits they have laying around. I bet they can fix it.

 

[Waorani]

Nobody have any ideas on a section of long rail that'll fit to a shorter one?

I don't know either but your earlier post about the 6x48 ACOG for Xmas just cost me $1200! I've got the scope mount that slides over top plate as well as a picatinny for rear sight dovetail but thinking about getting one of these for a good solid mount or making something similar.

 

[Strykervet]

Yeah, I guess New Years is slowing it down...

Funny you mention Cadex... They make two mounts that would work awesome, but the cheap one is $4k I think.

There is a Hellfighter lamp kit that goes on this and you can get rails for it (or just buy some and drill the holes) that bolt on but they're way too far forward to be of much use. And it's not THAT stable.

The mount I have is the KAC tri rail, I think it shows up under military parts on one of their sites. Anyway, it slides over the rear of the gun over the sight and it leaves a window in the bottom big enough to use the battle sight but not the vertical adj. one. It clamps in several places to the gun. There's a rail on top and one on each side. R side has an IR illuminator. If you notice the top rail, it's longer than the side ones and extends back about an inch or so. You can see the feed tray doesn't have a lot of room, so the rail will definitely have to cantilever off the back a good 6-8 inches.

I figure if I can find something that'll work, that I can probably reinforce it or get it done. Having a rail bolt to the base would be best because I'd like to be able to put a riser between the base and rail. I guess that depends on what's available.

Here's a picture of it at the range a while back. The top rail is clearly visible.

 

[Strykervet]

I don't know either but your earlier post about the 6x48 ACOG for Xmas just cost me $1200! I've got the scope mount that slides over top plate as well as a picatinny for rear sight dovetail but thinking about getting one of these for a good solid mount or making something similar.

View attachment 6995790

You found one for $1200? Where at? I went back to Amazon to do something else and it asked if wanted to order another. So I clicked on "buy it" to see what it would say. Was $2180 or something? I got it for $1448 and there was only the one, so had to be a deal from Trijicon. I still had to shell out another $200 for the ARD and flip caps, but those caps are a LOT better than Butler Creek.

Did you get it used on Ebay? That's where I get most of my ACOGs because of the warranty but I couldn't find one for less than Amazon had it.

That base certainly looks solid, but the clamp on one KAC makes that uses several set screws is pretty stable, it doesn't move. There's another tri-rail and the dual rail that have the QD levers but I don't know much about those (not KAC). Mine has red Loctite on the screws and came with big allen t wrench to install it with, so I think it was meant to stay put.

 

[Waorani]

https://www.gunbroker.com/item/793253934

I'm seeing some 12" picatinny risers on google images but most don't look well built. Surely there's something out there.

 

[Waorani]

I've also got one of the long Hellfighter mounts. Don't like how it's canted a bit. Not sure if it's supposed to be that way or if the holes in newer barrel support are aligned a little different allowing the light to hang straight down. I'm in the market for one of the short HF mounts if anyone has a lead on one.

 

[shoobe01]

Hey, you acquired and have to feed an M2, I assumed price was no object

On the other end, yes: a $29 riser seems like asking for trouble on this application. https://www.amazon.com/high-Tactical-Picatinny-Cantilever-Riser/dp/B00JQM9DLU

Gunsmithing would seem to be the way then. I /think/ I'd start with a reliable clamp/lever on mount, a store bought chunk of aluminum rail (even cheap eBay rails tend to work well enough IME), and get someone to machine an aluminum reinforcing block. Screw the rail to the block several places, screw the block down to the clamp mount. Since it's modular, maybe you could try the cheapass riser as above, but shitcan their clamping, machine a block to interface with a good base to attach to your existing rail.

E.g. take the LT100 for the "ACOG" (really, anything designed to fit on the AR carry handle) and build something for the top of it. The mount pattern should be strong enough; the OAL of the old canteliever mounts the first M68s used were this long, just with that weird step down.

 

[skinnj1]

https://alcobrametals.com/guides/custom-blank-picatinny-rail

 

[shoobe01]

Ooooh... enough depth it might actually be rigid on it's own.

I'd probably machine out a groove along the middle to lighten it up but otherwise nice find for the rail, saves a step, presumably actually machined to spec also!

 

[Waorani]

The mount I have is the KAC tri rail, I think it shows up under military parts on one of their sites. Anyway, it slides over the rear of the gun over the sight and it leaves a window in the bottom big enough to use the battle sight but not the vertical adj. one. It clamps in several places to the gun. There's a rail on top and one on each side.

Not seeing anything on KAC, wonder if they discontinued? This one looks similar.

Also good find on the picatinny blank. That could be a nice find if in spec. I've bought a couple off ebay over the years and they weren't in spec.

 

[shoobe01]

...I've bought a couple off ebay over the years and they weren't in spec.

I've gotten a number of name brand ones that I paid good money for that were not to spec. Cross-slots are very often too tight to mount in-spec (I measured) accessories. Judicious use of my Al file and blackener is all too common around here.

 

[Waorani]

Holy crap, the 6x48 ACOG is huge and almost 3lbs! PVS 30 looks like another 3lbs so together they're going to need something pretty beefy. The aluminum picatinny blanks ain't gonna be it. Guessing anything you could get both on would have to be pretty serious custom.

 

[strikeeagle1]

You might consider fabricating one of these LaRue S.T.O.M.P. style configurations.

 

[Strykervet]

You might consider fabricating one of these LaRue S.T.O.M.P. style configurations.

View attachment 6998115View attachment 6998116View attachment 6998117View attachment 6998118

The mount I have is similar to the one you have there from BMG parts. I've seen those at surplus stores too, so army does use 'em. They use quite a few actually. The KAC one is a military part and on one of their pages (they have a few) it shows it. The KAC one is a bit less bulky and the rails are made into the body, I don't think they come off. Or maybe they do bolt on. But they go in one place. It's well made of course. Not QD, it uses large set screws to clamp to the rear of the gun.

Hey, that Larue stuff might work! Let me give them a call. Thanks. I thought about it, the forgot. I'd need to use it backwards from how you have it though. I need it to extend out the back, not the front. That'd interfere with the feed tray. I still worry about cantilevering a PVS30 on a rail like that. But maybe it'll take it, I don't know. It does look solid.

I can get rail from PRI that's good if I have to make one. I figured I could use a some kind of ARMS mount or whatever, and bolt the rail to a strip of steel to beef it up, and bolt that to a riser, just an aluminum block with holes drilled through it so I can put it between the rail and the mount.

But I'd like to avoid building it if possible. If I can find a decent setup for not too much. Not as cheap as what's on Amazon, I need better than that. But not $500 or anything, I'll build it in that case.

Yeah Shoobe, when I bough it I was married and finances were bit better. The M2 is a never ending need for the next part, and everything is expensive. I load for it and it's still expensive. So anywhere you can save a bit, you need to go for it! Wouldn't have bought this ACOG if they weren't giving it away like they did.

Thanks for all the ideas guys, keep 'em coming for now! If any of you think of a similar setup or some kind of modular rail extension, etc., let me know!

 

[Strykervet]

So the Larue part is too expensive, thousands. One includes a Leupold 12-40x60mm, which is really nice, but I can't afford that and I just built an observation scope/LRF setup. They don't sell that rail alone as far as I can tell.

I found this looking around, I don't know if it'll work but it's 11.5". I think the bolts may be adj. but it's not a picatinny so I don't know if the PVS 30 will even fit? Or the ACOG?

https://www.opticsplanet.com/armasight-long-rail-adapter-for-clip-on-day-night-system.html

It's all I can find without having to make my own I guess. What a pain. You'd think someone would make a long picatinny rail that clamps on. For a variety of uses.

Edit: it's 12" from base to base so I'll need a 14" rail at minimum most likely.

 

[Strykervet]

So I measured it and it's 12" exactly from the end of one mount to the other, so I'll probably need 14" to be safe, so the mounts line up. But there isn't anything I can find that looks sturdy.

I found this for $140, 16" carbon steel 3/4" tall. There's also one just like it in 7075 for $70 I'd rather use. I just have no way of mounting it to a base, they all require machining of this rail of some kind. Anybody know of a place with good prices that'll do that if I send 'em the parts? It'll still be costly with the rail and 2-3 QD mounts (unless I can find some kind of bolt on mount that'd work).

Here's the rail EGW has, 16" and it comes in carbon steel and 7075 anodized black. Looks very solid, I'm sure it'd work.

Hell, I constantly need all this custom shit, I'd go ahead and get a tabletop mill and lathe now if I could afford it. But I need to be able to move in a year and a few months so I can't really budget something that expensive in right now (unless I found someone basically giving it away in CL or something). It's always something, I swear.

 

[Waorani]

Thought it would end up longer so good solid aluminum rail like the EGW would probably work. There's some cheapo QDs on ebay but the one I got a few years ago out of curiosity is pretty poor quality. Don't know of a shop but it shouldn't be that hard if you find some nice mounts. I may experiment a little but am too much of a novice machinist to work on someone else's parts.

Also - looks like the KAC is PN 99207 - M2 and MK19 RAS. Can't find any for sale anywhere though.

 

[Strykervet]

Thought it would end up longer so good solid aluminum rail like the EGW would probably work. There's some cheapo QDs on ebay but the one I got a few years ago out of curiosity is pretty poor quality. Don't know of a shop but it shouldn't be that hard if you find some nice mounts. I may experiment a little but am too much of a novice machinist to work on someone else's parts.

Also - looks like the KAC is PN 99207 - M2 and MK19 RAS. Can't find any for sale anywhere though.

Hey thanks, that's kinda what I'm coming to the realization of. It's gonna have to be made (of course it does!). The EGW is the only 16" rail that looks suitable. They do sell a 32" extruded aluminum rail and several other extruded options but those aren't as thick as the HD rails. I think I'd be okay with 3/4 thick 7075, steel would be nice but it's not worth the price I don't believe.

I looked up that part number, and I found ANOTHER KAC catalog. How damn many do they have? Anyway, that's the part, it's just a three rail setup like the others only this one is a bit more compact and probably won't interfere with the optics and electro optics seeing through the armor plate. The one BMG sells (which is a military part BTW) seems like it would be more useful but it's wider and I scored the KAC part on ebay for cheap.

I wonder if a mount company, maybe a smaller one, would do the work.

 

[Waorani]

I like the looks of the KAC and am keeping an eye out for one. Also, good bet the EGW rails are in spec vs some of the cheaper options.