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Posted: 4/5/2007 12:03:25 PM EDT
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Whats the point of the ARMS #38 extended rail on the Mk12 Mod0? Is it necessary? I ask because the the Mod 1 doesn't have the rail. Is the PRI tube not as strong or rigid as the KAC rail? What are the pros/cons of each system? |
| The rail allows you to mount your optics as far forward as you deem necessary. The PRI tube is very sturdy. One downside to the continuous rail is that you are limited to a 40mm objective scope, unless you use high rings, which will ruin your cheekweld. The mod 1 is considerably lighter, but I like the looks of the mod 0 much better. Ive been collecting parts to build my own for over a year and its nearly done. Im stayin with a 20 inch barrel though, so it wont be a perfect clone. |
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I wouldnt know for sure, but when the SPR's first came out theu used the Leupold LR/T 3.5-10 optic. This scope was not designed around the AR platform and its propper eye relief required you to mount the scope much further forward on the reciever than the small amount of rail the flat top would allow. The ARMS SPR mount gave you one solid rail to mount the optic wherever you needed to. This was all before LaRue SPR optic mounts, MRPs and the like. Shortly after, Leupold build a new scope. Commercially it was the MR/t 3-9. This scope was built around the AR and did not require so much eye relief. I had never seen the LR/t on a Mod1 SPR... maybe by new MR/t's were released by the time the Mod1's came around, and the long rail was no longer required? I dont know... just a guess. |
I was wondering about the obj diameter on the way home just now; that makes a lot of sense. Seems like you could run the PRI without the ARMS rail and it would be able to support an objective of even greater diameter than one could run when using the KAC rail, while keeping the same optic height, and be lighter for it. Seems like the PRI+LaRue SPR mount is the better all-around solution here, no? |
Meh, Im not sure about that. the PRI barrel nut assembly is much fatter than that of the Knights. So much so that it would restrict how far forward you can mount something like LaRue's SPR mount. In addition, the top rail on the PRI is at the same height as the top rail of the Knights rail. So unless you took the top rail off the PRI (which is possible), there would be no more clearance between the two. How big a lens are you wanting? There's a lot of room when you dont use the ARMS rail on either. |
| Well, if you put the LaRue mount on top of the ARMS rail, yeah, you could mount something bigger. However, the LaRue mount is ideal for mounting directly to the flat top. Standard LaRue SPR mounts raises the optic 1.5", then add another appx. .5" for the ARMS rail. That would put you optic up higher than most would like. |
The top rail is out on the last 2/3 of the PRI tube though, so where the optic objective would be, just forward of the barrel nut, there would be more clearance, right? I had no particular optic in mind, I'm just thinking about maximum flexibility; I guess a 56mm IOR or Nikon would probably be the largest optic I would consider. |
The top rail that comes standard on the PRI tube is long on the top. It covers about 2/3 of the surface on the top. Like I indicated, the rail is not only removable, but you can switch it for a shorter rail like the ones on the side or bottom if you like. If you use a LaRue SPR scope mount, use a KAC tube, or, just skip the ARMS rail and use the PRI tube, you have plenty of room for a 50mm lens on your scope. I have never mounted anything larger than 50, but you may have room even for something bigger. |
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