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Posted: 11/20/2003 10:43:49 AM EDT
Does anyone know the height difference between the top and bottom rail on the ARMS SIRS?

TIA
Link Posted: 11/20/2003 12:43:39 PM EDT
[Last Edit: 11/20/2003 12:43:57 PM EDT by SULACO2]
I don't know. I'd bet ARMS themselves would be more than willing to tell you though, try them. 508-584-7816. If you would, ask how much the "sleeve" raises the receiver rail, and if the "lower" rail is truely the same height as the receiver rail. I'd be interested in all of those #'s lining up. Good luck. /S2
Link Posted: 11/20/2003 1:29:48 PM EDT
Yeah, I called them today and spoke with a lady who do not have the specs, so she tried measuring it with a ruler. She said it was a little more than a 1/4 inch. Now that's some technical support!
Link Posted: 11/20/2003 1:49:21 PM EDT
The rail over the receiver is aprox .460 high. The foward bilevel of my #50 is aprox. .360 lower than the rail on the receiver. ie The front rail is about .100 higher than the receiver flat top. I figured out why and that allows the front mounted Red dot, eotech, and reflex to be where they need to be, to clear the front sight post when out there,=Trig. They did thier home work for shure! I never ask the ladies at any company that isn't in the tech dept. for tech advise that has to be measured, I just picture the meauring divice being the one she might use to measure some fabric. You know the cloth tape type:) Actually she wasn't that far off. Good shootin, Jack
Link Posted: 11/20/2003 1:51:12 PM EDT
Hah!!! That's funny. I think maybe find a way to politely "urge" them to letting you on talk to someone that knows what the spec. is. I think they'll help you out.
Link Posted: 11/20/2003 2:52:06 PM EDT
3rdtk, thanks for the numbers. Here is my hypothetical: I have an ARMS #58 that I want to mount a scope on. I can use a #35 mount without question, but it causes two issues: 1. Added Weight versus #22 Rings 2. The #35 Low rings mounts the scope a hair high for my liking. From your calculations, I theorized that I can use a #22 Medium ring on the top rail and use a #22 High Ring on the lower rail. This in turn will give the mounting surface of the entire SIR and optimal scope height. As a part of my theory I also conclude by doing so, I will have unintentionally created a .06" taper, bring the objective lense closer to the bore. (Remember guys, this is all BS running through my head). Having a .06" taper spanned across 6.2 inches of ring space on the scpoe (back to the Leupold M1) will cause minimal stress on the tube (.01" deviation per 1" of mount space). Here is the math: ARMS #22H 1.450" to the center of optic ARMS #22M 1.150" to the center of optic Difference equals .30" From 3rdtk: Height diff. of upper and lower rail .360" Total height diff. equals rail diff. minus ring diff. which equals .06" or 1.5mm Maybe it can be done? Need to borrow a High Ring.
Link Posted: 11/20/2003 4:10:11 PM EDT
I'd suggest calling back to ARMS and ask for one of thier tech reps to help. Jack
Link Posted: 11/20/2003 4:39:19 PM EDT
Yeah I could, but that would take the fun out of it.
Link Posted: 11/20/2003 4:57:30 PM EDT
LOL!!!!!
Link Posted: 11/20/2003 5:08:28 PM EDT
Why did ARMS make 2 versions of the SIR if the bi-level provides better functional use of various devices. What was the point of using a full, level 12-o'clock rail on the original #45?
Link Posted: 11/20/2003 5:20:53 PM EDT
They changed it because one of the original complaints about the system was that there was no way to cowitness with the EOthing, so ARMS took the user feedback and made it work. As Jack said, they figured it just perfect. The #45 and #46 are still the way they are because there was no reason to change them since there were new models that fixed the complaints about the previous models. That, and some people prefer the #45 and #46 setups to the bilevels. Sooo... You have a company that actually listens to end-users, has a REAL customer service department, and is forward thinking. ARMS gets a big thumbs up from me [beer] -Cap'n
Link Posted: 11/20/2003 5:29:00 PM EDT
[Last Edit: 11/20/2003 5:40:16 PM EDT by MSTN]
Link Posted: 11/20/2003 5:42:15 PM EDT
THE 45 were made for military who use PEQ2 lasers, and the flip side of the foward top rail provide a standard 1913 rail, or reverse it and it gives a built in rail for the PEQ2. The bi levels do not do it that way, but do allow a PEQ laser or other device such as an Eothing to mount. Jack
Link Posted: 11/20/2003 6:00:44 PM EDT
So then, Jack, which is "best" in your eyes - bi-level or straight? Is the bi-level more functional/flexible?
Link Posted: 11/20/2003 6:04:57 PM EDT
Originally Posted By 3rdtk: THE 45 were made for military who use PEQ2 lasers, and the flip side of the foward top rail provide a standard 1913 rail, or reverse it and it gives a built in rail for the PEQ2. The bi levels do not do it that way, but do allow a PEQ laser or other device such as an Eothing to mount. Jack
View Quote
Can you also mount stuff like OTAL instead of PEQ2?
Link Posted: 11/20/2003 6:19:04 PM EDT
At the time they designed the #45, the PEQ2 was the laser most seen in the field, and I think still is, so that is why it had that basic need built in. I like my #50 bi-level as I can mount about anthing on it, to include the PEQ2 with a PEQ2 adaptor, or if I want a strait rail, it just drops in and pins to the front hing for alignment and fastens at the rear with the captivated screw. I sure like the looks of the #58MOD with the extra rail and hand space, plus the added barrel protection though, but will prob. wait for the 6.8 to be issued out before I get the 58Mod. Jack
Link Posted: 11/20/2003 6:27:54 PM EDT
At the time they designed the #45, the PEQ2 was the laser most seen in the field, and I think still is, so that is why it had that basic need built in. I like my #50 bi-level as I can mount about anthing on it, to include the PEQ2 with a PEQ2 adaptor, or if I want a strait rail, it just drops in and pins to the front hing for alignment and fastens at the rear with the captivated screw. I sure like the looks of the #58MOD with the extra rail and hand space, plus the added barrel protection though, but will prob. wait for the 6.8 to be issued out before I get the 58 mid-length or 58Mod. if they make it in 6.8 carbine barrel length. Jack
Link Posted: 11/20/2003 6:34:46 PM EDT
Link Posted: 11/20/2003 7:11:11 PM EDT
Wes, we are both correct since we are refering to two dif. things. I was refering to red dots out front, not conventional scopes with magnification. If you notice where a red dot measures above the front sight post when mounted on the receiver, then compair how much lower and closer the red dot is from he top of the front sight post when mounted out front. It is due simular in nature of why a front post on a carbine may be too low and have to be raised even though it was ok on a full length barrel. With a red dot it is even worse since the dot floats and can wander into thev rront sight post if it isn't raised. OPTICAL DELUSIONAL TRIGONOMETRY PHENOMENA:) That's why I said they did thier home work on the SIR for the red dot/eotech types. If someone wants a strait rail for magnified optic's I can't imagine using anything other than the strait rail that the SIR has for the front of the BI-levels. CONCUR? Jack
Link Posted: 11/20/2003 7:14:10 PM EDT
COMMERCIAL: Wes sells the optional #50 rails for the top of the bi-level SIR's:) Jack
Link Posted: 11/21/2003 3:51:03 AM EDT
Wes sells 'em, and that's what they look like: [url="http://www.hunt101.com/?p=72433&c=500&z=1"][img]http://www.hunt101.com/img/072433.jpg[/img][/url]
Link Posted: 11/21/2003 3:55:51 AM EDT
Link Posted: 11/21/2003 4:08:53 AM EDT
Oh, we noticed Wes, question is are you going to make us beg? Because I don't beg for any... oh ok, please, please, pretty please, any info? appreciated. /S2
Link Posted: 11/21/2003 4:22:01 AM EDT
Link Posted: 11/21/2003 4:40:00 AM EDT
Is the 6.8mm upper expected to be true mid length, or is the #58 going to cut like the MOD? M version I'd imagine either way? Dedicated to the 6.8mm upper? What would the changes required be? I thought the only difference between the 2 upers were internal, and no exterior dimensional changes.
Link Posted: 11/21/2003 7:35:14 AM EDT
[Last Edit: 11/21/2003 7:41:04 AM EDT by 223Rem]
Bingo! So the 6.8X43 will utilize the midlength gas system. It just so happens that I have a #58 sitting right here, not doing me much good at the moment. I can always find a home this barrel elsewhere. Wes, when can I get my hands on a 6.8 barrel? Why doesn't ARMS make the additional rail for the #58, since it was designed to accept one? Does ARMS make the rail for the #59? Taking Wes' advice, I'll nix the high/medium ring idea. Although, I have seen pictures of rings being mounted on the forward portion of a Knights FF RAS, you would think that any upward pressure on the RAS would cause a slight bend/torque on the scope since the forward ring will change planes. Correct me if I'm wrong. Back to finding a compact mildot scope.
Link Posted: 11/21/2003 8:03:19 AM EDT
Just for shits 'n' giggles, I picked up a half spacer for my #22M68 to see how I'd like it on the forward rail of my #50. Aside from looking extremely ghetto, the rear cap wouldn't flip down all of the way and moving the Aimpoint forward to compensate put the front cap down on the front sight tower. Oh well, live and learn!
Link Posted: 11/21/2003 6:21:03 PM EDT
YEP, you would need the full spacer out there. I don't know what they use the half spacer with. Jack
Link Posted: 11/21/2003 6:37:28 PM EDT
The full is way too high. Out of curiousity, I flipped my cantilever around and tried it out front before I Loctite'd the ring to the base to mount it on the top rail. I had planned on putting it where it is now (over the delta ring), but I was just a little interested in my options.
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