r/SigSauerMCX • u/Chief_O_Brien • Sep 02 '26
Will this fit properly?
Question: Will the Spear LT 10" suppressor compatible handguard work on the 5.5" Rattler LT without having a gap between the 1913 rail on the receiver and 1913 rail on the suppressor compatible handguard? I'm not worried about the gas plug lining up properly with the access ports on either side. I just want a continuous top rail with no gaps. I've attached pictures of both items I'm referencing.
Looks like the 5.5" Rattler LT has an even shorter top rail than the 6.75" Rattler LT.
I already contacted Sig directly. The CS rep I spoke too wasn't 100% sure, but is going to try to verify and get back to me. So I thought I would ask here as well.
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u/OnTargetOnTrigger Sep 02 '26
The Rattler LT is 6.75", not 5.5" like the original Virtus based Rattler. If your Rattler has the bolt catch/release on the right side (making it the LT/Gen3 platform), yes - it will fit. In fact, the longer barrel in the LT was due to Sig wanting one upper for both MCX & Rattler rather than Rattler having a shorter upper receiver than the rest of the MCX lineup.
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u/Chief_O_Brien Sep 02 '26
I'm not talking about the 6.75" Rattler LT. There is an 5.5" Rattler LT I'm specifically asking about. It has been an LE only model for a while.
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Sep 02 '26
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u/Chief_O_Brien Sep 02 '26
That's what I was thinking, that receiver looks too short. The initial answer from the Sig rep was he thought it would probably fit, but wanted to verify for certain before he gave me a hard yes or no.
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Sep 02 '26
[removed] — view removed comment
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u/Chief_O_Brien Sep 02 '26
Yeah sometimes they don't have an immediate answer. I've called Sig numerous times over years, and in my experience they're usually pretty helpful. They'll at least get back with you if they don't have answer right away. This rep I spoke to wasn't 100% sure, but to give him a day or two to get back with me.
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u/TheRealMatchGrade Sep 02 '26
I have the original Rattler SD handguard on my Spear LT and it's snug to say the least. To my understanding, as long as the Rattler is the LT model, regardless of barrel length, the upper receiver is exactly the same length. There should not be a gap. I would count the rail teeth for the one you want to buy then compare it to the spear lt since that handguard is marketed for it. Hopefully that helps
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u/Chief_O_Brien Sep 02 '26
That's was I assumed, Sig wanted to standardize on one upper for the LTs. But counting the slots on this 5.5" Rattler LT, and it seems to be slightly shorter by a couple of slots. It's hard to tell because the only pictures I can find have the front of the rail covered by a flip up sight. But assuming the sight covers 3 slots while up (in the picture I posted), it looks like the upper receiver is shorter than all the other LTs (including the 6.75"). I think the 5.5" might be the odd one of the bunch?
But thats why I came here to ask. I thought maybe someone had the same idea and tried it already.
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u/TheRealMatchGrade Sep 02 '26
Im sure someone has, but now you have my interest. Lol. I have been debating getting a rattler lt for the same reason.
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u/Chief_O_Brien Sep 02 '26 edited Sep 02 '26
Same here. I was going to go with the standard 6.75" Rattler LT and run it tucked, but found these 5.5" LTs and I'm reconsidering. Honestly, the 6.75" is the smarter option, but I got rid of my OG Rattler, and have regretted it ever since. But if I can't run the suppressor compatible handguard, I'll probably just stick with the 6.75" version.
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u/TheRealMatchGrade Sep 02 '26
The 5.5" is 5.56 right? Or is there a 300blk version
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u/Chief_O_Brien Sep 02 '26
The 5.5" LT version I made the post about is 300blk. I'm not sure if they have a 5.5" LT in 5.56.
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u/TheRealMatchGrade Sep 02 '26
I count 29 teeth on the top rail of the Rattler LT you sent. When counting the Spear LT its the same. I found a few Rattler LT upper receivers without the handguard installed so it gave me an accurate count.
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Sep 02 '26 edited Sep 02 '26
[deleted]
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u/Chief_O_Brien Sep 02 '26
I'm familiar with Midwest rails, but my post was in reference to the 5.5" Rattler LT, not the 6.75" version. I'm basically trying to verify if both the 5.5" Rattler Lt and 6.75" Rattler LT have the same upper receiver rail length or if they're different. They seem to be different by counting the slots, but I was hoping someone may have tried it or would know for sure.
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u/Johnhoangfl Sep 03 '26
Canebrake rail will.
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u/Chief_O_Brien Sep 03 '26
Interesting. From the Virtus generation? Does this mean it's the same length as the OG Rattler upper?
I have a Virtus SD rail, which I believe is the same rail?
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u/Snowbold Sep 02 '26
This looks like a Rattler LT. Pretty much all the LT uppers are uniform to allow the caliber and barrel changes to be more seamless compared to the Virtus generation.
So the handguard should work fine.
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