Opinion on the SIR
 

Seems there are folks who love 'em and swear they're the best rail system out there. I had one (#45) when they first came out but fairly quickly swapped back to KAC. I must admit when it comes to rails systems I'm a bit biased but open to anything that is an improvement.

I've read all sorts of stuff like they were booted from BlockII but held things up and won a GAO protest to the Rangers wanting to use them, etc., etc.

Anyone have any thoughts on what makes this forend better/worse than what is in use by the Military today?

Take care....

Much better cooling and heat dissipation than the RIS/RAS. Would make an excellent platform for attachments on a dedicated automatic weapon.

A little bulkier, but that has supposedly been addressed with more recent models.

Slightly more difficult to install the military version.

HTH.

TR

I have found the SIR a bit heavier than its worth, IMHO. The KAC FF RAS has been my favorite so far.

i prefer the KAC RIS to the SIR myself. i have the SIR #50 (slimline, bi-level); here's my personal and non-professional .02 about the SIR.

likes:
1. easiest free-floating rail to install (at the time i bought it). both the civvie and military version are relatively simple to install.
2. cooling (like reaper mentioned), but i use a vert grip so that doesn't really affect me

dislikes:
1. raises the flat top up. cheek weld suffers (slightly) if using an ACOG. eotech cannot co-witness (unless mounted on a bi-level on the front).
2. you can only use an ARMS BUIS.
3. adding side or bottom rails requires tools (a coin or screwdriver) and you have to find your rail.
4. doesn't come with full length side or bottom rails (you might not need them).
5. plastic lower handguard has some sharp edges - not as comfy as the standard M4 handguards or a RIS with rail covers
6. more bulky than the KAC with rails exposed
7. need a full length rail (#4, not supplied) on the bottom when using a vert grip - the short ones don't provide enough support with one screw and tab
8. none of the rails on the SIR are mil-std 1913 compliant. not a prob with most accessories, but won't fit a TD vertical grip which IS 1913 compliant

i just think the KAC does it in a more compact package, but it's just personal preference. a FF RAS would be one of my top choices (i have the KAC FF MRE version)
but i like the LMT MRP better than either the SIR or the RIS/RAS.
cheers,
MM

Agree
 

I have to agree with all of this and I also see The Reaper's point about it being a good platform for a dedicated full auto weapon with it's cooling enhancements. Be nice to have a model for something like a SAW, etc. perhaps? I just like the simple, everythings were you need it philosophy, with the KAC forends. The FF RAS is a great piece I agree. I have one on my rifle though without the MRE.

My main complaint with the SIR models is too many little parts to lose or break. That and the full length upper reciever rail.

Thanks for the replies folks
Take care...