I am in the market for a forend rail system. I need some help on weighing the pro's and con's of these two differant systems. Knights has the RIS, RAS, and the RAS2. ARMS has the SIR which one is better and why?

KAC RIS and RAS is not free float, RAS2 is free float and will not require tools to install, it is the same concept as ARMS SIR. free float RAS requires disassembly to install and it is my current favorite.  you would go wrong with any of the fore arm you choice, it all depends on what you want out of it.  

List your requirements and what you expect to do with the handguard and lot of knowledgeable folks here will steer you to the right direction.  

FF RAS would be my absolute favorite if there was no disassembly required. So its my 2nd favorite, first being SIR.

But I have to admit full length SIR looks very heavy. I'm leaning on FF RAS or at least M5 RAS for rifle forend.

If you are willing to pay gunsmith or take time to do it for yourself, I'd recommend FF RAS. Free floats, lightweight, rugged, looks conventional with rubber guards. SIRs do look funky but if you want an uninterrupted rail you want a non-bi-level SIR. KAC is coming out with URX in the future which also has uninterrupted rail.

I've lost count. Hasn't Knights sold something like 80,000+ RAS kits to the U.S. Military. That's not counting foreign military units that have purchased it also. The non free float issue doesn't seem to bother them.

This is why in the SOPMOD 2 upgrade one requirement is to have free float RAS style handguard.  all the major manufactures are all pitching their new free float rail handguard at this time to the Gov't.

If gov't is purchasing solely from KAC, their option would be RAS 2 as of current for URX in the near future.

For carbines, I think RAS 2 is best of both worlds - free floats and it is user-installable.

I'm looking at the RAS family.  I want to mount my EOTech at, near or forward of the "bridge" or gap where the flattop stops and and the RAS begins.  I will not be using it for 200 meters or farther.

TS

My point is that its "just a dam handguard". Get a grip. Are you telling me that if you went to the range with both a free float and a regular RAS kit, you could tell the difference? I think not. The regular RAS kit will do just fine for every dam one of us. Do you think U.S. Special Operations command is just going to junk its RAS kits? I think not, they will be using them for many years to come. They will just slowly be replacing them over years with whatever gets chosen for the SOPMOD2 upgarade.

Just buy a Knights S-4 and be done with it ;)

Ummm...OK!  [ROFL2]

As for SOCOM junking RAS units......NO! They are being used by many Units/Divs. that aren't under SOCOM and I bet they'll work their way down to the National Guard!

I thought you could figure out that I was just using the Special Operations Command as an example.

It's easy to tell the dif. if it's FF or not, when you start shooting alot, heat, malfunction, etc. Spec ops weapons/equipment is ordered/type classified thru Naval Surface Warfare-Crane. They did not buy the RAS, only the RIS. After numerous documented reports of bad experiences and complaints from the troops in the field, plus further evaluations at Ft. Bragg, Crane, etc. all fure systems will only be FF according to the solicitation. They will only buy a FF system based on all the bad experiences with rails attached to a barrel. The solicitation is for almost 93,000 FF rails. They need a system that can handle all the advanced electronics that will be able to be intergrated into a more compact overal package, by selecting where the rails will be if needed, covers not required over anything that the soldier has no use for, and easy to install to the host weapon. I can't imagine tearing down 93,000 weapons to put a handguard on, espec. if it is based on an old concept of built in rails/panels that has already had many problems. The SIR was developed to address those problems, and then Cranes solicitation came out afterward, that tells me alot.
It will be interesting to see what they select.
Good shootin, Jack