Im hanging around here quite much latly but I cant recall having seen an arms SIR of any model here latly
how come. Do you think they are yesterdays stuff and rather prefer troy or larue
I mean they have no as much attachment points for extra stuff as the usaul rail design
but I think they have enough anyway.
so how come they have seem to decreased in popularity?

Quoted: so how come they have seem to decreased in popularity?

Because better, cheaper, and lighter weight systems have been developed since the advent of the SIR.

they use to be everywhere.

Quoted: Quoted: so how come they have seem to decreased in popularity? Because better, cheaper, and lighter weight systems have been developed since the advent of the SIR.

Yep, they were everybody's darling a few years ago.  There's nothing wrong with them per se, but better systems can be had for much less.  If they had an MSRP of $200 or so, they might have more followers.

ARMS has the SIR priced dealing with the market of several years ago.  Until they revamp their price structure, and make a new version, you won't see many of them.

Perhaps this Shot Show will release the version that they teased us with last year, but unless the price is in line with other companies, it will sit on shelves.  

One thing I think is pretty interesting is how long ff systems (9"+) can get the stability just from the barrelnut (troy and samson) or the including attachment systems like DD or larue nad even KAC.
I mean the sir and KAC rasII seam to get a lot of stability support from the reciver aswell.
On shorther models there is not that much momentum in the ras as in the long ones so maybe SIR gives a bit better stability when the gun is really really rough handled? (like combat)
this is just some of my thoughts, now I want to here the opinion from the guys who actually know their shit  (you)

Some people don't like the elevated receiver rail due to not being able to co-witness with some optics.

WOOO!!!   I love my SIR system!!!!
Never said I wasn't behind the times a bit...
Don

You're about 2 years too late.   I remember when the bi-levels, slimline and green models came out and everyone was like, "Ooh, ahh!"    Times have changed I guess.    

The SIR is still a good system for some people.  But the issues I had (yes I owned one) were better rectified with a different rail system, Larue being my choice.

When mounting a light at 3 o'clock with a VFG at 6 o'clock it placed the switch way too far away from my thumb.

Unless I spend even more money the longer accessory rail mounting a light at 6 o'clock was impossible with a VFG on that same rail.

Being limited to an ARMS and ARMS only rear BUIS.  I love the #40 but I hated being limited to only that BUIS.

Same goes for the top rail.  The inability of mounting a rail mounted front site of some sort was a severe limitation in my opinion.

The one big bonus to the SIR was it's ease of installation I will admit.  And yes, it is a very strong system as well.

You won't find me knocking the system,  it's just simply not the system for me anymore.

Back in the day they were decent kit. However, compared to modern products they are heavy, complicated, and they do not hold up as well. Unless you loctite all the threads, the thing will fall off.

  I like mine.  I will admit that it is a heavy piece but I'm not planning to hump it too far.  I wanted a FF system which had a continuous rail from the rear of the receiver to the FSB and I found two options.  A KAC RAS with an A.R.M.S. full length sleeve over it or the S.I.R. system.  (You can screw the sleeve down into the KAC RAS.)  The cost of the KAC and A.R.M.S. rail would have been comparable to the S.I.R. so I decided to go with the S.I.R..  I wanted the ability to mount an optic at any point between the FSB and BUIS.  
  I have had one issue with my S.I.R. and that is two of the thread inserts on the polymer handguard have slipped and I can not get my 6 o'clock rail off of the handguard. (A.R.M.S. promised to ship me a new one.)  Other than that, I got exactly what I was looking for, a rock solid platform with a full length, uninterrupted rail.  All things considered, I am happy with my decision.

I'm totally satisfied with my S.I.R. #51C.  Someone else can spend their money on "WOW products of the week".

http://blueridgeschool.photosite.com/~photos/tn/1139_1024.ts1135265339419.jpg

Quoted:   I like mine.  I will admit that it is a heavy piece but I'm not planning to hump it too far.  I wanted a FF system which had a continuous rail from the rear of the receiver to the FSB and I found two options.  A KAC RAS with an A.R.M.S. full length sleeve over it or the S.I.R. system.  (You can screw the sleeve down into the KAC RAS.)  The cost of the KAC and A.R.M.S. rail would have been comparable to the S.I.R. so I decided to go with the S.I.R..  I wanted the ability to mount an optic at any point between the FSB and BUIS.     I have had one issue with my S.I.R. and that is two of the thread inserts on the polymer handguard have slipped and I can not get my 6 o'clock rail off of the handguard. (A.R.M.S. promised to ship me a new one.)  Other than that, I got exactly what I was looking for, a rock solid platform with a full length, uninterrupted rail.  All things considered, I am happy with my decision. img520.imageshack.us/img520/384/fxh2yp5ys.jpg

Me likey

phylo, kisara, others................

How does the S.I.R. connect?

Are those screw-type attachments- at the upper receiver rail- anchors?

Is the barrel nut and other hardware intact underneath the 'skirt'?

TIA



ETA: I see from 1911gunner's pic, the latter seems to be true.

www.armsmounts.com/sirSystem.html

http://www.armsmounts.com/images/img116193.jpg

Quoted: One thing I think is pretty interesting is how long ff systems (9"+) can get the stability just from the barrelnut (troy and samson) or the including attachment systems like DD or larue nad even KAC. I mean the sir and KAC rasII seam to get a lot of stability support from the reciver aswell. On shorther models there is not that much momentum in the ras as in the long ones so maybe SIR gives a bit better stability when the gun is really really rough handled? (like combat) this is just some of my thoughts, now I want to here the opinion from the guys who actually know their shit  (you)

This is perhaps the thing that I like the least about this these types of handguards... that barrel nut was never intended to support this load and using it for a handguard mount only makes the barrel/receiver alignment flex more. This is a known issue and attributed to the rise in broken bolts amoung other problems.

There are a few people that are working on a reinforced upper receiver and handguard attachement methods that do not lean on the barrel nut... The systems that you can check out now are of course the ones that attach to the receiver (ARMS, CASV, ETC) and Colt has a pretty clever idea of mounting the HG on the M5...

gunzilla: as I tought.
thansk for nice pics and answers

My Dissy. It's quite the pig.

can you say heavy?

Can you say strong?

I had a SIR on my M4 for about 3 years and a few weeks ago I put a KAC RAS on my M4 and couldn't believe the difference!  Talk about weight loss!!

I liked my SIR but I guess I have come full circle.  I had a RAS on before the SIR, now I'm back to the same thing.

I'll admit the SIR bulks up the front end like no other BUT, I wouldn't have any other rail system on my M4 ( I can call it that since Colt lost ) the thing would be indestructable if it had an aluminum lower HG sure would add weight but WTF 7-8 ounces? Sorry Combat Jack I have had mine on without locktite for 3yrs and nothing has fallen off shot loose or malfunctioned and what is so complicated about it... less complicated than waiting for a gunsmith ? There is just something very sexy about the way the SIR looks ...IMO  

I bought mine second hand after they fell out of favor for $200. It does help a lot with cooling, and the weight doesn't bother me since I only have to carry it to the firing line. I've run thousands of rounds through it full auto and never had problems with it loosening up. For what I use it for, it's perfect.

I was on the phone to KAC to get an RAS I swear , but I felt after my contact I felt that I did not want to be a KAC customer I'll leave it at that, I received an apoplogy here on the boards after all my pissing and moaning from a righteous brother and AR15.com member who works @ KAC and I really appreciated it but by then my $400 had already been spent by the Swans but after much debate regarding the Ras maintaining a zero with an optic on the top rail since it does not freefloat the barrel rigidly I was very glad I got a SIR.
Now I am not trying to open a can of worms by stating the RAS can not hold a Zero. But how can any four rail system that is not rigidly mounted in any other fashion than what is designed to hold plastic handguards maintain sight zero? The RASII fixes that but with the cost of lump in the middle of the upper - not a slag just an observation. It seems an expensive option to only be able to attach a light and a VG since the wobble issue will persist regardless of what I think.
A newbee who buys a 4rail system which does not mount rigidly because so and so has one and then learns what freefloat is and does will learn the hard way because AR's are an expensive and unforgiving addiction by spending hundreds of dollars needlessly... the most painful of all lessons learned.                

Quoted: I was on the phone to KAC to get an RAS I swear , but I felt after my contact I felt that I did not want to be a KAC customer I'll leave it at that, I received an apoplogy here on the boards after all my pissing and moaning from a righteous brother and AR15.com member who works @ KAC and I really appreciated it but by then my $400 had already been spent by the Swans but after much debate regarding the Ras maintaining a zero with an optic on the top rail since it does not freefloat the barrel rigidly I was very glad I got a SIR. Now I am not trying to open a can of worms by stating the RAS can not hold a Zero. But how can any four rail system that is not rigidly mounted in any other fashion than what is designed to hold plastic handguards maintain sight zero? The RASII fixes that but with the cost of lump in the middle of the upper - not a slag just an observation. It seems an expensive option to only be able to attach a light and a VG since the wobble issue will persist regardless of what I think. A newbee who buys a 4rail system which does not mount rigidly because so and so has one and then learns what freefloat is and does will learn the hard way because AR's are an expensive and unforgiving addiction by spending hundreds of dollars needlessly... the most painful of all lessons learned.

You obviously didnt do your homework and understand what free float rails or even no free float rails are supposed to do.  They were not designed to "hold zero" with a scope so I dont understand what your bitching is about.

Quoted: can you say heavy?

Exactly, strong. My MRP's are heavey too. I just never understood a few ounces mattering when you are installing an rail to strap a few pounds of shit on. Get real. The height is an issue,  especially for acogs, not aimpoints. The SIR does have about half the deflection (the upper half with you optics), than a knight or Larue. The lower half flexes, which is a good thing in my opinion, as it absorbs the shock and keeps your optics more true to the bore. A rail mounted front sight on a KMC rail moves a quarter inch up and down with deflection. How useless is that. But most importantly, as Gunzilla stated, the barrel nut takes all the torque from deflection without the additional attachment point. Finally you are simply not cool enough to post pics on this site if you aren't running a LaRue.

Clippen.

Quoted: Quoted: I was on the phone to KAC to get an RAS I swear , but I felt after my contact I felt that I did not want to be a KAC customer I'll leave it at that, I received an apoplogy here on the boards after all my pissing and moaning from a righteous brother and AR15.com member who works @ KAC and I really appreciated it but by then my $400 had already been spent by the Swans but after much debate regarding the Ras maintaining a zero with an optic on the top rail since it does not freefloat the barrel rigidly I was very glad I got a SIR. Now I am not trying to open a can of worms by stating the RAS can not hold a Zero. But how can any four rail system that is not rigidly mounted in any other fashion than what is designed to hold plastic handguards maintain sight zero? The RASII fixes that but with the cost of lump in the middle of the upper - not a slag just an observation. It seems an expensive option to only be able to attach a light and a VG since the wobble issue will persist regardless of what I think. A newbee who buys a 4rail system which does not mount rigidly because so and so has one and then learns what freefloat is and does will learn the hard way because AR's are an expensive and unforgiving addiction by spending hundreds of dollars needlessly... the most painful of all lessons learned.                 You obviously didnt do your homework and understand what free float rails or even no free float rails are supposed to do.  They were not designed to "hold zero" with a scope so I dont understand what your bitching is about.

Exactly, or a rail mounted front sight.

Quoted: I was on the phone to KAC to get an RAS I swear , but I felt after my contact I felt that I did not want to be a KAC customer I'll leave it at that, I received an apoplogy here on the boards after all my pissing and moaning from a righteous brother and AR15.com member who works @ KAC and I really appreciated it but by then my $400 had already been spent by the Swans but after much debate regarding the Ras maintaining a zero with an optic on the top rail since it does not freefloat the barrel rigidly I was very glad I got a SIR. Now I am not trying to open a can of worms by stating the RAS can not hold a Zero. But how can any four rail system that is not rigidly mounted in any other fashion than what is designed to hold plastic handguards maintain sight zero? The RASII fixes that but with the cost of lump in the middle of the upper - not a slag just an observation. It seems an expensive option to only be able to attach a light and a VG since the wobble issue will persist regardless of what I think. A newbee who buys a 4rail system which does not mount rigidly because so and so has one and then learns what freefloat is and does will learn the hard way because AR's are an expensive and unforgiving addiction by spending hundreds of dollars needlessly... the most painful of all lessons learned.

For having a sturdy foregrip, the surefire rail I handled was rock solid, non ff is more sturdy.

After having one on my carbine now, I won't go back...Evey AR I own in the future will have one on it...Just my .02 I feel it is that good a system.  As for weight - I'll get my shorts on and go hit the gym until the weight isn't a problem, plus i'm not planning on being invaded any time soon.  So no 'humping' my weapons through any potato fields up here in Northern Maine unless the Minutemen are planning to come and watch along the northern border.
Don

Quoted: Quoted: I was on the phone to KAC to get an RAS I swear , but I felt after my contact I felt that I did not want to be a KAC customer I'll leave it at that, I received an apoplogy here on the boards after all my pissing and moaning from a righteous brother and AR15.com member who works @ KAC and I really appreciated it but by then my $400 had already been spent by the Swans but after much debate regarding the Ras maintaining a zero with an optic on the top rail since it does not freefloat the barrel rigidly I was very glad I got a SIR. Now I am not trying to open a can of worms by stating the RAS can not hold a Zero. But how can any four rail system that is not rigidly mounted in any other fashion than what is designed to hold plastic handguards maintain sight zero? The RASII fixes that but with the cost of lump in the middle of the upper - not a slag just an observation. It seems an expensive option to only be able to attach a light and a VG since the wobble issue will persist regardless of what I think. A newbee who buys a 4rail system which does not mount rigidly because so and so has one and then learns what freefloat is and does will learn the hard way because AR's are an expensive and unforgiving addiction by spending hundreds of dollars needlessly... the most painful of all lessons learned.                 For having a sturdy foregrip, the surefire rail I handled was rock solid, non ff is more sturdy.

i would never trust optics on a surefire rail

Quoted: Quoted: Quoted: I was on the phone to KAC to get an RAS I swear , but I felt after my contact I felt that I did not want to be a KAC customer I'll leave it at that, I received an apoplogy here on the boards after all my pissing and moaning from a righteous brother and AR15.com member who works @ KAC and I really appreciated it but by then my $400 had already been spent by the Swans but after much debate regarding the Ras maintaining a zero with an optic on the top rail since it does not freefloat the barrel rigidly I was very glad I got a SIR. Now I am not trying to open a can of worms by stating the RAS can not hold a Zero. But how can any four rail system that is not rigidly mounted in any other fashion than what is designed to hold plastic handguards maintain sight zero? The RASII fixes that but with the cost of lump in the middle of the upper - not a slag just an observation. It seems an expensive option to only be able to attach a light and a VG since the wobble issue will persist regardless of what I think. A newbee who buys a 4rail system which does not mount rigidly because so and so has one and then learns what freefloat is and does will learn the hard way because AR's are an expensive and unforgiving addiction by spending hundreds of dollars needlessly... the most painful of all lessons learned.                 For having a sturdy foregrip, the surefire rail I handled was rock solid, non ff is more sturdy. i would never trust optics on a surefire rail

What optics do you refer to? BUIS? I don't trust optics on ANY rail other than an MRP, reciever mounted optics only, I agree. However, they are much more rigid than any free float tube on the market. More rigid than the SIR on the lower half.

Quoted: I'll admit the SIR bulks up the front end like no other BUT, I wouldn't have any other rail system on my M4 ( I can call it that since Colt lost ) the thing would be indestructable if it had an aluminum lower HG sure would add weight but WTF 7-8 ounces? Sorry Combat Jack I have had mine on without locktite for 3yrs and nothing has fallen off shot loose or malfunctioned and what is so complicated about it... less complicated than waiting for a gunsmith ? There is just something very sexy about the way the SIR looks ...IMO

When I bought mine, A.R.M.S. included a tube of Loctite with the S.I.R.   I don't know if they always have.

You guys are right I didn't do much homework didn't feel I needed to but I did know what freefloating the barrel was but I cheated I watched other non free float 4 Rail two piece snap in system (as they hit the market) owners complain/ debate the zero/wobble issue on the boards after I bought my SIR. (an RAS was the type of system I really wanted - I did state I called KAC)
 After many threads/debates where the skeptism of mounting an Aimpoint or an Eotech type electronic optics hold a zero on the 12 oclock rail I determined IMHO that the SIR has many inherent advantages based merely on design. I should have specified I mount an Eotech over the barrel not on the receiver rail and also should have mentioned I am aware the Surefire4 rail snap in HG system boasts holding a sight zero thanks to counter tensioning feature but there were/are still plenty of threads about certain brands and the wobble/zero issue. I did not mean I mounted a rifle scope on the 12 oclock rail over the barrel scout style I meant electronic optics sorry 'bout not being specific - should have read my mind LOL.  
 But after puschasing my SIR I didn't see the same complaints with the SIR and essentially it satisfied me to no end that I purchased a SIR #50 bi-level even tho' I wanted an RAS - these 'zero issue' threads took place couple of years ago when the SIR was the major player and just about the only other 4 rail system as readily available was the C-More Quad Rail - remember that lead sled? But other 4 rail systems were emerging. I am aware the RAS was available back then and to reiterate I did call KAC to buy an RAS ?
 Then other outfits started making lighter less expensive 4 rail systems as we are well aware of which snap in the HG cap and delta ring. Which was my observation not a slag as I stated how could they be as rigid as a system as one that mounts to the entire upper receiver ? I guess my point after feeling I ended up with 2nd best with the SIR  it ended up with many more features than I could've suspected and am quite pleased I did not get what I wanted the RAS . The newbee I refer to was purely hypothetical in terms of members on limited funds and the glaze in his eyes when he saw an item he wanted - BAD.  Let he who has not purchased impulsively cast the first - frag !  
MERRY CHRISTMAS Bro's ...it about that time .
- the locktite always came but was for the yoke screws only.        

I like mine just fine.

BAMM. Merry Christmas.

Quoted: BAMM. Merry Christmas. img.photobucket.com/albums/v370/M4-TUNA/DSC00194.jpg

Why don't you try an Vltor stock... I hear they are pretty good.

I regret selling all of mine, especially the #58.

I never like how much flex the forward hand grip had in mine.  

Prior to selling my bi-level, I took all the attachments off and I liked it better than way, but since I bought it to use with a hand grip I went with another hand guard.

This is perhaps the thing that I like the least about this these types of handguards... that barrel nut was never intended to support this load and using it for a handguard mount only makes the barrel/receiver alignment flex more

This is exactly what has bothered me as I assess what system I want to mount on my next two builds.  

I am leaning towards SIR systems for my 16" mid and 20" HBAR projects.  I want to preserve robust construction while gaining improved accuracy.  Weight is secondary as I have lighter rifles if needed.

I have a 46C.  I like it.

toooooo heavy IMHO

Quoted: My MRP's are heavey too. I just never understood a few ounces mattering when you are installing an rail to strap a few pounds of shit on. Get real.

I love statements like this.

BTW, not everyone "straps" pounds of shit on their FF Rails.  

The only items mounted on my FF rails are KAC panels, a sling loop and a light.

Love mine.

Quoted: Quoted: My MRP's are heavey too. I just never understood a few ounces mattering when you are installing an rail to strap a few pounds of shit on. Get real. I love statements like this. BTW, not everyone "straps" pounds of shit on their FF Rails.   The only items mounted on my FF rails are KAC panels, a sling loop and a light.

So why even have a rail system then?  There are much cheaper FF systems available than most rails.

I could really give a rats ass what other people are using on their ARs.  I use what I like, not what is in vogue this month on arfkom.

Rock solid!

will a SIR fit a POF piston upper?

Quoted: will a SIR fit a POF piston upper?

I doubt it.   Look at the ring in front of the barrel nut.  I bet the would cause some headaches.  Not sure if all POF uppers are that way, though.  The SIRS' upper rail is more concave.

Picture courtesy of SMGLee