has any one had the problem of matching the yolk ant he upper rail on their sir civ?  i spent about 2 hours trying to match up the screws, only gtting one in....it seems secure enough. any suggestions?
thanks

ttt

I dont know? I've installed probably a dozen and they all go on fine?

Yeah, mine was a bitch! I think it was because the delta ring was a little tight on the yoke. I beveled the ends of the screws a little and just kept trying and eventually they went in ok.

I have noticed that almost every single pic I see of a C model SIR still has the Delta assembly intact.  Do most guys leave them on just to save the trouble of having to remove the barrel?  I planned to remove mine as well as the handguard ring once I get a SIR.

WAY back when they first came out there was a thread obout some not fitting becuase of the distance of the first rail cut from the front of the receiver.  That was why they guaranteed a fit on Colt and Bushmaster, and siad that while it may fit others, it was not guaranteed.  Some Bushmasters had too long a distance between and needed some fitting.  What make is your upper?

There are two models of SIR's, the -C and -M.

The -C model is designed to fit around the delta ring, so you don't remove it:

[img]http://www.imagestation.com/picture/sraid60/pf36ce2b321ffb6ac7210b763e7bcfdc2/fc404f4e.jpg[/img]

The -M model [b]requires[/b] removal of the delta ring assembly in order for it to fit.


Chris

my upper is a dpms, the distance to the upper seem fine, but its seems like the barrel is to wide on the yolk..the hole seem like they r almost perfect, but onlt one screw goes in....sorrt of a bad design.i would think the screws should be one solid thread. i do have one in and it seems really secure thouogh...im hoping that will be good enough..or else ill have to take it to a gunsmith

I understand that.  I was just wondering why the guys with the C models don't go ahead and remove the unnecessary delta assy and hand guard ring.

I had this problem with my #45 M model on a RRA upper (It wasn't the upper either as it was in spec).

[b]It took me 45 minutes to install the thing- and I am not mechanically retarded so that isn't the reason[/b]

The screws seem to want to thread in at an angle this screws up the thread holes and they WILL NOT GO INTO THE YOKE.

My solution was to thread the screws in from the inside to the outside (to UNF&*# the ID yoke threads) then I really beat the piss out of the Yoke till it was alligned with a rubber mallet and then CAREFULLY THREADED THE SCREWS WITH A Magnetic flat bladed screwdriver that fit the screws PERFECTLY.

It seems to be impossible to mount the screws without a really properly sized screwdriver blade.

[b]If that doesn't work make sure the threads are not screwed up (by doing the above again) and then bevel the screws and try again.

If that doesn't work you have 2 options:

1 give it to a Pro like Pete in NH or MSTN and pay them for the install or

2 Call ARMS and see what they advise (probably send it back and they will fix what is screwed up and return it[/b]

If a manufacturer tells you they only guarantee that a product fits certain mil spec dimentioned receivers, you should believe them. Believe me, unless you have the gov't prints and a QC dept., you will not know if a receiver is to spec or not. All the SIR's are well designed to fit gov't issue weapons and they do, without exception. RRA and DPMS are less expensive weapons as they do not go thru a lot of the things that the others do, cost savingsn ya know. If you can't install something on something the manufacturer says they don't recommend, don't blame the maker, blame the gun maker for not being to mil-spec, and yourself. I have had no problem with any SIR's fitting. I'm sure if you call ARMS they will try to help as they do on any time I have asked for advise.
Good shootin, Jack

I had a bit of trouble securing the yoke to the barrel on my Bushmaster upper because it was a very tight fit on the heavy barrel.  I couldn't get the holes to line up perfectly by following the directions.  The instructions advised tightening the SIR rail to the upper and then installing the yoke.  I just couldn't get the yoke to line up properly this way.  So I removed the locking bar on the SIR rail.  I positioned the yoke properly and then tightened the four screws on it.  I then re-aligned the SIR rail with the upper receiver and it all went together perfectly.

The problem is that the DPMS rail is a fraction higher than a milspec rail and the rail itself is not milspec.  After going through what you went through, I did what Antonio did and managed to get the yoke secured.  My only problem was that I had to use a rubber mallet to drive in the rail cap to be able to secure the three screws on the rail.  Perhaps filing down the teeth a little on the bottom of the barrel nut may work but I would not recommend this unless you know what you are doing.

"RRA and DPMS are less expensive weapons as they do not go thru a lot of the things that the others do, cost savingsn ya know. If you can't install something on something the manufacturer says they don't recommend, don't blame the maker, blame the gun maker for not being to mil-spec"


[b]I don't think that is true at least for RRA (the SIR fit and now my current KAC RAS II fit a lot easier).

The problem is that the Yoke actually is a VERY tight fit to the SIR itself and that makes it hard to get properly ligned up (for the terribly finicky screws they provide).

The RAS II is perfectly aligned and has equidistant free space in relation to the forend cap the whole way around.  I don't think the RRA upper could do this while being out of spec.[/b]

If you take a closer look, the yoke doesn't touch the barrel. The yoke doesn't ride on the teeth, it rides on the barrel nut (mil-spec)housing. I found out that the screws are best installed with the cross bar not fully tightened. Don't tighten any of the yoke screws untill they are first all in partially started, then it's real easy. The SIR is the only system that is in real alighnment with the receiver as it grabs the 4 angles of the receiver, plus for almost the entire length of it, about 5" each side for a total of 10" of grabbing power.  It also has three square cross bars in the clamping bar that go thru the square receiver nothches.  Not the (single) (round) screw in a (square) hole, and only a (half inch) each side like the other one mentioned has.
Good shootin, Jack

 

For me personally, I purchased the -C models I have because of the modification-free installation.  

Also, I wanted to have the option of going back to regular handguards, [i]just in case[/i].


Chris