Looking to do two things:

1.  Create a sturdier platform with my Knight's FF RAS, similiar to a PRI/ARMS setup.

2.  Add the extra height to the receiver, so when mounting a TA31 series ACOG on an ARMS #19 and hopefully a SPR rail, the objective's height over the bore will be closer to the height the BDC was design for (carry handle mounting).

So, did this combo ever exist?

TIA

It will if you created it!

Seriously, I have been thinking about that lately.  Why not just leave it at the FF RAS?  I mean it is light weight, you aren't mounting optics on it, and you really don't *need* the extra height for the ACOG to work.  Check out the ACOG BDC thread in the optics board, height matters very little.

Yeah, I wish I had the money to build one gun, let alone all the combos I can thing off.  College is expensive.  Better get one now before I get done with community college and go to the 4 year to finish.  Lot more living expenses than w/mom & dad.

I think theoreticaly the ARMS-SPR rail should fit on the FF-RAS rail, but the forend nut might be a problem. The only SPR rail that might fit is the 3rd gen SPR rail, cause it has a cut for the PRI forend nut, wherease previous generations did not. Also the 3rd gen is a tip off rail, but the previous ones are slide on, so again on that count alone you could not get pre 3rd gen to clear the forend nut.

[Edited] Just reviewed an e-mail, the supplier states that the SPR rail fits the PRI setup but not the KAC forends.

223Rem
I have done this on mine, Im not sure of the exact measurements but..... I purchased an M5 RAS at an excellant price a couple weeks ago, I have a Trijicon TA11D (for carry handle) on top of an ARMS#38EX swan sleeve, In a 19S mount, THis raises the sight to what feels to me Is very close to having it on top of the carry handle,But not quite, Im sure Its at least half the distance, Anyway this weekend I was out of state at a friends and he has a 500yrd range at his farm. As close as I could tell the Ranging ret. was dead on. Shooting 500 is WAY out there belive me But I had NO problem putting rounds On Target with this set up on Sillouette size targets, NONE what-so-ever. I was going to get a free Float tube RAS At one point then lucked into the M5 RAS, Im getting Sub Min of angle with an Armalite Factory Barrel on this baby at 100yrds, so I dont think Ill worry about the free float either. At 400 yards I was able to get 5 rounds into about 3 1/4 inch using Black Hills 68gr BTHPs, 62grSS109 was about 4.5" at 400yrds. That was all I had time for, but Im very happy try that set up.
good luck
chuck

The rail will not clear the barrel nut on the KAC RAS.  The version that clear the PRI rail will not fit the barrel nut profile on the KAC.

Chuck,

Why do you prefer the M5 RAS over the FFRAS?  It seems that the FFRAS has all the advantages of the M5.  It is just as stable, if not more so, and free floats the barrel so that the changing weight from mounting various accessories to the rails does not affect the accuracy of the rifle.  Also is the M4 RAS the same as the M5, just in shorter/carbine length?

thelastgunslinger
I really dont know if I like the M5RAS over the FFRAS, Ive never had the FFRAS, I was going to buy one until I got this amazing deal on the M5RAS on ebay. I know everyone is into free floating tubes on these rifles and Im not argueing the benefits at all. But I have an Armalite AR10A4 that shoots Sub-MOA with standard hand gaurds and a harris bipod, I tried for about a year (3years ago)to find a way to free float the barrel, but everyone Including Rick At Armalite said that if a rifle shoots that good why change it. I just put this rifle together and with this set up it shoots the same way, so Ill just leave well enough alone, if it shoots it shoots no matter what Bells and Whistles you have.
Yes I believe the M4 RAS is the Same as the M5 except Length.
chuck  

Thanks for the input gentlemen, but I still think the full length rail would be a benefit for system integrity and durabitly versus weight increase.

May just end up switching the Knight's platform to the 18" SPR w/ Leupold M1 3.5-10X40 (similiar to the MOD 1) and put the ACOG on the PRI/ARMS SPR w/ a Bushmaster 20" Fluted Hbar.  The height over bore and barrel length are more in tune to the BDC of the ACOG.  

eaglecp, how is the leg?

Much better bro, thanks for asking, I think Ill be back to the range in the next week or so.
thanks
cp