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Posted: 4/7/2009 3:58:41 PM EST
First post on here, please be gentle .

I have a set of KAC rails and I see that they don't fit. Has anyone been able to mill their rails to fit a heavy barrel? I have a Bushie with the 16" heavy barrel and the rails just won't fit near the receiver end. Since I have never built or worked on an AR I am hoping that there are some experts out there that can guide me. Yes, I am very familiar with the M4 system, but that goes only along the lines of using it...OIF and OEF, never in an armorer mode. Thanks in advance!
Link Posted: 4/7/2009 4:06:34 PM EST
which rail?

The RAS will NOT fit *heavy* barrels

The RIS will..
Link Posted: 4/7/2009 4:12:04 PM EST
Sorry, I have the RAS, the lower part fits fine, it's the upper that just will not get in by a slight margin. I've read an old post on a different site where the guy milled his rail t fit the heavy barrel. I was seeing if anyone has ever done so and what procedures they went through.
Link Posted: 4/7/2009 4:41:36 PM EST
[Last Edit: 4/7/2009 4:42:34 PM EST by exocet]
you can probably remove the front part by pushing the pin out. It should fit after that.
I did that on a Bushmaster HBAR barrel.
Link Posted: 4/7/2009 5:12:26 PM EST
all I ever tried fit


what brand barrel is it?
Link Posted: 4/7/2009 5:14:04 PM EST
Originally Posted By chromeluv:
which rail?

The RAS will NOT fit *heavy* barrels

The RIS will..


not true i have seen some RAS that will fit the HB, OP is prolly hanging the mount up somewhere on the delta ring. First couple times trying to put the RAS on can be kinda rough.
Link Posted: 4/7/2009 5:14:05 PM EST
[Last Edit: 4/7/2009 5:14:28 PM EST by renesis]
Double tap 2.0
Link Posted: 4/7/2009 5:14:43 PM EST
haha double tap!!
Link Posted: 4/7/2009 5:21:01 PM EST
[Last Edit: 4/7/2009 5:58:54 PM EST by Kyarguy]
So will a KAC M5 fit a 20" Rock River Arms heavy barrel??

ETA: Barrel Brand

KyARGuy
Link Posted: 4/7/2009 5:34:31 PM EST
My KAC Ras would not fit on my Olympic Arms heavy barrel without a little help from the Dremel. It took me about 5 minutes of removing material and test fitting to get it to work.
Link Posted: 4/7/2009 5:40:48 PM EST
Same here, the RAS wouldn't fit my olympic heavy barrel. I didn't really want a heavy barrel anyways, so I sold the Olympic and got a Del-Ton lightweight kit.
Link Posted: 4/7/2009 5:45:30 PM EST
Thanks for the replies..

1. it's a Bushmaster 16" heavy barrel 5.56mm
2. Exocet, what part are you talking about?
3. Renesis, you are right that I am getting the hangup near the delta ring.
4. grapenutsrobot, what area are you using the dremel on?
5. Shawnmt6601, same as I mentioned for number 1, HBAR 16" bushmaster.

Like I mentioned, it's just right at the delta ring where it just does not sit, I am talking just a bit.

Thanks for all your inputs, looks like I found a great site!!
Link Posted: 4/7/2009 6:07:09 PM EST
The issue usually involves the rear locking "tongue" on the upper rail not going under the barrel not and therefore preventing the the front of the rail from clearing the end-cap. Remove the screw that tightens the tongue and then try installing, watching for the tongue to slip under the the lip of the barrel nut. Once in place, reinstall the screw. I've installed the RAS on three different 16" Colt barrels this way.


Link Posted: 4/7/2009 6:09:05 PM EST
Originally Posted By Kyarguy:
So will a KAC M5 fit a 20" Rock River Arms heavy barrel??

ETA: Barrel Brand

KyARGuy





yes
Link Posted: 4/7/2009 6:11:23 PM EST
Originally Posted By Molon:
The issue usually involves the rear locking "tongue" on the upper rail not going under the barrel not and therefore preventing the the front of the rail from clearing the end-cap. Remove the screw that tightens the tongue and then try installing, watching for the tongue to slip under the the lip of the barrel nut. Once in place, reinstall the screw. I've installed the RAS on three different 16" Colt barrels this way.


http://www.box.net/shared/static/yuhhx1nzgq.jpg




I was just about to post that.


Make sure the silver metal hook is going under the barrel nut (between the barrel nut and barrel). If its not you wont be getting the rail on. Its best to angle the barrel down at about a 45 degree angle so it swings down, and then try to snap the back part of the top rail under the delta ring. Then put the screw in, and hand tighten.

IIRC usually if the RAS wont fit an HBAR its towards the front not the back.
Link Posted: 4/7/2009 6:12:33 PM EST
Originally Posted By suasponte2:
Thanks for the replies..

1. it's a Bushmaster 16" heavy barrel 5.56mm
2. Exocet, what part are you talking about?
3. Renesis, you are right that I am getting the hangup near the delta ring.
4. grapenutsrobot, what area are you using the dremel on?
5. Shawnmt6601, same as I mentioned for number 1, HBAR 16" bushmaster.

Like I mentioned, it's just right at the delta ring where it just does not sit, I am talking just a bit.

Thanks for all your inputs, looks like I found a great site!!









dont go cutting yet


man, when they are new, they are a bitch. it took me 45 minutes to wiggle one on a colt HBAR. but they will fot. I got a KAC raisl on 6721s, a colt 20 inch HBAR
a stag HBAR and a RRA HBAR

they are tight and if you dont watch the clamp it will not lock up under the nut just right and it looks like it wont fit. just keep trying. take out the screw and put an allen wrench in the hole to keep the hook in the down postion
Link Posted: 4/7/2009 6:50:35 PM EST
[Last Edit: 4/7/2009 6:52:31 PM EST by grapenutsrobot]
The issue with my barrel had nothing to do with the rear of the RAS. I have had a RAS on my issue weapon since 2002 , and I know how to install it. The front portion on either side of the gas tube cut out was a different contour than my barrel and would not allow it to seat. I had to expand the contour little by little until it was the same as my barrel. My RAS was made in 2007 so this part may be different throughout the years, since I have nothing to compare it to. I f anyone wants a picture of where I removed material, let me know and I'll post it tomorrow.
Link Posted: 4/8/2009 1:28:56 PM EST
Thanks for help. It was easy to install once I removed the tightening screw, push down on the locking lever, and the top piece fit right in. No need to exchange now that it has a great fit.
Link Posted: 6/17/2009 2:54:36 PM EST
Hello all I'm new and I have come across this issue as well. I have an Olympic Arms rifle with an HBAR.

Is it best to install the RIS system or to modify the RAS to fit the HBAR?
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