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Posted: 1/14/2006 12:40:08 PM EDT
I'm looking to replace my KAC FF RAS (rifle length) with a PRI tube. Why you ask?

Well, the first reason is I don't need all of the "rail estate" on the KAC. The only things I used on the rails are a KAC QD sling mount and a Harris bipod on an ARMS #32 mount. Also, the KAC FF RAS is fat in my hand with Tango Down rail panels (this is the panel of my choice) and since I don't use a VFG with this rifle, I would prefer to a slimmer profile than the KAC currently has.

BTW, I've tried KAC rail panels and they're not for me. I also own Daniel Defense and Larue rail systems so I'm initimately familiar with them. For the rifle in question, the PRI seems to be the best option based upon my needs.

I've researched the weight of the PRI rifle length tube in various configurations so I know I can save a few ounces over the KAC FF RAS w/Tango Down rail panels. The only rails I would currently need for the PRI would be a short rail at 9 o'clock for the sling mount and a short rail at 6 o'clock for the bipod.

With that in mind, here are my questions:
- How does the PRI tube's profile compare to a standard handguard or other rail systems with panels?
- Can rails be added to the PRI tube while it is installed on the rifle? I might want to add additional rails for things I might decide to use in the future?

That's it. Thank you for your time.
Link Posted: 1/14/2006 1:14:18 PM EDT
My PRI tubed rifle feels slimmer than my Larue railed guns with Magpul rail panels.

I have installed rails on the muzzle end of the tube while the rifle is assembled, but I am not sure how easy it is to add rails near the magwell end while assembled. The rail "backers" may be tough to get in there and keeping everything aligned would be tough. My tube is the competition one without the heatshield, so that is something else you would have to contend with.

Maybe Zak Smith will chime in. I have seen in the pictures that he has reconfigured his competition gun quite a bit. Don't know if he pulls the tube or not.

I run the PRI rail with the integral sling mount, but it is chunky. One of these days I am going to cut it down like Zak did in that post he has floating around here. I also just use a Harris bipod mounted to a sling stud at 6:00 rather than have another rail mounted there. Keeps it simpler for me.
Link Posted: 1/14/2006 1:28:16 PM EDT
Thank you for the reply rpmwfo. That's all good to hear.

Since I know Zak uses PRI tubes, I searched for posts by him but didn't find them until now. Argh. I didn't remember that he puts a "-" between his first and last name. Hopefully, I will be fortunate enough to see this thread and reply to it.
Link Posted: 1/14/2006 5:33:29 PM EDT
i took the top rail off mine for awhile and then decided to put it back on without removing the FSB....
it was a major pain but it was possible. i had to lay on my back and hold the upper above me, then drop the backing plate into the tube and fish it into place with a dental pick thru the holes, and then gently get the screws started.
i wouldn't recommend it and won't ever do it again but its possible!
Link Posted: 1/14/2006 6:48:33 PM EDT
Without rail covers, it will be thinner. With rail covers on all available rails, which most don't do, it would be really close to a KAC. They are heavy, though. Heavier than a KAC. If slim is a concern, I'd definitely go with a DD or LaRue.
Link Posted: 1/14/2006 6:50:28 PM EDT

Originally Posted By mongo001:
Without rail covers, it will be thinner. With rail covers on all available rails, which most don't do, it would be really close to a KAC. They are heavy, though. Heavier than a KAC. If slim is a concern, I'd definitely go with a DD or LaRue.



wasn't there a post recently about the PRi tubes with the light weight aluminum barrel nut, and only the smallest rails at 12/6 o'clock weighing in under almost any of them? i'll try to find..
Link Posted: 1/14/2006 6:59:39 PM EDT

Originally Posted By chromeluv:

Originally Posted By mongo001:
Without rail covers, it will be thinner. With rail covers on all available rails, which most don't do, it would be really close to a KAC. They are heavy, though. Heavier than a KAC. If slim is a concern, I'd definitely go with a DD or LaRue.



wasn't there a post recently about the PRi tubes with the light weight aluminum barrel nut, and only the smallest rails at 12/6 o'clock weighing in under almost any of them? i'll try to find..



Yep, they are lighter with all rails stripped and an aluminum barrel nut, but why not just go with a straight CF tube then? Then you'd be real light and slim.
Link Posted: 1/14/2006 7:01:10 PM EDT

Originally Posted By mongo001:

Originally Posted By chromeluv:

Originally Posted By mongo001:
Without rail covers, it will be thinner. With rail covers on all available rails, which most don't do, it would be really close to a KAC. They are heavy, though. Heavier than a KAC. If slim is a concern, I'd definitely go with a DD or LaRue.



wasn't there a post recently about the PRi tubes with the light weight aluminum barrel nut, and only the smallest rails at 12/6 o'clock weighing in under almost any of them? i'll try to find..



Yep, they are lighter with all rails stripped and an aluminum barrel nut, but why not just go with a straight CF tube then? Then you'd be real light and slim.



roger that, definitely. Need some property up top and down below for front sight and bipod
Link Posted: 1/14/2006 11:15:15 PM EDT
I would go with the competition PRI tube and add the short rail for the front buis and their integrated QD sling/rail with Zak style chop job. A lot lighter, slimmer and cheaper than a rail + rail covers. MSTN has them. I think the 12" competition tube without rails weighs 10-11 oz.

Now if you ever plan on going with more rails, I would go Larue. Less parts and pieces to come loose.
Link Posted: 1/15/2006 8:07:50 AM EDT
[Last Edit: 1/15/2006 8:10:53 AM EDT by Matt_B]

Originally Posted By mongo001:
Without rail covers, it will be thinner. With rail covers on all available rails, which most don't do, it would be really close to a KAC. They are heavy, though. Heavier than a KAC. If slim is a concern, I'd definitely go with a DD or LaRue.

I've got DD and Larue rails on my other ARs. I like the profile of the DD w/KAC covers but I prefer the TD covers over the KAC. Since 95% of the rails on my 20" AR are unused, I would like to simplify things by only having the rails I need.

Regarding the weights, here's what I dug up from the Archive (these are straight from PRI):

PRI rifle free float fore with all rails, steel nut 1.19Lbs (19.04 oz.)
PRI free float forearm with steel nut, no rails .855 lb. (13.68 oz.)
PRI rifle free float forearm with aluminum nut, no rails .700 lb. (11.20 oz.)
PRI rifle length, all rails and aluminum nut 1.015 lbs. (16.2 oz.)


The KAC rifle FF RAS weighs in at 16.2 oz. without any panels. I haven't taken the time to weigh tall he TD panels on my rifle but if an 11 rib KAC panel weighs 0.9 oz. then the TD panels add the very least 5.4 oz which brings the KAC rifle FF RAS to at least 21.6 oz. A PRI rifle FF tube with aluminum nut and 2 short rails (for sling mount and bipod) is probably going to weight 1 lb. or slightly less.

So needless to say, I'm not worried about the PRI weighing more in the configuration I plan on using.

I should also mention that the rifle this will go on already has a PRI front sight so I won't need any rails on top for anything.

I was going to go for a Larue rail system on this rifle but, after considering how few rails I really need, I'm leaning towards the PRI tube for simplicity's sake.
Link Posted: 1/15/2006 10:43:10 AM EDT
I visited PRI's website and checked out the Target Forearm but I can't tell from the picture if that forearm has pre-drilled holes for rails. I'm not too concerned about the lack of heatshields because I always wear gloves when I shoot. I also don't care about the natural finish because I will get it finished in OD green whe I get it.

I sent an e-mail to PRI to see if this forearm has holes for mounting rails. If not, they should probably be easy to add.
Link Posted: 1/15/2006 1:40:12 PM EDT
The competition forearm has the pre-drilled holes for rails. It doesn't have heatshields, and it comes with the aluminum barrel nut.
Link Posted: 1/15/2006 2:19:41 PM EDT

Originally Posted By rpmwfo:
The competition forearm has the pre-drilled holes for rails. It doesn't have heatshields, and it comes with the aluminum barrel nut.

Roger, I got that when I was researching them. Thank you for the confirmation on the holes though.
Link Posted: 1/15/2006 7:29:57 PM EDT
[Last Edit: 1/15/2006 7:41:53 PM EDT by Onslaught]

Originally Posted By rpmwfo:
The competition forearm has the pre-drilled holes for rails. It doesn't have heatshields, and it comes with the aluminum barrel nut.


So how does that work? You just purchase the rails you need and the go right on? Is it basically the standard PRI tube without a heat shield or rails? (appearance et.al)

Man did I need to find that out! I'm with MattB on this as far as the PRI tube goes. I don't need a heat shield for what I'm working on, and all I need is a couple of short rails for a front sight and a bipod.

MattB, if you get confirmation from PRI about the rails, please post it. I can't drill a straight hole to save my life, so drilling my own is out of the question

THANKS for the post!
Edited to add:



Well, I don't see any rail mounting holes, but I suppose I could get someone qualified to use power tools and sharp objects to drill me a couple. At least it's still indexible, which is a big help.
Link Posted: 1/16/2006 4:49:57 AM EDT
Link Posted: 1/16/2006 5:13:40 AM EDT
Thank you for the reply Wes. I would prefer to mount the bipod with the ARMS #32 on a short rail just for convenience's sake. MSTN is of course on the short list of vendors I would purchase it from and install it for me. Besides, you guys, specifically Paul, put the upper together in the first place for me.
Link Posted: 1/16/2006 5:28:32 AM EDT
Tag
Link Posted: 1/16/2006 9:26:29 AM EDT
Link Posted: 1/16/2006 10:42:54 AM EDT
.
Link Posted: 1/16/2006 5:56:42 PM EDT
How much $
Link Posted: 1/16/2006 5:58:21 PM EDT

Originally Posted By zdenstk:
How much $

Around $250 to $320, depending up on configuration. MSTN and ADCO, who are both sponsors of this site, sell them.
Link Posted: 1/17/2006 3:34:38 AM EDT

Originally Posted By gunslingerdoc:

Also remember that if youre going to drill a hole in carbon fiber, use a sharp drill bit and drill thru some tape to cut down on splintering of the fibers.

Hope that helps....



Also, drilled holes can be sealed to protect the broken fibers by wicking in some simple enamal paint.
Hope that helps as well.

BTW;
I posted, a ways down now, Wanting to know the exact outside diameter of these PRI tubes and have not gotten a reply.
Anyone want to help me out with this dimension?
Link Posted: 1/17/2006 7:55:43 AM EDT
Link Posted: 1/17/2006 8:04:58 AM EDT

Originally Posted By MSTN:
2.00".

Excellent. Thank you Wes. Althought I don't recall the exact numbers for the Larue or DD, that makes the PRI slightly smaller than either of them.
Link Posted: 1/17/2006 11:14:56 AM EDT
Good choice on the PRI. How much for the KAC FF RAS? Dibs?
Link Posted: 1/17/2006 11:25:42 AM EDT

Originally Posted By mleaky:
Good choice on the PRI. How much for the KAC FF RAS? Dibs?

I'm afraid you'll have to take number at this point. If you are interested, send me an IM and I will contact you if the other person does not buy it.

Also, I just ordered an optic today and changed the FF tube on the rifle in question is not a pressing matter. I expect to do it in the next couple of months.
Link Posted: 1/17/2006 12:33:46 PM EDT
Have you considered the DD rail? It will weigh right at 16oz with 3 TD rail covers on it. 13.1 + .9 X 3 = 15.8 oz and you dont have to worry about adding additiononal rails in the future should you buy NV and need a laser or something. DD are the slimmest traditional rail system you can get as well. Just another option to consider.
Link Posted: 1/17/2006 2:41:12 PM EDT
Thanks for the input DevL. I actually have a DD rail system on an AR and while I do like the slimmer profile of it (it currently has KAC covers on it), I'm looking to get away from having any rails I don't need at all. As silly as it may sound, empty rails need covers (at least for me) and covers are one more thing to deal. I'm trying to make things super simple this time around.

Even then, as much as like the DD rail, if was to get another full blown rail system, I would get another Larue because I like the locking tab. I have had 2 rail systems get loose just once (both were professionally installed by people who had installed 100s if not 1000s of them) and that convinced me that the locking tab is a nice little piece of insurance.

Now that I've gotten my 16" optic arrangement out of the way, I can put all my brain's cycles into deciding what to do with my 20" AR's handguard.
Link Posted: 1/17/2006 5:51:08 PM EDT
Might I also point out that both Viking Tactics and D&L Sports offer a tubular forend sans all the rail estate. You don't hear a lot about their wares, and I don't know why.

Still, it's good to know there are options.
Link Posted: 1/17/2006 5:59:47 PM EDT

Originally Posted By VaughnT:
Might I also point out that both Viking Tactics and D&L Sports offer a tubular forend sans all the rail estate. You don't hear a lot about their wares, and I don't know why. Still, it's good to know there are options.

Thank you for bringing those up VaughnT. Unfortunately, both of the tubes offered by those companies are aluminum and I am looking at carbon fiber tubes due to the fact the the PRI tube does not get as hot as a standard aluminum handguard.

For whatever reason, their rail systems are not well known so in turn not that many people (at least the ones that post here) don't use them and my days of being a guinea pig are long past. At this stage in my life, I want to buy products that I know have been proven in the field and have a lot of positive customer feedback. Please understand that I have no reason to dislike any of the products from those manufacturers. It's just that I am not a gambling man when it comes to my gun gear.
Link Posted: 1/26/2006 11:30:07 AM EDT
Do you guys think the carbon fiber is tough enough to attach a sling stud right to it without a rail? I'm looking at getting one and though it would just be simpler to do it that way, but I'd still like to use the sling to steady it and don't want to rip it out or something.....
Link Posted: 1/26/2006 12:37:29 PM EDT

Originally Posted By RolandofGilead:
Do you guys think the carbon fiber is tough enough to attach a sling stud right to it without a rail? I'm looking at getting one and though it would just be simpler to do it that way, but I'd still like to use the sling to steady it and don't want to rip it out or something.....



If you go with the PRI tube, there are several options:

1. Remove an existing rail and replace with sling swivel studs. The PRI tube uses metal plates under the carbon fiber to secure the rails to the tube. They wisely, or coincidentally, threaded these the same as a swivel stud so a pair of studs can replace the rail. I replaced my lower rail with 2 swivel studs so I can attach a Harris bipod and a shooting sling. Doing this saved me the combined weight of a rail and a bipod adapter.

2. Drill and tap the end of a rail section and attach a swivel stud. PRI sells accessory rails with this feature already on them, but it is not hard to do yourself. I did this on my left side rail to attach a 3 point sling.
Link Posted: 1/26/2006 2:13:25 PM EDT
Thanks,
so if I order the target tube, there won't be any metal to screw the studs into though right?
Link Posted: 1/26/2006 2:52:07 PM EDT

Originally Posted By RolandofGilead:
Thanks,
so if I order the target tube, there won't be any metal to screw the studs into though right?



I'm pretty sure that they don't include any metal to screw into, although you could just use a standard nut. Even more important is that they don't, AFAIK, have any holes to place the studs through. Here is a picture from their website, and it does not show any predrilled holes.

http://www.pri-mounts.com/mm5/graphics/images/05-074-03.jpg

I prefer the flexibility that the standard tube provides.
Link Posted: 1/26/2006 3:38:17 PM EDT
Well, I'll figure something out. The standard tube is heavier than what I want (target tube is like 10oz or something) and I have a killer deal in the works for a target tube so the standard isn't worth the extra $ for me.....thanks
Link Posted: 1/26/2006 3:50:26 PM EDT
Link Posted: 1/26/2006 6:03:44 PM EDT
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