PDA

View Full Version : Well...bummer



gatordev
18 November 2015, 13:43
Thought this was going to be a fun and quick build, but alas... First up, the mock up:

http://i840.photobucket.com/albums/zz322/gatordev/Public%20pics/Joe%20Bob%20300/IMG_0535_zpsnjfyhs7b.jpg

I have a 7" Centurion Arms rail just waiting to go on this, but it looks like the billet upper interferes with the anti-rotation tabs:

http://i840.photobucket.com/albums/zz322/gatordev/Public%20pics/Joe%20Bob%20300/FullSizeRender1_zpspnq8gxnh.jpg

Here you can see where one of the tabs is wearing on the receiver:

http://i840.photobucket.com/albums/zz322/gatordev/Public%20pics/Joe%20Bob%20300/FullSizeRender2_zpso25rkisp.jpg

Other than the barrel and barrel nut, I had all the parts already, so I was hoping to just throw this together, however now I'm worried I'm going to have to invest in a different rail, which makes this become more expensive than I hoped.

Other than grinding down the rail, any ideas on how to fix this? I'm not too keen on doing any metal work on the receiver, either. I'm not even really sure what to look for in a new rail to make sure the same thing doesn't happen.

Joelski
18 November 2015, 13:57
That sucks, man. No matter how cool it looks, if it ain't spec, forget it. A midwest rail would fit and not break the bank (again) like that CAA rail. Personally, I'd sack the non-standard upper. Good luck!

gatordev
18 November 2015, 15:00
Hmm...I'll have to look at MI.

The story behind the upper (and lower) is a little more complicated. I'd prefer not to just ditch it, lest the wrath of Stick strike.

Also, just for the sake of satisfying my OCD... Centurion Arms most definitely is NOT Command Arms Accessories (CAA). I don't think that's what you meant, but I'd hate for the Google machine to record the error!

UWone77
18 November 2015, 16:05
Ran into the same issue when I tried to swap out handguards on an older Mega Arms Billet upper. Couldn't bring myself to cut off the tabs.

cjd3
18 November 2015, 16:50
Just how often do billet uppers like this interfere with anti-rotation tabs?

Tyrannosaur
18 November 2015, 16:51
Happened to me with a Lantac UAR and that same rail....

Dstrbdmedic167
18 November 2015, 17:05
Just how often do billet uppers like this interfere with anti-rotation tabs?

Quite often unfortunately...

gatordev
18 November 2015, 17:11
Booooo!

Looking at the MI Gen 2 T-series, it looks like the tabs lock into the included barrel nut, and doesn't go far enough back into the receiver. Anyone see any issues with that? It's interesting to see how much harder it's becoming to get quad rails that don't break the bank and don't weigh the equivalent to a RIS II.

Dstrbdmedic167
18 November 2015, 17:16
Not to derail but I assume quad rails that use a standard but are the only thing of interest to you? Fortis makes a great rail that uses a standard nut and works with good amount of billet uppers. Just curious?

gatordev
18 November 2015, 17:30
Don't care about the nut other than it not interfering with the upper, but I prefer a lightweight quad rail for this because a) it's light and b) then I don't have to spend more money on some sort of hand stop that's compatible with whatever the attachment mount that's on the rail (though M-Lok has started to win me over after seeing what these (https://kineticdg.com/) guys are doing). I've got a bunch of Larue hand stops stashed away, so sliding one of those on a quad rail solves a problem and doesn't require yet another "thing" to buy.

UWone77
18 November 2015, 18:27
Just how often do billet uppers like this interfere with anti-rotation tabs?

Newer uppers have cut outs. Like the Mega, now has a cutout on a revision.

Former11B
18 November 2015, 18:47
I was concerned the Anti rotation tabs on my Rainier/Samson rail I ordered several years ago would conflict with the kill switch on my WAR upper. Fortunately, no issues


Can you remove a tiny bit of material from the inside of the tabs so they'll fit around the upper without cutting them completely?

gatordev
19 November 2015, 04:08
Can you remove a tiny bit of material from the inside of the tabs so they'll fit around the upper without cutting them completely?

It's kind of tough to tell (I need to get in there with a flash light), but it looks like the tabs would still hit the "shoulder" of the receiver right below where you see the wear mark. The receiver bows out some and I think the bow is slightly wider than the tab ID. But it's worth looking at again.

I may just grab the MI rail and call it good, though. Since the DD MK18 rail is 9.25" and works on a 10.3" barrel, by my math, I believe the MI 9" rail will work on this 10.5" barrel and still give me access to thread on a can.

Pyzik
19 November 2015, 05:07
It's kind of tough to tell (I need to get in there with a flash light), but it looks like the tabs would still hit the "shoulder" of the receiver right below where you see the wear mark. The receiver bows out some and I think the bow is slightly wider than the tab ID. But it's worth looking at again.

I may just grab the MI rail and call it good, though. Since the DD MK18 rail is 9.25" and works on a 10.3" barrel, by my math, I believe the MI 9" rail will work on this 10.5" barrel and still give me access to thread on a can.

I say mod the rail and touch up the marks with a little paint and call it a day. It won't take much to remove a little material from the tabs, they are aluminum afterall.

Former11B
19 November 2015, 07:14
It's kind of tough to tell (I need to get in there with a flash light), but it looks like the tabs would still hit the "shoulder" of the receiver right below where you see the wear mark. The receiver bows out some and I think the bow is slightly wider than the tab ID. But it's worth looking at again.

I may just grab the MI rail and call it good, though. Since the DD MK18 rail is 9.25" and works on a 10.3" barrel, by my math, I believe the MI 9" rail will work on this 10.5" barrel and still give me access to thread on a can.

I have a 17.5" rail and an 18" barrel and its real close lol

http://img.photobucket.com/albums/v74/DownSouthTAS/Mobile%20Uploads/image_zpsdvklplw5.jpg

gatordev
19 November 2015, 17:47
I say mod the rail and touch up the marks with a little paint and call it a day. It won't take much to remove a little material from the tabs, they are aluminum afterall.

It doesn't look like that will work. Or it's just more than I want to remove, personally. Sure enough the tabs are impacting the shoulder of the receiver. The tabs actually sit lower than the mark in my picture, so a lot more of the rail needs to be removed (at the tabs). Oh well.