My Centurion Arms Hand Guard today.

AR/M4 AR Technical Discussion
1

I went with the C4 Carbine Cutout Rail. I was wondering if there was any specific torque spec’s for the screws? I have an inch lbs. torque wrench and some small allen sockets, at least to tighten the four larger screws. Centurion Arms seems to be having trouble with there web site so I can’t find any info there. Or should I just tighten them to where they seem to be go to go?

Thanks in advance, NYH1.

2

I don’t believe there is an official torque spec. The C4’s use helicoil inserts, so locktite isn’t needed either unless you really want to use some.

I once read on the mighty internet that people like 15-20 inch pounds as they compare the screws to those on scope rails.

3

I have always just snugged them up hand tight without getting too over zealous, has worked fine.

4

Same here, hand tighten them evenly watching the rails position in relation to the upper, then snug them up tight by hand without too much force.

5

There are are torque charts that you can Google that will tell you the proper torque of screws and bolts. Varies by size, threads per inch, material, and if the screw is tightened dry or with lube or threadlocker. You’d be surprised how little torque is needed on small fasteners. Start there and if it doesn’t loosen, you’re good to go. You can always increase it by a little bit if needed.

6

I have the C4 Installation Instructions in a PDF file. Shoot me an email and I’ll send them if you want.

7

I’m sure around 40 would work. Most can take upwards of 80, if you think about it, thats really leaning on the thing.

I’ve never used a TQ wrench with any build, I just time them as recommended and the final timing is the last “torquing”

8

I wrote the installation instructions and there is no torque value for those screws. They use helicoil inserts and you should not be using Loctite with them. Make sure that the rail is properly aligned and tighten the screws down until they are snug.

9

Thanks for all the replies guys, I really appreciate it!

I have to say, I’m not really a “rail guy”…but this one is GREAT! One of my favorite hand guards is the older smaller diameter CAR hand guards. Bought my first AR back in '02, it was a RRA Tasc Rifle middy. I let that one go a few years after I bought it. But I kind of liked the extra length of the middy. Obviously it wasn’t a determining factor for any of my future AR’s.

But when I saw a picture of a carbine with a C4 Carbine Cutout Rail on it…I had to have one! I knew it would give me a little bit more room/length and I could mount my Surefire G2X Tactical Light and anything else I want on it. I think I’m going to get this Magpul Rail Light Mount. Cheap, easy, mounts the light high up at the 11 o’clock position in front of my front sight. I ride my thumb on/along the IWC mount on the similar setup I just replaced.

Thanks again, NYH1!

10

Thank you for this post! I was unaware of the helicoil inserts. I have used blue Loctite on all the Cr rails that I have installed… :o Is this a problem with the helicoil inserts, or a non-issue? I mean… should I go remove all the screws from these C4 rails and remove the Loctite at this point, or just leave it?

I’m talking about 4 C4 rails that I have them installed for between about 2 years to the last month on the latest one…

Thank you in advance for your input.