Hello again everyone, I posted about flip up vs fixed sights a couple months ago and got some awesome advice so I have another couple questions for you all. I was planning on getting the BCM KMR 13" with a Daniel Defense fixed front sight for my Spikes Carbine and really like the look and weight of it... But then I saw a Centurion C4 Carbine Cut Out... I have a Magpul MOE SL handguard on it now and while I love the hand position on it, the light mounting options are very limited and not to my liking. Plus I'm used to quad rails and their additional width fills my large hands better, the SL feels too small for me. So my post is a two part question.

One: how does the KMR and/or Centurion C4 rails stand up to use? Aka those who have beat them up in carbine courses or use them on patrol rifles?

Two: Being that both require different FSB's, which would be better for a SHTF/possible patrol rifle? I don't see the KMR flexing much to throw the Daniel front sight off but I know the standard pinned FSB attached to the barrel is trusted by many for it's durability and reliability. Am I thinking too much on this?

Thanks again and sorry if I'm asking stupid questions. I unfortunately don't know anyone around me that could let me play with either set up in person. I haven't even seen a C4 rail in person before but I've read nothing but great things.

I have a few C4s, and I would consider them nearly bomb-proof for the rail itself.  It mounts on the standard nut, and I had my concerns until my buddy dropped his on a concrete block one day, and it never moved on the nut.  Something like the Daniel Defense RIS with a proprietary nut would be more solid, just due to the way it's mounted.

I do not have a KMR, but have shot a few rifles with them.  They are ultra lightweight.  There are many KMR owners here, and they will chime in as to its durability.  The mounting is certainly solid, to be sure.

Good luck!

The C4 is an excellent rail.

In my opinion it's the best bang for the buck, and very easy to install.

Love my 10".

Topic Moved

+1 Mine have been great.

Dupe

Ok, thank you for the replies! Are there any KMR owners that want to chime in? I'd really appreciate it!

I have both.  I like things about each.  You can flip a coin and be happy with either one.


Things I like about my KMR:

• It is very light and very thin.


• I don't run panels on it, and I find the key holes make for a good, grippy surface without being too abrasive.


• I mount stuff on, tighten it down, and forget it.

Things I like about my C4 guns:

• More conventional rail configuration that you can bolt more stuff to without having to carry around rail segments or find accessories with the appropriate KeyMod mount.


• Much easier to put on and take off stuff for assorted purposes.  Need a bipod or a flashlight for a course of fire, but don't want to carry it around for the next four stages?  Much easier with the C4


• Plenty of real estate for bolting stuff on in whatever position you want it.


• Fixed front site I don't have to remember to deploy or worry about falling off.

One is not ostensibly 'better' than the other.  As the KeyMod concept becomes more of an industry standard and more purpose-built accessories come on line for it, I can see it becoming the new standard because it is lighter, more compact, and allows for more flexible positioning of accessories.  However, I don't see the death of Picatinny any time soon.  If you want newer, lighter, and what the cool kids have, go with the KMR.  If you want something to fill those larger hands, or if you plan on swapping a lot of Picatinny based accessories back and forth, go with the C4.

I have a C4 and fucking love it. I chose to shave my FSB and go with a longer rail but that's just personal preference as that rifle is a bench gun and I wasn't too worried about weight
 

Very nice looking rifles you have there JohnnyEgo. You brought up a few good points about the picatinny rails. I realistically won't run anything more than a light and possibly the BCM KAG. That's all I need so the KMR would be slick and the C4 would be covered with ladder covers. I'm trying to keep my rifle as simple as possible. Thank you all for the opinions, seems the Centurion C4 rails are thought of very highly here. Keep the responses coming please! The more opinions, the better!

I've had or still most every rail made from most major manufacturers and the KMR is at present the rail to beat.
Lockup & wt were the deciding factors for me....

I think I'm leaning towards the KMR now due to it keeping the weight of my ST-15 more balanced with the govt profile barrel. Have you or anyone else had issues with durability of the rail after any form of abuse in classes or such? I'm not worried about the known finish problem as I'll have it Cerakoted along with my AR later on. I just want to know if the aluminum/magnisium blend is as strong as BCM claims it to be or not. I have also learned about the Daniel Defense SLiM rail and liking it also, just like everything else Daniel makes... I just like the KMR weight more. I have a hard time trusting anything but the 6061-T6 aluminum for rail systems and I'm planning on eventually making this my patrol rifle once it's completed... Tax season is coming and my wife is feeling generous!

Thanks Stickman! Off topic but I love your work! Like talking to a celebrity in the gun industry. Lol. Stick, have you ever ran the KMR hard at all to see how it holds up to abuse being banged around?

So far, i have found other parts of my rifle (charging handle, buttstock, grip, weaponlight) seem to be showing "character", but have yet to ding up the kmr. Another benefit of a front flip up sight on a longer rail vs. the standard front sight post is a longer and more accurate sight radius.