Does anyone know where I can get a low profile pinned gas block that will replace a standard Front Sight Base. It needs to fit under a rail (Daniel Defense, Larue, etc.). The only ones I have seen are all set screw or clamp on type. I don’t trust anything other than a true pinned gas block, because I have seen several set screw gas blocks come loose. Thank you for your help.
None would work. They’d have to offer several variations of the same thing. When barrels are made the FSB and barrel are drilled for the pins. So the exact locations of the pins varies from manufacturer to manufactures and varies even from the same manufacturer.
I apologize in advance for the hijack.
Rob, on my 10.3" that you have seen, I am interested in the DD Omega 9.0 and removing the FSB and going to flip-ups.
Can you simply replace the FSB with a Lo-Pro Gas-Block, or would you have to grind down the FSB as it is already pinned for that Colt barrel and can’t be replaced?
Also, would DD Omega work in this configuration?
Thanks,
Tyler
I do the ‘shave’ of the FSB to make them fit under rails. All three of my SBRs have ‘shaved’ FSB and are held on by the factory/OEM 2 pins. A lo-pro gas block can be used instead and then drilled and pinned but it costs more. An Omega rail has very little room under it. I have done one like that for a fellow M4C member but it’s not going to be easy to ever remove the ‘shaved’ FSB because I had to grind the pins down so everything is flush.
I had to ‘shave’ it while it was still attached to the barrel because it’s a CMMG 14.7" barrel with a perm. attached A2 flash hider. It’s also a .625" barrel and I’m not even sure if I could get a .750" barrels FSB small enough to fit under there. There’s only a very small amount of free space between the one I did on the .625" barrels gas block.
I’d suggest a 9" Lite Rail. That’s what I have on my 10" SBR.
Everywhere is out of the 9.0 Lite. Rob, would the DD Mk II RIS for the Mk18 Work? Found one of those.
Should be fine, that’s what the Mk18 RIS II was designed for (a 10" upper), the MK18 RIS II are 9.5" rails, that’s the rail that’s on my 12.5" SBR.
G&R built up some nice ones.
https://www.m4carbine.net/showthread.php?t=8207&highlight=Mk18
Here’s some other pics of some that I’ve ‘shaved’.
This LMT has a 12" Troy over it with an ARES piston conversion.
This Bushy barrel has a 12" Troy rail mounted over it.
My now 12.5" Bushy barrel under a Mk18 RIS II rail.
I guess the only viable option would be to shave the fsb. What do you use to cut and grind, a dremel? On a side note- if you can’t get a shaved fsb under a Daniel Defense Omega rail, what rail would you recommend? I really want one that has quick detach swivel cups with rotation limiters. I currently have a 7" DD Omega rail and I like the swivel cups.
I use a plasma cutter, die grinder and a grinder, then sandblast and refinish with Norrels along with the barrel.
I recommend the DD Lite Rail or RIS II rails or a LaRue. The newer LaRue rails have them built in. You can bolt on a DD QD sling mount onto any rail.
Dude, looks great.
Rob, what would be the turnaround if I order and get the RIS this week?
Thanks.
Just a big recommendation for Rob’s work. He shaved down the FSB on my LMT 10.5" SBR and installed a 9" LaRue rail. Looks and works great.
I’ve shaved several gas blocks as well and agree that this is the best route when looking for a lo-pro gas block. I used a hack saw to make the big cuts, and a dremel and hand file to round it off. I just paint them with hi-temp grill paint when I’m done.
In the white
Inside a DD M4 rail
Finished gun
I’ve seen your handy work, in previous posts regarding your low pro gas blocks, but never commented before. I must admit the finished product looks very nice and, more importantly, the fit and function is top notch.
Awesome job, Rob.
Thanks for the ideas. I have the metal working skills (used to be an iron worker), I was just wondering if there were any other options. I have been looking at Troy MRF rails- mainly the 10" version. Does anyone have an opinion on that rail with a shaved fsb? The main reason for the Troy is the fact that I don’t want to mess with disassembling the barrel (I don’t have a barrel wrench or armorer’s block). My other favorite would be a DD Lite Rail.
This isn’t a slight towards you, at all, so please don’t take it that way… but whenever I hear people basing their components off of not having the tools to install them, I cringe.
If it was a KAC URX rail, requiring the $400+ tools (or however much the two tools cost now) that would be one thing. But you’re talking about a barrel wrench and block… and possibly a strap wrench and torque wrench if you don’t have those / can’t borrow or rent them.
You obviously have the skills, from what you said above, and the competence to do the work. With the small cost of needed tools, compared to the expense of the rails you’re looking at, I’d go with whatever you really want… and pick up any needed tools.
Plus, you’re a guy… you can’t have too many tools. 
A week or less. 
I did exactly the same thing.
A word of note, the Larue rails are a really tight fight. It took cycles of grind, fit, grind, fit, grind, ad naseum.
If you want to keep the FSB available for a configuration change you can use a low pro gas block and pin it. Only thing is you will have a pin groove exposed when you put the FSB back on. YHM makes a nice low pro block for $20 and its a lot less work to drill a pin then hack a FSB all up.
I use this jig (http://www.rainierarms.com/?page=shop/detail&product_id=1089,my design) to dimple the barrel to align the block. Then its a matter of setting it up ind a mill or drill press. I drill in the center of the block with the bit 50% in the barrel and 50% in the block. Drill with a #31 bit, I use a cobalt jobber bit and ream with a 2/0 taper reamer to fit the pin. For the gasblocks a 3/4" long 2/0 will work and can be trimmed (length) up to fit as needed.
Well,
I dropped off my 10.3" Colt upper to Robb on Wednesday, he had the FSB “shaved” on Thursday and the the rail mounted on Friday.
I went with the 9.5" DD Mk II Ris from Rainier. I added a set of Troy FDE Flip-ups, from LaRue. They turned out to be 15.00 cheaper than any were else. All vendors were excellent and extremely timely.
For anyone that has never met, spoken, or had Robb do some work for you, he is excellent people. I highly recommend him for anything that you need done, and I highly recommend Virginia Arms for your needs in NoVA.
I am in the process of moving, so I will post picks once I get settled, but thanks Robb. Appreciate it.
Thanks for the nice words. It truly does look friggin’ bad ass!