The low profile gas block with a forward mount front sight base on the barrel set up has crossed my mind. Was waiting on the barrel blank to check the dimensions.
IMHO, point loading a barrel with set screws creates compression that can transmit deflection into the bore. That is one reason for my stubborn refusal to accept the "pinned block".
The pinned blocks do not point load. Machined fit, slide into position, and the pin does nothing but keep it from rotating, or drifting forward or back. No pressure on the barrel. The pin groove is a half circle (ish) in the bottom of the barrel of whatever the pin is, 1/16", maybe smaller. There are a few that are complete holes. I can not remember what either of mine was from Centurion. Even with a complete hole, there is not really a weak point since the pin is reinforcing the drilled portion - plugging the hole via press fit. Ex - .0625x hole, .0625y pin. My Mk12, DMR barrel designed and expected to make shots to 700y, pinned gas block. Let go of your worries of potential accuracy problems - itty bitty bullet, low pressure compared to .308 calibers and larger.
View attachment 87682
I do not expect to fire 10,000 rounds a year out of either upper. Nobody is paying me to shoot "their ammo"!:{
Many AR competition shooters use the clamp on gas blocks, which spread radial compression over a larger area. Reducing the chance of point compression from set screws. (Which require a wall thickness reduction for the location dimples.)
I can neither confirm or deny, I don't know any comp shooters. Even the Mil. guys that contribute to the forums I frequent, don't touch on this much, other than if pinned, less chance of it being an issue in the field. I'll start up a thread and see where it goes.
I already have one set of BUS's that would work, using a RDS on the same plane. However, The RDS or magnified optics work better with my eyes. The BUS/ "rapid transition sighting system" is just for "eye candy". For a real life "close encounter" I would much prefer a laser designator. I just might focus on this route. Reality has a strange way of imposing itself on projects
Exactly - BUIS are borderline pointless with the modern RDS optics (I don't know that yours quite falls into that category - Modern to read 2008 and up ~ another hint to retire that girl and upgrade). Stupid long battery life, and take a heck of a beating and still hold zero. Especially for the privately owned shooters. For me it was a waste of $300 between my two rifles. I knew going into it that I can not shoot w/irons - current vision quality makes it only slightly better than point shooting.
Laser pointers are a double edged sword. ID's your proposed POI, as well as ID's where you are. In a civilized real life 2 way range with 1-2 BG coming at you, likely you only need stop one threat, and the other will turn tail.
That brings us to fore end length. Using the combat stance/advance and sweep, your fore end hand is farther forward than the traditional "off hand" hold. So what fore end length do you suggest for a 16" carbine.
What do you think of a vertical fore end grip. Crimson trace laser/light combo grip, for instance?
The current method of stance and support hand grip trickling down from the Mil. is to present the body armor/trauma plate 100% and a modified grip to accommodate a squared stance. For those that do not have body armor, the same theory applies. A shot to the torso squared on, has a higher probability of survival, as generally only one organ will take damage, whereas a shot at an angle may likely damage multiple organs. Ergo the need for proper shot placement.
The adopted forward grip on the handguard is an absolute PITA to maintain for any length of time unless you have weeks of solid practice to develop the muscles for it. It is designed as a fast present on target, recoil control (muzzle rise and follow through), sweep, and lower in to a "low ready" position that is mildly comfortable....Very long explanation that I won't get into. It works. I was a traditional bladed stance shooter when I got into this. If I have to hold on target standing for any length of time, I revert back to it, unless at a training class (I preferred not to be yelled at for my stance).
Foregrip is entirely up to the shooter. Some like the vertical, I liked my angled (Magpul AFG), some like just a little stub to act as a block/reference point while having the support hand wrapped around the handguard, and some go without any.
As for what length of handguard on a 16", if running a low profile gas block, as long as possible for me. I have long arms, and the longer the better for mounting a light (Streamlight TLRS) so it will not interfere with my grip shooting strong side or support side, and a longer BUIS sight radius (pointless for me).
My 16" middy has a Centurion 12" C4 rail, and I wish it was a 15". My Mk12 has a 15" (Midwest Industries SS Gen2 tube style) and I love it. I can get the proper locked elbow on my support arm and a good solid grip on the forward end of the handguard - no forward bolt on grip or light, just the bipod mounting stud.
Yes, I could cut out the top rail, similar to a RECCE. If that is the route taken.
The RECCE style does not have a notched handugard, it is a sight block mounted forward of the handugard/just behind the muzzle device as shown in the example I posted in an earlier post. An actual RECCE is using a rifle length gas port on a 14.5" - 16" barrel. Being a RECCE style, would be using a carbine or mid-length gas port (I don't know anyone who used the intermediate gas port ~ half way between carbine and middy) and the sight block gas port is not used for anything other than the sight. It just gives you your desire to have the FSP mounted to the barrel, and a longer handguard. Like I said, you are either going to be stuck with a 9" handguard, a 10" - 11" with the cut out for the FSP, or modify a longer one and hope you can get to the gas tube pin and clamping screws through the cutouts in the handguard. Your rifle, you gotta shoot it.
Yes, "Loctite", thread locker will certainly be used in clamp on/high temperature applications.
Have a "slip on" muzzle brake on a heavy target rifle that uses the clamp method and copious amounts of Blue "Loctite".
The Brake works fantastic. Just want to shoot it more to get the feel.
GregH
Talked to Tech support at Diamondhead.
Ordered the 13.5" VRS-T fore end.
It has a proprietary barrel nut and installation wrench.
Good description of their system;
http://www.ar15.com/forums/t_3_12/580422_Diamondhead_VRS_T_Angular_Handguard___Info_and_Pics.html
Just a piece at a time, here
Was this for the 16" or the 20" upper"
Got some cash from another factory buy-back of an unsatisfactory optic.
Tried a Minox scope. It was optically out of center. Obsolete model.
Got a full refund from Minox USA!
GregH
Aimpoint PRO can be found for $400 delivered. Might be some deals out there or on the equipment exchange (another subtle hint to retire your old one
As common with any optic, the good ones are expensive and the RDS are not exempt. $400 for the PRO, another $230 for a 3x Vortex magnifier (have not heard anything bad about the magnifier, only their RDS - seen it too) to $800 for an Aimpoint 3x magnifier. - You will want a flip up not fixed. 3x is too much magnification for contact to 20 yards. 2.5x for me is pushing it....referencing your 16" upper here. You will definitely be going with a good scope on your 20" I presume. There goes another $500 - $1500 - you know the game.
FWIW Burris Eliminator II and III have an integrated laser rangefinder that is getting really good AR user reviews ($650 and scary up), and Nikon has a scope that you can order custom BDC knobs for your own loads that is also getting really good AR user reviews ($200).
Even on your 16" there are several really good 1-4x variable scopes with illumination that would work well for you. Magnified vs. RDS - user preference. I have both, I can shoot both effectively strong side and support side with both eyes open and there is not much if any time loss in target acquisition and transition with my magnified.
Attention: TDR Forum Junkies 
, But I do know they are definitely not the cheapest parts dealer.
