Hi all, I am a long time lurker on this forum, first time poster.

I have a Bushmaster BCWA3F 16M4 (16” barrel M4A3) on which I’d like to do the mods listed below and have some questions about each mod.  

Planned Mods
1. Replace the stock forearm with a free floating quad rail system
2. EOTech HDS sight
3. Front and rear flip up sights to co-witness with the EOTech (use iron sights and EOTech concurrently) and BUIS (iron sights only if the EOTech fails).

Questions
1. For the FF quad rail, I am thinking one of the usual FF units such as (no particular order):
   a. Daniel Defense M4Rail 7.0
   b. YHM Carbine length Solid 4-rail forearm YHM-9479
   c. GG&G Tactical Modular
   d. KAS FF RAS short (or URX/URX II, although from what I can tell these are not readily available to the civilian market)
   e. Larue Tactical 7.0 Carbine FF
   f. Troy MRF-C
   g. Samson  MRFS-Carbine

I prefer the looks of the Troy, Samson, GG&G, or URX/URX II level, uninterrupted top rail (better than the gap and being able to see the Delta Ring) – are there others that fit this way?

I don’t care for the looks of the standard round front handguard cap you usually see pictured with Troy/Samson.  I like a look w/o a handguard cap (like my RRA Varmint free float aluminum forearm) or maybe with the YHM-9484-A screw in end cap.  I think that gives a cleaner look.  What are my options in this area?

2. For the front flip sight, I believe I want to install a 2,3, or 4 rail gas block (e.g., YHM 9370, 9380, or 9390A) and add a detachable front flip sight (e.g., YHM 9584) instead of the alternatives such as a forearm-mounted front flip sight (e.g., YHM 9627) or a single-unit front flip sight gas block (e.g., YHM 9395 or 9394).  This approach gives me more flexibility to change out front flip sights if I want.  Is there any advantage to using a forearm-mounted front flip over a gas-block mounted front flip?

Quoted: Hi all, I am a long time lurker on this forum, first time poster.

Welcome.

I prefer the looks of the Troy, Samson, GG&G, or URX/URX II level, uninterrupted top rail (better than the gap and being able to see the Delta Ring) – are there others that fit this way?

Olympics Arms FIRSH

I don’t care for the looks of the standard round front handguard cap you usually see pictured with Troy/Samson.  I like a look w/o a handguard cap (like my RRA Varmint free float aluminum forearm) or maybe with the YHM-9484-A screw in end cap.  I think that gives a cleaner look.  What are my options in this area?

A. leave the round cap in place
B. Put a triangular cap on, though I can't imagine wanting to.
C. take the handguard cap off and leave it off.

I've never handled the YHM end cap but since the inside dimensions of handguards varies widely it would seem safe to assume that it will only work with a YHM tube.

2. For the front flip sight, I believe I want to install a 2,3, or 4 rail gas block (e.g., YHM 9370, 9380, or 9390A) and add a detachable front flip sight (e.g., YHM 9584) instead of the alternatives such as a forearm-mounted front flip sight (e.g., YHM 9627) or a single-unit front flip sight gas block (e.g., YHM 9395 or 9394).  This approach gives me more flexibility to change out front flip sights if I want.  Is there any advantage to using a forearm-mounted front flip over a gas-block mounted front flip?

There is no standard height for a gas block rail so your options for a front sight are limited to units that are compatible with the block you select.  Any other rails on the gas block are a waste especially if you've got a railed handguard.

As for handguard mounted sight vs. a gas block mounted sight, since top rails are usually the same height you are less likely to have a problem with mismatched dimensions.  But a sight attached to the barrel is theoretically more accurate since the front sight will always be positioned based on the barrel itself while a tube mounted front sight is positioned based on the tube.  The only way I can think of that it would make a difference would be if you had a tube mounted front sight then use a railed gas block and attached a sling or bipod to the gas block rail and applied enough pressure on the barrel to change the point of impact.

Ignore

Ignore

Rails - LaRue 7.0

Sigths - Troy

LaRue mount for the Eothing

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My first suggestion is NOT to get a fold down front sight until you've tried using the EOTech correctly (both eyes open, focused on target) with the fixed front sight in place.  

Secondly, I like the Daniel Defense rail myself.  I like it best because no other rail system offers ME PERSONALLY anything whatsoever I need that the DD doesn't have, and with extra ounces on top of it.  I like the oval shape, the light weight, the finish...  Funny too, because I always thought they were ugly as sin until I bought one and installed it.

After considering most every other forend available (PRI, LaRue, Troy and YHM) I ordered a DD 12.0 for my new rifle build.  It should be here tomorrow.  I really wanted a YHM or (gulp) Sampson because they were less expensive, but I just would not have been happy with it.

Thank you, Onslaught.  I didn't realize the correct way to use the EOTech was with the fixed front sight.  I'd like to learn more about that...are you aware of any threads discussing the topic?

Thank you, Onslaught. I didn't realize the correct way to use the EOTech was with the fixed front sight. I'd like to learn more about that...are you aware of any threads discussing the topic?

What I meant by the "correct way" is the part in parentheses...  

(both eyes open, focused on target)

Most any thread about EOTech has some mention of doing this...  It works the same for any red-dot sight.  With both eyes open, the front sight sorta disappears.  If it does get in your way, the LaRue mount raises the EOTech just enough to put the front sight WAY down at the bottom of the EOTech window, and gives you a QD feature on the EO.

If you look for threads about "fold down front sight, worth it or not" the concensus is always "not".  

Ah, I get it.  Thanks very much.  I'll read up and probably follow your advice.

Richard Harrison