Looking for opinions about ar uppers

jonesy67

jonesy67

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I have only been in the AR game for about 5 years now with no mil or leo background. Everything I have learned has been from reading any article I can find about the AR15 and all the great people here at CGN. I don't think I will ever get tired of purchasing these rifles as the possibilities of modification are endless. So far I have a few free float barrels in the CC IUR/MRR's and one SA15.7 upper. Here is where I am asking some opinions.... I am looking to purchase a CQB upper and really like the LMT MK18MOD0-KIT1 but what I read about FSB's is that they are on the way out. I have heard that a barrel with the FSB gas block can shift POA/POI, but will it make enough of a difference for just a civi shooter from the bench? These FSB's have been in use for a long time now and I can't see if they were that bad that someone wouldn't have changed the design years ago.
I guess my question is.... in this day in age, with the products that are available do I free float or not free float?
 
Free-floating a barrel will make minimal difference if you're using it for CQB... Most shots will be offhand, so the advantage in accuracy will be minimized by your movement.

That said, I shy away from FSB as I hate them when using RDS. I have significant training scars from my use of the original C7 in the Forces and ARs at work, so I just can't ignore the irons if they're there. Why wouldn't you go with a low-profile gas block??
 
10.5" barrel is simply too short to be affected by POI shift by anything more than a hair thickness, not to mention it is a CQB setup, so it is not going to be a sub MOA rifle.

if you are just building a 10.5" upper but not an authentic MK18 Mod 0 like these guys ( https://www.canadiangunnutz.com/for...R-Mk18-Mod1-Clone-thread-Show-us-your-clones!) I would recommend looking at a DD Mk18 so you don't to swab out the FSB or handrail.
 
Phat Eagle - The "look" of a CQB upper with the RIS and FSB really defines a "military" looking rifle to me and I have been looking for a Colt Canada C8CQB since I started into shooting and can't find one. What is the disadvantage of having an FSB while using RDS? Would they not co-witness? Since I have 0 MIL/LEO experience, what sort of training scars can be built using this type of upper?

hbean - From what I understand LMT is the original MK18 upper supplier, would be as authentic as I can purchase. I have an NEA 10.5 (please no haters, I love my NEA) that has a low pro gas block and the DD RIS II forend/hand guard installed. If I swap out the stock it would look pretty close to a MK18 MOD1. I have only built one upper from parts and pieces and would rather purchase a complete upper with all the fixin's
 
jonesy67 said:
Phat Eagle - The "look" of a CQB upper with the RIS and FSB really defines a "military" looking rifle to me and I have been looking for a Colt Canada C8CQB since I started into shooting and can't find one. What is the disadvantage of having an FSB while using RDS? Would they not co-witness? Since I have 0 MIL/LEO experience, what sort of training scars can be built using this type of upper?

hbean - From what I understand LMT is the original MK18 upper supplier, would be as authentic as I can purchase. I have an NEA 10.5 (please no haters, I love my NEA) that has a low pro gas block and the DD RIS II forend/hand guard installed. If I swap out the stock it would look pretty close to a MK18 MOD1. I have only built one upper from parts and pieces and would rather purchase a complete upper with all the fixin's
Click to expand...

Realistically, there's nothing particularly wrong with having a red dot of some type either co-witness or lower 3rd co-witness with a front sight post. Some people just prefer to have no front sight obstructing their view. If you were to use a magnifier with the red dot, front sight posts can cause a slight ghosting effect in your field of view.

The MK18 Mod 0 / Mod 1 / CQBR we're put together by NSWC Crane, Indiana. LMT would have supplied the SOPMOD stocks used on certain variations, but did not build the upper receiver groups.
 
is the ghosting effect something some users can train past? I am on a flat range, max distance is 200 yrds. Is having a magnifier on a designated CQB rifle "common practice"?
 
Twan said:
Realistically, there's nothing particularly wrong with having a red dot of some type either co-witness or lower 3rd co-witness with a front sight post. Some people just prefer to have no front sight obstructing their view. If you were to use a magnifier with the red dot, front sight posts can cause a slight ghosting effect in your field of view.

The MK18 Mod 0 / Mod 1 / CQBR we're put together by NSWC Crane, Indiana. LMT would have supplied the SOPMOD stocks used on certain variations, but did not build the upper receiver groups.
Click to expand...

That's actually not entirely true they did have uppers for US military contracts on the Mk18, uppers only from what I can remember.
 
jonesy67 said:
is the ghosting effect something some users can train past? I am on a flat range, max distance is 200 yrds. Is having a magnifier on a designated CQB rifle "common practice"?
Click to expand...

The slight ghosting effect isn't particularly a big deal, and I have never found it overly noticeable. It depends what you define as "common practice". If you want to muck around with shooting up to 200 yards, either a red dot/magnifier combo, or a low powered optic will equally suit you.

Stoner99 said:
That's actually not entirely true they did have uppers for US military contracts on the Mk18, uppers only from what I can remember.
Click to expand...

if thats right, I stand corrected.
 
So yeah it boils down to what version of the MK18 you are building.
Mod 0 - with the FSB and KAC drop-in RIS (out of production but KAC RAS is close enough), buy the LMT and replace the handrail.
Mod 1 - with the low profile gas block and freeflow DD MK18 RIS, buy the DD M18 upper and you are pretty much done.
 
iloveak47 said:
Buy the lmt, you will love it.

Put the optic on a riser if you dont want to see the front post.
Click to expand...

iloveak47 - By putting the optic on a riser, if the optic takes a crap that would make the BUIS useless wouldn't it?
I haven't had an LMT yet so I am pretty excited with the prospect of grabbing one.

hbean - I am going to do some research but do you know off the top of your head the major differences between the RIS and RAS?

Question to all..... Who really likes the LMT SOPMOD stock? I can't do it, so I will never have a full clone. Is there another stock that would have been issued through the MK18 project? Sorry got away from the upper help for just a moment.
 
I think the differences between the two is the RIS has a larger inner diameter and the RAS has a spring loaded front tap to secure the handrail better, RIS has been out of production for a few years now and it is highly sought after by people building MK18 Mod 0 clones, so they are very hard to find and when you do find one they can be costly.

As with SOPMOD stock, B5 has a SOPMOD stock that is 95% correct to the original, for around $100.
 
If you are worried about not being able to use the buis then a qd riser may be for you.

And i LOVE my sopmod, heavier than needed but so nice to shoot with. If you want to build a clone the colt n1 or even the standard m4 stock is "issued", but most if jot all other stocks have been "seen in the wild"
 
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