"Varmint" Build

AR/M4 Custom Build Forum
1

About a year ago, I scraped my “varmint” shooting rig because of its weight. I had in my mind what I wanted to build, but couldn’t find the right parts to make it work. Partially because what I wanted wasn’t on the market yet.

Going off the success of my main training gun (https://www.m4carbine.net/showthread.php?t=33743&highlight=suppressed), I wanted to build a 16" AR that was dedicated for suppressed use, BUT could also have full functionality for when I take it to States where I don’t want to bring my suppressor. The question was, how to do it??? The Noveske SB was of course an option, but I wanted a longer rail so that was out. At a stopping point, I happened to be reading the GearScout blog and saw the SYRAC Gas Block. Some years ago, a friend and I built this exact same setup, but ours had a side wheel that adjusted the screw covering the gas hole. We ran into a problem in that we couldn’t find a way to keep the “wheel” from rotating (needed a detent lock on it). So when I spotted the SYRAC Defense GB, I knew that someone else had answered the question and built what I needed to complete my build!

Selection of parts.

Wanting a gun that would shoot under 1MOA at 100yds, I selected the BCM SS barrel. We then used our own G&R Tactical BCG and fitted a bolt to the barrel.

Having already installed the new Noveske NSR rail to my 10.5 gun, I knew that I wanted this rail system on my varmint gun. The NSR rail provides an anti-rotation system if used in conjunction with the Noveske/VLTOR MUR upper receiver so that was a no brainer.

At this years shot show, I was at the Lancer booth ordering mags when I noticed their lower. I was familiar with this lower from years past, but also knew that it was rude money (as it was billet). That’s when they informed me that this was their new one and was a forging (which was much cheaper). Hmmm, looks nice and I like the enlarged mag release and bolt release on the right side of the gun. So I selected one with the standard magwell adaptor and waited. And waited. And waited some more. Finally they came in and I built it using our LPK’s and the Geissele SD-C FCG.

For glass, I went with the Vortex Optics 1-4 HD. Quality optic with great glass that won’t break the bank.

After zeroing the gun, shot for group using BH’s 77gr MK’s. Unfortunately, it started to rain and had to hurry up my shooting. I did manage two shoot two 5rd groups at 100yds though. The first group was 1" and the second one was around .75. I quite honestly believe that if I was using a bit more powerful scope and it wasn’t raining that the gun could have produced .5" groups. Not bad for an autoloader using factory ammo!

Calibration of the SYRAC GB was pretty easy. I started out near the factory set position and then fired one round (empty mag) WITHOUT the suppressor on to see if the bolt would lock back. Then I would depress the detent through the rail (which the NSR is setup well for this as it has side slots that allow for easy access) and turn the screw one full revolution. Fired for affect until the bolt WOULDN’T lock back. Once set, I put the suppressor on the gun and fired one round to see if the bolt WOULD lock back.
On a 16" middy, the screw on the GB needed to be nearly flush with the end of the GB in order for the bolt to not lock back on the last round (without the suppressor on it).

Parts list:

Upper

Noveske/VLTUR MUR
BCM 16" SS barrel
Noveske 13" NSR Rail
G&R Tactical BCG
BCM GunFighter CH (MOD 4)
KAC 300M BUIS
Magpul MBUS 2 Front
SureFire FH 212A
SYRAC Defense Adjustable GB

Lower

Lancer (forged) lower
G&R Tactical LPK
Geissele SD-C
LMT Receiver Extension
LMT Castle Nut
G&R Tactical H buffer
Tactical Spring Co buffer spring (blue)
Magpul MOE Plus Grip
LMT SOPMOD
Novese QD Receiver plate

C4

2

So that Syrac gas block sounds like it allows the user to tailor to their setup and preferences? Sweet! Something else to buy in the future…

3

Yes.

C4

4

Grant,
Nice build. Can you provide additional info on the can cover?
Thanks.

5

Grant,

I’ve been very interested in the Syrac gas block ever since reading your thread on small port suppressed setups a long time back. Seems like it might be the answer to custom port sizing.

My only question would be whether it is durable and rugged enough to hold its setting for prolonged use on more of a “combat” rifle than a precision type rig? What are your thoughts on it?

Also, just wondering if you have any experience shooting the 75gr TAP T2 out of your rig? I have one with a 16" Noveske SS barrel and can’t get better than 2" groups with the TAP (using a Vortex PST 2.5-10), while everyone else seems to think its one of the most accurate factory rounds available. My next move it to try some BH 77gr…and possibly get a Geissele trigger…

ETA: Very nice build btw!

6

It is made by Elite Iron.

http://www.eliteiron.net/index.html

C4

7

Believe the same thing.

My only question would be whether it is durable and rugged enough to hold its setting for prolonged use on more of a “combat” rifle than a precision type rig? What are your thoughts on it?

Yes, I believe so. The reason why is because the detent locking system is very robust and is NOT coming out unless you put a tool in there to release the tension. Worst case is that you are shooting suppress, the screw backs out and you have a nornal AR. No problem there.

Also, just wondering if you have any experience shooting the 75gr TAP T2 out of your rig? I have one with a 16" Noveske SS barrel and can’t get better than 2" groups with the TAP (using a Vortex PST 2.5-10), while everyone else seems to think its one of the most accurate factory rounds available. My next move it to try some BH 77gr…and possibly get a Geissele trigger…

ETA: Very nice build btw!

No, but have shot that ammo before. Remember that 5.56 ammo isn’t going to be as accurate as the .223 version (typically). I have found this to be the case in Hornay and in BH’s ammo (where I have .223 77gr MK’s and MK262).

I would try some 55gr BH’s or TAP in .223 and also some 69gr, 75gr and 77gr to see what you get. Every gun is different so you will need to try different things.

To follow up on accuracy, yes the FCG does matter when shooting for group. I also put value in a fitted bolt and a flashhider/MB that is properly timed (meaning not installed with to much force). I time everything with shims so that it has the minimum amount of torque on the end of the barrel.

C4

8

Thanks for the replies Grant.

I guess I was wondering more if the set screw were to back out of the gas block (if the detent were to fail), would the gas block function like a standard block? Or would you have a gas leak where the set screw was? It is my understanding (unless the design has changed) that you can back the screw out all the way, that there’s no “stop” to prevent the set screw from coming out of the block…

And yeah, I guess I just expected more out of the T2 than what I got. It may have just been bad shooting on my part though since I was off a bench rest that might have been less than ideal.

I have just started reloading, so that will ultimately give me the most accuracy that I can get, but haven’t had time to do anything besides test out the T2. I’ll give the ones you mentioned a try (as components) once I get a chance to reload some…thanks again!

ETA: Just saw your FH/MB timing comment. Very interesting. Didn’t know that would matter. I had a local gunsmith (that I do trust) install the A2 cage and all he used was a crush washer. If you don’t mind, what do you look for when timing it? A certain torque spec?

9

Yes, function as a normal GB. So even if the screw got all the way out, the gun functions like a normal AR.

And yeah, I guess I just expected more out of the T2 than what I got. It may have just been bad shooting on my part though since I was off a bench rest that might have been less than ideal.

I have just started reloading, so that will ultimately give me the most accuracy that I can get, but haven’t had time to do anything besides test out the T2. I’ll give the ones you mentioned a try (as components) once I get a chance to reload some…thanks again!

Ya, reloading is going to show you the most accuracy for sure.

C4

10

Definitely a neat setup!

And after all the mental stamina that’s gone into gas port sizes :stuck_out_tongue:

11

Ha, no joke! Now we can all go on to argue about other things :stuck_out_tongue:

12

Thanks again Grant.

When you get a sec, please see my ETA in post #8. Typed it after your response…

13

In regards to timing a FH/MB, it has to be in a certain position while sitting on the barrel (hand tight). If it is too far off that mark, then I know that I will need to shim it to get it there.
I can’t give you a torque value, its just one of those things that I know it when I see it. A guess would be about 20ft lbs. So even using a crush washer, I would still time it so as to not use any more torque then around 20ft lbs.

C4

14

Thanks Grant. I think I have an idea of what you’re talking about here…if I had to guess, I would say that I’m more than likely over 20 ft/lbs, but I’ll check on it.

15

great build and looks awesome to boot!are you sure that your lancer lower isnt the billet model?ive heard of them going to new forged models,but you would think they would marked the model differently somewhat.i also have a lancer systems l15 lower less than a year old that i perceive to be billet that looks exactly like yours!i just went to their website and nothing is there regarding the forged models.i got mine from rainier arms,and agreed;these are very expensive,but very well worth the quality in my opinion.the only thing i feel they could`ve done to improve the lower, is provide a left handed(ambi)magazine release as well! :big_boss:

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Yes I am sure as it is hundreds less than it used to be. :wink:

We have 10 of these lowers in stock and they will sell for a retail price (with a standard block likw what is on mine) of $209.

C4

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thanks,that is awesome!my brother and a friend are looking to do a build each.i`ll let them know!:secret:

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We should have them up on the website soon AND we will be offering our LPK’s with them! :smiley:

C4

19

On the GB is it clock wise to make the GP smaller and Counter to open the GB up?

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When my funds build back up im gonna do a similar build by feburary. Cant decide what barrel (bcm ss or WC ss bull barrel). My question is why’d you op for a 16" barrel?