NFA newbie- dedicated suppressed 11.5" build questions

General Firearms NFA
1

Hi guys, I’ve been doing a lot of research but couldn’t find the answers I was looking so I figured I’d give it a shot here:

I have a Huntertown Arms 5.56 Kestrel coming, maybe another 1-2 months on the stamp. Same timeframe for the SBR stamp. IN the meantime I am preparing my SBR build and I have a few questions:

Here’s what I got so far:

Registered BCM Lower built by Grant with Geissele SSA, suggested I go with H2 buffer and blue Springco Spring. Question 1: I’ve heard posts here recommending H3 buffers and green Springco springs? Thoughts?

The upper:
BCM 11.5" upper with DD RIS II handguards
Question 2 : For a dedicated upper, who can do work on the gas port or should I go with a Switchblock? Is stock alright?

Other parts of the rifle include Surefire X300, Aimpoint T-1 / LT660, Larue Handstop and MS3 sling.

I mostly shoot PMC Bronze due to price but will try to buy M193 variants whenever this price surge cools down.

Goal of the rifle: all purpose. Must be ready for home defense, range, classes, etc. I do have a backup 16" BCM/DD rifle but I want this to be as reliable as humanly possible.

Thanks in advance.

2

Green springco springs are for rifle length systems i.e. Vltor A5…it won’t work with your carbine setup. You will more than likely be good to go with the H2 and blue springco spring.

I don’t own a BCM 11.5" upper, but everything I have heard is that it will be good to go as is. I belive if you wanted to get a switch block you would have to dump the DD rail due to clearance and access issues for when you would want to switch settings. Just look at a noveske 10.5" upper with switchblock and you will see what I mean.

Overall it looks like you will have a solid rifle. I would put it through its paces once it is togther then go from there.

3

If you can get an upper with a reduced size gas block (for a pure dedicated host), you can run much lighter buffers. Even having gone that route, since I’m running a somewhat longer ACS stock anyway, I’m still running a VLTOR A5, and really happy with it.

4

If I were going dedicated, I’d get the port sized accordingly.

I’m not even sure how one goes about this. Almost everything out there is over gassed to some degree.

5

Kind of have to agree with markm.

Are you going to be using the lower on another upper? If so you might want to look at a few more options.

6

No, this lower will be mated just for the suppressed SBR. I have no problem putting a H2 and blue spring in there, but I have no clue how to get the gas port correctly sized. What do I have to do and is it worth it, especially if I shoot a variety of ammo?

7

Once the port is reamed, you can’t downsize it again.

I ran into this problem with my 11.5. It was way over-gassed WITHOUT a silencer installed. I had to use an insertable port that goes into the FSB to choke some of the gas down.

As far as shooting a variety of ammo… that’s the catch… I’d just get a BCM 11.5 and be done with it. Iraqgunz, here, has had good look with that combined with an A5 stock for thousands of rounds.

8

Your barrel already has a gas port which is not tuned for suppressor use…meaning you’ll be overgassed. Only way to change a gas port to a smaller dimension after being drilled is to plug and re-drill OR use an adjustable gas block.

Look into the SYRAC Adjustable Gas Block

Also, Wilson Combat just came out with one that is similar design and made as a “kit” with the gas tube. Not sure on the actual function of it and user interface, but I’m sure its good if it’s from Wilson.

I have the SYRAC for a dedicated suppressed 11.5" and can tell you that it is solid and works!

9

I thinkt hat may be what I go with. I shoot whatever is cheapest at the moment, and that has fluctuated wildly from IMI 5.56 a while back to PMC bronze now. I think I would have problems if I had a tightly tuned gun running all these different pressures.

10

Gunz has shot all that stuff in his barrel… and some of the Hornady steel cased too.

11

A 7" rail will fit behind the Noveske switchblock on a carbine system. But unless you buy a Noveske barrel, you’ll have to use the clamp on version.

I don’t care for either if those limitations.

You could always try an adjustable has block to reduce the amount of gas in your face, but I think you’ll be fine with the H2 and blue Springco.

12

Have you played “switch the buffer/spring/reciever extention till you find what works” game. So much fun…

Seriously, there is a lot of things you can do before you start on the GP. Lots of info on sbr’s on here too.

13

If the gas port is right, you don’t have to play any games. H2/carbine or A5 buffer system and done.

The wrong port is the root of many AR problems.

14

The “switch the buffer/spring” game is just a bandaid for the real problem. You want to cure the cause…which is at the gas port/gas block.

15

This is true. I just like to meddle till I figure out what’s wrong.

16

So really the only option is to get the SYRAC, switchblock, or buy my own barrel and drill it out myself?

17

No. I’m not even sure you can get a barrel that has an extension but no port. :confused:

18

Seems complicated then. Maybe I’ll just order a switchblock Noveske upper and be done with it, lol.

19

You said this is dedicated suppressed, right?

20

Yes, it is. What are the disadvantages to having the wrong gas port but compensated with the right buffer and spring?