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Discussion Starter · #1 · (Edited)
I'm just starting to map out my first AR-15 SBR build. Not ever having built an SBR before, I have a few questions and would also like opinions from those who have.

Use:
It will be used primarily for the range and 3 gun, maybe HD or SHTF if it ever comes to that. I plan to shoot it A LOT. Tens of thousands of rounds so durability is key.

Ammo: Will be using Lake City M193 and M855 surplus only. Rarely if ever will it see anything else. But if possible it would be nice to be versatile enough to use whatever ammo happens to be on hand.

Suppressed: It will be suppressed 95% of the time but needs to have the ability to be run reliably WITHOUT a suppressor in the event that the suppressor is damaged and has to be removed.

Range: It will be used MOSTLY inside of 100 yards but also needs to be capable of "minute of man" accuracy or better at 300.

Budget:
No expense spared. I'm not too concerned with how much it will cost when finished. If something costs a little more, I'll just save a little longer.

Reliability and Durability are MOST IMPORTANT. It needs to be able to handle a lot of use and abuse.

Everything else is up for debate. I've done a little looking so far and found LMT's 10.5" DI upper and 12" piston upper but wonder how well they will run suppressed with surplus ammo. Have also heard a few good things about Noveske's SBR uppers.

Is there a significant difference on how long you can shoot before cleaning with Direct Impingement Vs. Piston? Or any other significant differences worth looking into between the two, OTHER than cost? Gas blowback, cycling reliability, etc..

What size barrel? 10.5", 11.5", 12".. From what I've read, the shorter the barrel, the more finicky it becomes when cycling different types of ammo and locking the bolt back. I realize this has to do with the dwell time that the round is in the barrel after it has passed the gas block but does this hold true with an engineered solution like the LMT 10.5" DI or 12" Piston uppers? And how will this change when a suppressor is added into the mix?

Any suggestions or advice welcome. Preferably FIRST HAND experience. Thanks!
 

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I would go with a 11inch+ lmt. Sbr 556 rifles are hard on supressors. I dont know how reliable a ar15 supressed is but I can imagine a short barrel with a piston would be more reliable and not over gassed. I run a 8inch 300blk rifle but you are askinh about a 556. I will just throw this out there but if budget is not a issue why not sbr a scar16 that has a design around sbr supression. I have had 0 issues with mine
 

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I recently built a noveske Sbr in 5.56. It is a di, and those are supposed to be best for suppression, however I did not build for that purpose. In my research I found anything under 10 inch will have problems with erosion. For that reason I went with an 11.5 and I put a pig on the front. I originally built as a pistol for use with sig brace, but later went with Sbr. For a can set up I would not go shorter than a 10.5, and in my case it wasn't necessary as you can adjust overall length with a Sbr or sig brace. For internals I went with lwrc. For the lower parts kit and the bcg. The bcg is molded 1 piece and chrome Molled. If you need you can dura coat inside of upper where bcg moves to further decrease friction and heat. I later picked up a 10 inch 300 blackout upper by noveske and now run according to desires. If u can Sbr the lower or want to go brace route- that is best first step. I would add the pig is helpful if cycling issues with a di pistol Sbr kit under 10inch.
 

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No to rain on anybody's parade (I don't have one, 5.56 SBR not parade.....) but I do have a Noveske lower and I think the workmanship is excellent. I have heard great things about both LMT and Noveske and I do not think you can go wrong with either of them. I think it will boil down to price (which you have eliminated) and what options comes with the upper and your potential add ons. Let me say this, barrel barrel barrel. This is going to be the primary concern and the life of the barrel is probably paramount

That being said, I though that one of the problems with a SBR 5.56 is that even with the DI or Piston system, the gas feed from the barrel had to be bored out to assist with the stroking of the firearm.

There will also be erosion in the suppressor due to the unburnt powder doing its thing in the suppressor instead of the barrel. Choose your can carefully.

I have a pistol AR in 5.56 with a 8.25" upper and I do not think that I would ever put a can on it unless I was able to replace parts in the can. All my other AR's are either carbine or mid length.

I know that it is great to see all the latest hardware from the taxpayers that support the special ops people and others. And it is easy for them to say "hey, this just ain't working and we need to go in this direction" and not have to worry about costs or other factors like ATF approvals and tax stamps.

Good luck and keep us informed.
 

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LMT or Noveske, pick your poison, both are great.
Barrel length I would recommend 11.5" or 12". 10-10.5" barrels look cool and I have a couple but that little extra has helped my 11.5" setups run better with being less finicky.
These shorter barrel lengths are going to be harder on the suppressor and with the suppressor on it's going to make them dirtier, not much to do about it but to learn what lubricant can deal with it better and run as long as it can.

Some of my 5.56 SBR uppers.



On a build, pick a good barrel company, stick with someone good and that will help cut down on a lot of the headaches.
I've had good results with Daniel Defense barrels, gas port sizes seem to be right and chambers work good even dirty.
I also like to run a LMT enhanced bolt, not complete enhanced carrier group but just the bolt.
I do usually like to run a auto carrier from LMT but about any good company is fine.
With a suppressor and these short barrel setups I have found I prefer a PRI GasBuster charging handle but depending on your suppressor you might not need it.
I also play around with buffer weights till I find what I feel works best for the ammo I'm running and suppressed/unsuppressed, some I run a std and others are up to H2.

If your going to buy a complete upper and just plug and play, LMT, Noveske are a good start but look at Daniel Defense as well.
Accuracy, Range, Usage the 11.5 to 12.5 DI will do you.
My .02
 

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Get the 12.5" LMT piston, Noveske with switchblock, or Govnah adjustable gas block, combine with one of the new Specwar K or Saker K cans=winning.
 

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Hk touched a good point - Noveske will use a carbine length gas tube on their barrels - if you want accuracy and a tad more weight go with the SS barrel 1-7 twist

If you plan to run a suppressor - again look to Noveske as they have a switch block gas tube for a 10.5 up to 18" both SS and CHF chrome lined barrels 1-7 twist.... and you can also get a bolt matched to the barrel w/Noveske

To deal with the gas you have the option above - but where I want to add my 2 cents - look at LMT and their enhanced BCG .. there are several iterations out there and I believe the newest is the L7Q3B w/L7XA3 semi auto carrier - I run it on my 10.5 and no issues - other folks think the sweet spot for this BCG is 11.5 to 14.5 barrel (designed around a 14.5 w/carbine length gas tube) ... to me its what flavor you like. I think the problem folks run into w/builds on their uppers is if they get a used barrel (or bought what they thought was new)w/out of spec gas ports - out of spec go/no go bolt .... but again I have done a few builds and all but the last few were under a watchful eye of some serious builders.

Do you have to get enhanced no - but it addressed some issues that DI guns just have and LMT and CRANE NSW helped work out w/their BCG
If you don't go that route get a good BCG made out of carpenter steel - phosphate coated - proper staked gas key - good CRANE o-ring for the extractor and ensure it has been MP/HP tested...my final thoughts get a bolt matched to the barrel.. if you can call it my OCD but it has never let me down or guns that I serviced while I was active duty.

Its fun for me and I have learned a lot - my point being a fitted bolt to a barrel will do better than most 'other' builds yes - but that only one component of the build - torque values on the barrel nut - gas tube - gas block seal to barrel etc etc etc ... any one thing not just right or slapped together could mean the difference between a consistent 1moa build -vs- a buld that you will be disappointed in and just chase rounds all over the paper.

IMG_1236.JPG my vote - Noveske or LMT cant go wrong

Modified cam path increases dwell time, allowing for a much easier extraction.
•Five gas vent holes.
•Extractor claw engages more of the cartridge case rim to ensure positive extraction.
•Geometry of locking lugs decreases stress.
•Manufactured from a much stronger material than GI issue bolt.

Carrier: L7XA3 or L7Q3
The L7XA3 (semi only) or L7Q3 (full auto) includes both our enhanced carrier which incorporate a longer dwell time allowing barrel pressure to be greatly reduced and promoting easier extraction, and our enhanced bolt which has a more resilient "easy clean" coating and stronger heat treat, as well as the cartridge case being fully supported by the bolt face. Choose model below.

LMT BCG's include a HPT/MP tested bolt and Crane O-Ring.

The Bolt Carrier features a third port for venting gas, as well as a bolt with split lugs to reduce stress. The Bolt also uses a dual spring setup, and is chrome plated.
 

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I'd opt for the LMT over Noveske, but that's just me, both are top notch... And to be truthful, I'd go KAC over either if you want the very best.
 

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Discussion Starter · #11 · (Edited)
Thanks for all the replies. But now I have a few more questions. Talhoffer, you recommended going with an 11.5" -12.5" barrel to save wear on the suppressor and gain more reliability. Were you talking about building an upper from scratch? I really like LMT's Monolithic Rail Platform but after looking into it more Noveske's 12.5" CHF chrome lined Switchblock Barrel is looking better and better.. I already planned on going with the LMT full auto enhanced bolt and carrier so that's good to hear.
 

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Thanks for all the replies. But now I have a few more questions. Talhoffer, you recommended going with an 11.5" -12.5" barrel to save wear on the suppressor and gain more reliability. Were you talking about building an upper from scratch? I really like LMT's Monolithic Rail Platform but after looking into it more Noveske's 12.5" CHF chrome lined Switchblock Barrel is looking better and better.. I already planned on going with the LMT full auto enhanced bolt and carrier so that's good to hear.
Only downside to the switch block - if shoot it solely suppressed w/it off or on ...it can get frozen into place - do not lube it (it will just burn off) try to get it w/the boot wrench and every so often move position of the SB so it wont get stuck in position ;)
 

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you recommended going with an 11.5" -12.5" barrel to save wear on the suppressor and gain more reliability. Were you talking about building an upper from scratch? I really like LMT's Monolithic Rail Platform but after looking into it more Noveske's 12.5" CHF chrome lined Switchblock Barrel is looking better and better.. I already planned on going with the LMT full auto enhanced bolt and carrier so that's good to hear.
Build mostly but if you look around you can find some places that will build them for you. 12-12.5" uppers are not real popular but they've been available. Novekse first brought the 12.5" setup to my attention a number of years ago when I started looking at 5.56 SBR and suppressors.
I've not used one of the BMC 12.5" uppers but some of their other uppers I've used have been good, I mostly put together what I want vs buying complete uppers for myself.

AR-15, 12.5" Carbine Upper ReceiverGroup
 
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The LMT 12" MRP Piston upper is in stock at DSG Arms, it has a chrome lined barrel. The MRP system looks cool, and the barrels are much cheaper than the SCAR's!
 

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Well, first I would build a SCAR 16S SBR before a LMT or Noveske DI SBR. The SCAR handles suppressors pretty well and has a gas switch for them. Plus they look badass and you can just buy the 10" barrel.

Second, SBR and 3GUN?

Third, between Noveske and LMT I always prefer Noveske. Noveske also has something called a "Switch Block", you might look into that. LMT does make a good weapon, but I suggest DI not piston. I personally don't care for ANY AR with a piston grafted on, that's why I suggested the SCAR.

If you are going DI Daniel defense and BCM also make excellent ARs.
 

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Well, first I would build a SCAR 16S SBR before a LMT or Noveske DI SBR. The SCAR handles suppressors pretty well and has a gas switch for them. Plus they look badass and you can just buy the 10" barrel.

Second, SBR and 3GUN?

Third, between Noveske and LMT I always prefer Noveske. Noveske also has something called a "Switch Block", you might look into that. LMT does make a good weapon, but I suggest DI not piston. I personally don't care for ANY AR with a piston grafted on, that's why I suggested the SCAR.

If you are going DI Daniel defense and BCM also make excellent ARs.
Nah, registered AR lowers are way more flexible than SBR scar uppers. You can put just about any AR upper on it, doesn't have to be DI.
 

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Nah, registered AR lowers are way more flexible than SBR scar uppers. You can put just about any AR upper on it, doesn't have to be DI.
This is why I've done a couple AR SBR's first before starting my SCAR16 SBR. More calibers and barrel lengths with the AR and just the one or more lowers if you want.
 
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Discussion Starter · #20 ·
So for those who have ran a Noveske Switchblock barrel or know someone who does, what does it look like for rail options? Are there any rails you can use other than the one from Noveske that's made for the Switchblock or the Larue rail that stops just before it? I'm sure a lot people just mill or "Dremal" a hole in the top of the rail to operate the switch. Anybody have any pics?
 
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