SPR type rifle build

[ABN]

I'm looking to build an SPR type rifle 18" barrel, not an exact copy/replica, but a rifle similar in concept. The only one's I have seen during my stint had a tube w/ a flip up sight instead of a rail, with a fixed buttstock or a M4 buttstock. I must warn in advance, my technical expertise isn't good.

I'm looking at barrels and leaning towards the rifle length right now so...

1-If the weapon is going to be shot unsuppressed what is the best gas system to use, rifle or mid-length ?

2-Is the use of heavier buffers in short barrel rifle's specific to a carbine length gas system ? Not sure, but I thought it was possible if a barrel went from 20" to 18" it was better to run a heavier buffer. I was thinking a H buffer, although it might not make any difference. The stock I intend to use is a Magpul UBR, when I can find one. So...

3-Does going from a 20" to 18" require a different gas port size ? Or is that limited to modifications to shortened barrels on carbine gas systems ?

4-I want to have a pinned gas block. What brand/model gas block would be best ?

[Warrior]

i just did an 18" with a Noveske barrel. It was sort of a custom job as I specified rifle length and a 1/7.5 twist rate. His SPR barrel comes with an intermediate length gas system which IIRC is between rifle and mid in lenght. His barrels can also com with his gas block pinned. Noveske is not the budget buy for sure but it is definatly high end quality stuff. To me it shoots just as good as a custom barrel from a kreiger or lilja blank as I have had those in the past.

Rifle vs Midlength. pic one you like better both are fine. I personally like rifle lenght on a precision gun.

if you run a UBR you should be fine with the standard carbine buffer on a middy or rifle. Alot of factors play into this but I ussually run the heaviest buffer that will cycle my action reliably with my ammo.

The gas port size you won't really need to worry about. whatever barrel you go with will have it drilled already. oncce you start getting into SBR's then the GP size comes into play.

If going with a stripped barrel then you will have to get your gas block pinned by someone who can do the work like one of the excellent site sponsers. their are a multitide of GB on the market, do you want a GB front sight combo, under the handguards GB etc. more specifics and I will be able to offer you some better choices.

[ABN]

As far as the gas block, I wanted an under the handguard type. Correct me if I'm wrong, some use set screws with locktite. I want a pinned gas block. I was curious I am not that familar with the commercial AR market, just military guns.
The type of handguard, not final, but I did some research I was thinking the longest Larue rail somewhere between 13 & 14 inches, that covers the gas tube on a rifle length. Not sure how it would balance with a ubr stock though.

[David Thomas]

As mentioned in another recent thread, the Noveske VIS SPR gets my vote.

http://noveskerifleworks.com/cgi-bin/imcart/display.cgi?item_id=u18vis556&cat=57&page=1&search=&since=&status=


From Noveske's web site:
"The 18" SPR 5.56mm Upper

--Noveske 18 inch SPR SS barrel, with OPS INC 12th model collar shelf in the correct location, 1 in 7" twist
--Extended feed ramps
--VIS 12" monolithic upper
--Pinned 17-4 gas block
--Intermediate length gas tube
--Auto bolt carrier
--Shot peened and MP tested bolt
--Forged charging handle
--Vortex flash hider
--Optional BUIS (Troy Back Up Iron Sights)

Sights, optics, and accessories can be added. This is a complete upper, test fired, and ready to be installed on your complete lower.

Since the development of the 18" SPR barrel, there has not been a proper gas port placement to work with the desirable barrel length. Now there is a perfect combination, introducing the "Intermediate Length" gas system. Developed by Vltor Weapon Systems, and perfected by Noveske Rifleworks, the intermediate length gas system offers the ideal gas port placement, providing maximum accuracy and reliability. Overall, the intermediate length gas system (1.5" shorter then a rifle length) was developed from feedback from end users and industry professionals. Accuracy and reliability are the best characteristics of the intermediate length gas system."

[ABN]

Noveske, looks like a great option. It is expensive at $430, but it does have the gas block already pinned and a what looks like a bead blasted finish. When compared to a stripped $300 barrel, plus gas block and installation,plus finish, the Noveske is probably more expensive, but comparable.

A couple more questions...

1-5.56 match chamber ? Somewhere between 5.56 and Wylde I would assume.

2-So w/ the intermediate gas system, does anyone know if the gas block fit with no modification with a Larue 12.0 rail ?

[David Thomas]

.

2-So w/ the intermediate gas system, does anyone know if the gas block fit with no modification with a Larue 12.0 rail ?

Yes, the Noveske gas block will fit under a Larue 12.0.