BYOU - Build Your Own Upper (SPR)

AT HOME AT RANGE.

Our Precision URGs are geared to the shooter that values quality over quantity. While our standard URGs are certainly accurate, these have a few more features and options like longer barrels and thermal fit receivers to make them real tack drivers.

For starters, every Precision URG uses a Thermal Fit upper receiver (marked with a "T" inside of a triangle on the left side of the receiver). What this means is that the receiver extension where the barrel is seated is slightly undersized, so the barrel and receiver will not fit together at room temperature. During assembly, the receiver is heated to ever so slightly expand the inside diameter of the barrel seat so that the barrel will fit perfectly. Once the receivers cools off, the fit between it and the barrel is extremely tight, enough that the barrel cannot be removed by hand. This removes any negative space between the two for a tight, bedded fit. This process leads to marginal improvements in shot consistency, but the peaks of accuracy are in those very margins.

There are several "flavors" of barrel on offer, too, to give you the ability to configure your build to suit your needs. From 20" heavy barrels for extreme rigidity at the cost of bullish weight down to shorter midweight barrels for a more flexible application envelope, you can improve your accuracy in the margins in a variety of roles. From Ballistic Advantage®, there is a wide range of lengths and profiles. All the BA® barrels are 416R Stainless Steel with .223 Wylde chambers, 1:8 twist rates, and are HPT (High-Pressure Tested) and MPI (Magnetic Particle Inspected). Some in bare bead-blasted finish and some with a black Nitride finish as noted in the dropdown menu. Much can be said about the .223 Wylde chambering, but the basics are that .223 Wylde is a hybrid chambering; somewhere between .223 Remington and 5.56 NATO. It has the same chamber angling as 5.56 NATO with a slightly tighter freebore. This means there is proper geometry for the safe expansion of higher pressure 5.56 NATO cartridges with a tighter "seat" of the rear of the projectile in the rifling. This gives you the flexibility to squeeze a little more accuracy out of precision .223 REM loads while being able to shoot the higher pressure 5.56 NATO loadings (M193, M855, etc.) without risking a catastrophic failure.

The Centurion Arms barrels are also cut from 416R Stainless Steel. They all have Centurion's unique "notched" gas block indexing system, which helps the gas block align perfectly. The MK12 barrels are made to Crane's specifications and optimized for use with MK262 ammunition (Black Hills 77gr equivalent). They have a heavier profile rear of the gas block drops to a longer .750 profile diameter forward of the gas block for use with OPS 12 suppressors. However, this profile is also compatible with Griffin Armament's PSR series of over-the-barrel muzzle devices. The RECCE barrels have the same MK262-optimized 5.56 NATO chamber with a heavier, tapered profile behind the gas block seat compared to the Mk12 profile. They have a narrower forward section to reduce weight by a bit, but are overall best described as a "mini Mk12" barrel. Both will be great shooters with heavier, higher-pressure loads and have been well respected by precision shooters for years.

Each upper receiver will come with a 5-shot proof group of match ammunition shot at 100 yards with your URG from a lead sled on a bench. Please note that there may be some marks on the top rail of the receiver from mounting the scope to shoot the group. The upper receiver, barrel, and bolt head are also all individually engraved with matching numbers noted on a certificate of authenticity that ships with your rifle for QC during the assembly process and down the line should you need work done on your rifle.

These URGs are highly configurable, so there are a lot of options to suit the discerning precision crowd to really dial things in to suit your specific needs. If anything is confusing or you have any questions, please let us know in through the Contact Us page.

COMPATIBILITY NOTES

* The Centurion Arms Mk12 barrels will incur marring forward of the gas block during assembly due to the tight fit and longer journal. For a clean finish, select a Cerakote® finish for the barrel.

** The Centurion Arms standard gas block is available without the tab for their proprietary notch interface, but this option is really meant specifically to be paired with their barrels.

Check out our Knowledge Base or click the links below for more information on the compatibility of certain parts. If you are unsure that a specific combination will work, please do not hesitate to reach out either through our webstore's contact form or directly through email at [email protected].

Model priced as shown $1256 MSRP: SPR Upper Receiver Group ($299), 18" BA® Premium Fluted SPR Barrel (+$250), Toad Brown™ Barrel Finish (+$50), Fixed Low-Profile Gas Block w/ Set Screw Installation (+$20), 13" CMT HDM™ Rail (+$139), Griffin Armament® PSR Flash Hider (+$109), Mil-Enhanced Bolt Carrier Group (+$219), Radian™ Raptor™ Charging Handle (+$95), Full Coverage Toad Brown™ Receiver Set Finish (+$50, +$25).

Due to their customizable nature, all BYOU upper receiver groups are built to order. As such, lead times will depend heavily on component availability and supplier processing times. Thank you for your patience!

REGULATION DISCLAIMER:

ALL NFA RULES APPLY for purchases of upper receiver groups. Any upper receiver with a barrel shorter than 16" must be used in a legal configuration. Check your local jurisdiction for specific requirements.