This barrel will come with properly sized and spaced gas block journal dimples along the bottom for use specifically with Superlative Arms' Piston Retrofit Kits. The gas port will be sized approprieatly as well.
***Since piston conversion kits require set-screw detents machined into the barrel's gas block journal and require enough remaining wall thickness at those points, we've published a compatibility list for Piston Conversion Kits. Certain contours do not have enough wall thickness along the gas block journal when combined with certain bore/groove options. The minimum gas block journal diameter requirements are in the below chart (Please check this chart before ordering)
Rifle+2" length gas Superlative Arms Retrofit Piston Kits Not currently available.
Only .625" and .750" Gas Block Journal diameters are currently available. All barrels receiving Cerakote will have the entirety of the gas block journal masked off, so keep this in mind for either 1" or 1.92" long gas block lengh/journal options.
(The combination of Caliber to Barrel's GB Journal Outside Diameter)
Bore/Groove Minimum Allowable Gas Block Journal Diameter
.168/.172 .625"
.199/.204 .625"
.219/.224 .625"
.237/.243 .750"
.250/.257 .750"
.256/.264 .750"
.270/.277 .750"
.277/.284 .750"
.300/.308 .750"
.302/.310 .750"
.330/.338 .750"
.346/.355 .750"
.350/.358 .750"
.366/.375 .875" (NOT CURRENTLY AVAILABLE)
.408/.416 .875" (NOT CURRENTLY AVAILABLE)
.424/.431 .875" (NOT CURRENTLY AVAILABLE)
.442/.450 .875" (NOT CURRENTLY AVAILABLE)
.450/.458 .875" (NOT CURRENTLY AVAILABLE)
.492/.500 .936" (NOT CURRENTLY AVAILABLE)
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We use Mil - Spec parts for testing. If any Non Mil - Spec (Adjustable Gas Block, Heavy Buffer, Reinforced Springs, Light/Heavy BCGS, Piston Systems) parts are used, X-Caliber must be contacted. If not your firearm may not cycle properly.
For any calibers which use a big-bore extension (.350 Legend), a standard rifle upper (one without feed-ramp extensions) is strongly recommended.
FOR ENGRAVING OPTIONS FOR THIS BARREL, PLEASE CLICK HERE.
All AR Barrels that X-Caliber Manufacture receive the X-Caliber Logo engraving at the top of the barrel just behind the muzzle/threads. If you do not wish that your barrel receives this logo, please specify using the appropriate dropdown menu option when configuring your barrel.
Our ARs are tested with mil spec buffer tubes and springs. Any changes could change the way your AR functions.
Please check our Frequently Asked Questions for our current lead times.
Gas Block Selection
- max length with .625 Gas Block - 16"
- max length with .750 Gas Block - 24"
- max length with .875 Gas Block - 28"
- max length with .936 Gas Block - 28"
Gas Block Journal Length
All X-Caliber AR barrels are made to a 1.92" gas block journal length EXCEPT our Lightweight & Spaghetti contours which have a 1.00" length. Some shorter barrel and gas system length combinations with will also require a 1" gas block journal length instead of the usual 1.92" to make enough room for engraving our production stamp at the top front of the barrel.
Hand Lapped
Due to a logistical limitations and complications which arise with customer-supplied bolts (e.g. arriving too late, not properly documented, etc.), X-Caliber will now only guarantee 1 MOA or less on AR barrels with Rubber City Armory bolts that are purchased through X-Caliber.net and properly noted to be headspaced to the AR barrel on order (either via previous order # or through the same checkout cart as the barrel). Any RCA bolt ordered for an X-Cailber barrel in production, that is less than three weeks into production, will be headspaced to that barrel for no additional fee.
No Shipping outside the US
*Please refer to the footer of this page for up-to-date production lead-time estimates.
Fluting: Adds 1 week to order lead time
To Engrave This Barrel: Select all desired options and add this barrel to cart then click here.
For your crushwasher needs:
https://tromix.com/product/crush-washer/
or for only 1/2x28 crush washers:
https://www.tacticallink.com/Armageddon-Tactical-Stainless-Steel-Crush-Washer-For-12x28-Threaded-AR15-Barrels.html
https://www.joeboboutfitters.com/Crush-Washer-for-1-2X28-Barrels-p/jb-crushwasher.htm
For your gas tube needs:
www.whiteoakarmament.com
Need a Muzzle Thread Protector? Head here!
*NOTICE REGARDING 6MM CHAMBERINGS: Some SAAMI 6mm chamberings, such as 6mm ARC, 6mm Creedmoor and 6 PRC, might experience projectiles sticking in the freebore of the chamber's throat if the projectiles are at or exceed max-SAAMI projectile diameter specifications of .2435" (which is the same diameter as SAAMI freebore of the aforementioned chamberings). It has been noted in some instances that Hornady brand projectiles in 6mm can oftentimes be right at the maximum limit for what SAAMI specifications call for, and while safe to fire assuming the load adheres to SAAMI specifications, may experience projectile-sticking when extracting unfired rounds until the barrel has had 100+ rounds fired through it.
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X-Caliber Barrel Break-In
Procedure Guide
When breaking in your new X-Caliber Barrel, you should perform appropriate fire and clean cycles to normalize the bore surface. Each fire and clean cycle consists of a certain number of rounds fired (one to five) followed by a cleaning procedure (see below for reference), to be completed a certain number of times (1-25). These vary depending on the type of steel of the barrel, bore/groove diameter, velocity and pressure of any given round, etc. This is to be used as a guide. Since our barrels are hand-lapped, each barrel may break in a little differently. Some barrels may require more or less shots or cycles to break in than what is listed here.
416R Stainless Steel: Fire One Round then Clean: Do this 5-10 times. Fire Three Times then Clean: Do this 1 time. Fire Five Times then Clean: Do this 1 time.
4140 Chrome Moly: Fire Once Round then Clean: Do this 5-25 times. Fire Three Times then Clean: Do this 2 times. Fire Five Times then Clean: Do this 1 time.
Example: For a 416R Stainless Steel barrel, you would fire one round, then perform the cleaning steps outlined below a total of five to ten times (shoot 1 round & clean, done 5-10 times) before starting the three shot cycle where you would fire three rounds and then clean as outlined below, then proceed to fire five rounds then clean, completing the break-in procedure.
Each Firing Cycle (1 shot, 3 shot or 5 shot) should be followed by cleaning the bore (see steps below for reference):
1.) Using a one-piece, coated cleaning rod with a properly sized bore brush (wet with your favorite non-foaming bore solvent), carefully clean the bore from the chamber end toward the muzzle (3-5 passes is usually sufficient). If you cannot clean from the chamber end, be sure to use a bore-guide so as not to damage the crown or muzzle end of the rifling. Let sit 30-60 seconds before moving on to the next step.
2.) Push a dry patch down the bore. (2-3 times)
3.) Put a few of drops of oil on a patch and push that down the bore so as to leave a thin film of oil inside the bore.
4.) Begin a new cycle: Fire your next round or rounds in your next firing cycle and repeat cleaning as necessary.
It is recommended to keep a written tally of your current step within the process so if you get distracted you will know where you left off.
