The 458 SOCOM cartridge offers the practical ballistics of the legendary .45-70 in a modern AR platform rifle and is capable of firing 250 to 600 grain .458 caliber bullets in a lightweight, controllable package. For hunting medium to large game, bullets in the 250 grain– 400 grain weight range possess devastating killing power. We have found that the .458 SOCOM offers peak downrange performance when firing the purpose built Barnes 300 grain TAC TX bullet in the 1750fps – 1800fps velocity range.
The industry standard 1-14 twist barrels seem to be the best choice for over 350 grain bullets and/or subsonic loads and will shoot all suitable bullet weights acceptably well. We recommend this twist rate if you plan to use a suppressor to eliminate the chance of a baffle strike.
The SOCOM is also capable of launching 500- 600 grain bullets at subsonic velocities for suppressed or tactical use.
Building the .458 SOCOM takes only two caliber specific parts-a .458 specific bolt and barrel- Wilson Combat is further optimizing their .458 SOCOM rifles by adding an adjustable gas block, extra power action spring and straight gas tube as a standard reliability upgrade. Having the ability to easily adjust your gas volume allows the end user to fine tune their carbine's bolt velocity for a specific load’s power.
Minor machining has also been performed to the ejection port opening of the upper receiver to allow clearance for the larger cartridge.
The .458 SOCOM feeds flawlessly from many standard unmodified 5.56 AR magazines. Our extensive testing has found the Lancer L5 AWM magazine to be optimal for this round. The Lancer 20 round 5.56 magazine holds seven SOCOM rounds and the 30 round 5.56 magazine will hold nine. The .458 SOCOM achieves optimum ballistic performance in barrel lengths shorter than 16” so there is no need for longer, less portable barrels.
In our opinion the .458 SOCOM has several design and performance advantages over the.450 Bushmaster and the .500 Beowulf including improved functional reliability and the use of a standard AR magazine.
|| .458 SOCOM|
| Feed Ramps
|| Purpose Built .458 SOCOM Specific Barrel Extension |
|| Matte Bead-Blasted Stainless|
| Gas Block Seat
|| .875" Diameter by .900" Length - Dimpled for Set Screw|
| Gas System
|| Carbine Length|
|| 18" |
|| Stainless Steel, Type 416R, Barrel Grade|
| Muzzle Threads
|| Hunter - Fluted|
|| 1:22, RH, Six Groove, Precision Button Rifling|
|| 28 oz. |
Build Kit Includes:
- 18" Barrel
- Complete Bolt Carrier Assembly (NP3 Coated)
- Adjustable Gas Block
- Gas Tube, Straight
- Blue Print for Upper Receiver Modification
.458 SOCOM Ejection Port Modification Print
"1.55-1.60" inside rail height required to clear .875 SLR gas block
We are currently accepting backorders on out-of-stock .458 SOCOM items and will only charge your credit card account when the product actually ships.
The .458 SOCOM is an impressive caliber for hunting and defense but in order for the large, powerful cartridge to properly function in an AR certain steps must be followed.
1.) Our .458 barrels are chambered and set to minimum headspace using a PTG chamber reamer. This is the latest generation, improved SOCOM reamer and designed to accept properly sized brass only. Starline is the only manufacturer of .458 SOCOM brass and all brass should be completely full length resized prior to every loading. After firing, your empty cases may require trimming depending on your chamber dimensions and load. For all sized cases and factory and reloaded ammunition, we suggest using a case/ammunition gauge to check your ammunition’s overall dimensions.
2.) Since our build kits and rifles are set to minimum headspace to allow for slight headspace growth over time, you may have failures to completely chamber or close for several rounds after building your upper. As your chamber burnishes and bolt and locking lug surfaces mate together your SOCOM will start to feed as designed. This is a very powerful cartridge and we have engineered it to have very tight tolerances for long-term safety and reliability. Make sure you use plenty of light oil on all bolt surfaces when breaking in your upper. This will help the locking surfaces mate with your barrel extension. Do not use the black o-ring extractor insert unless you have failures to extract as they can impede feeding.
3.) Make sure you use the proper Extra Power Action spring shipped with your kit. When adjusting your gas block ensure that you have enough gas for proper function. Test your gas block by adjusting your flow to allow lock back on an empty magazine. If your gun locks back on an empty magazine after 3 single-loaded shots it is reliably locking back.
4.) We only use our modified Lancer magazines for best reliability in .458 SOCOM. Unmodified factory magazines will often have issues feeding blunt or round nose bullets. We do not recommend P-Mags or unmodified GI mags in .458 SOCOM.
5.) At this time we only recommend Wilson Combat or SBR brand .458 SOCOM loaded ammunition.
6) Gas block installation. Our barrels have one dimple for the rear gas block screw. When installing the gas block make sure the rear screw is tight in this dimple before tightening the front screw. You can drill an extra dimple for the front screw with the proper drill for extra security. Before permanently attaching your block with loctite or rocksett ensure that the barrel gas port and the gas block port line up. If your gas port is out of alignment with your block your rifle may short stroke.
7) Gas block adjustment. Follow the instructions with the adjustable block to tune your gas pressure. This is more easily accomplished with the handguard off the rifle. Remove the front adjustment lock screw and adjust your gas valve screw until your bolt locks back on empty with your lowest powered ammunition. Test your gas block by adjusting your flow to allow lock back on an empty magazine. If your gun locks back on an empty magazine after 3 single-loaded shots it is reliably locking back. When tuned to your satisfaction, lock the gas valve screw with the small locking screw.