Your Cart

AR-15 Low Mass Xtreme Performance Bolt (XPB) Carrier Group in DLC

AR-15 Low Mass Xtreme Performance Bolt (XPB) Carrier Group in DLC
AR-15 Low Mass Xtreme Performance Bolt (XPB) Carrier Group in DLC
  • Out Of Stock
Price in reward points: 240
categories: AR15 Parts, All products, Bolt Carrier Groups, Specials
MPI, HPT and Shot-Peened
Magnetic Particle Inspected, High Pressure Tested, and Shot Peened. Guaranteed to perform under pressure.
Limited Lifetime Warranty
Limited Lifetime Warranty


The Low Mass Sharps Xtreme Performance Bolt (XPB) Carrier Group Complete is comprised of our patented Relia-Bolt™  and our Special Low Mass Balanced Bolt Carrier. Low Mass Carrier is 1.7 ounces lighter than the Full Mass Carrier.  Made specifically for competition shooters.  The XPB undergoes a 24-hour thermal cycle proprietary heat treatment, and is finished with the DLC (Diamond Like Carbon) Coating. The XPB carrier displays the SRC logo machine cut and is visible when the ejection port door is open. The XPB fits standard AR-15/M16/M4 rifles chambered in .223/5.56, Sharps 25-45, and 300 Blackout calibers. Weight: 9.5 oz     

Technical Data

Bolt and carrier
S7 tool steel, shot peened and DLC coated (U.S. Patent No. 9,863,729)
Gas Key4130 Steel. attached with Grade 8 hardware, properly staked and DLC coated.
Cam pin
4340 Steel, Manganese Phosphate coated
Firing pin
Mil spec made of 8740 Steel, center-less ground, and Hard Chrome coated.
4340 Steel, Manganese Phosphate coated
S7, shot peened and Manganese Phosphate coated
Extractor pin
S7, shot peened and Manganese Phosphate coated
Mil-Spec Extractor and Ejector springs, Firing pin retaining pin, Gas Rings

  • Batch MPI and HPT tested
  • Tensile Strengths of 1550-1600 mpa, or 220,000-235,000 psi.
  • Toughness over 200ft/lb Charpy C-Notch
  • HRC of 46 yields a 15% increase in hardness at the same toughness comparing to Carpenter 158 & 9310.

Technical Data on DLC Coating

Coating thickness
2-4 Microns
Hardness HV 0.05
HRC 80+
Deposition method
Friction vs Steel
Dry 0.1

Limited Lifetime Warranty

If any SRC Balanced Bolt Carrier or Relia-Bolt™ is found to have manufacturer defects, SRC will repair or replace it at no charge.  Manufacturer defects include broken lugs, out of spec parts or defective parts.  Although our BCG is Mil-Spec, there are so many variables, sometimes a little troubleshooting, or fine tuning of parts may be required for proper functionality.  Before a part is replaced or refunded, SRC reserves the right to inspect and test part(s) in question to determine if it is defective.

Note:  Binary triggers will NOT work with the low mass carrier. 

Sharps will not guarantee proper function with the use of  steel cases, or foreign ammunition.

Color: Carrier and Bolt DLC (Diamond Like Carbon) Black

Order cancellations may incur a 15% restocking fee.  Please see return section

MPI, HPT and Shot-Peened
Magnetic Particle Inspected, High Pressure Tested, and Shot Peened. Guaranteed to perform under pressure.
Limited Lifetime Warranty
If any SRC Bolt Carrier or Relia-Bolt is found to have manufacturer defects, SRC will repair or replace it an no charge. 


Add review

Bad Good
Your email address will not be published. Required fields are marked *
Tags: BCG

Get the latest deals and more


This is one smooth operator. I purchased this BCG for my DPMS LR308 and it has made all the difference in the world. I have put over 200 rounds through it and not one failure even with extreme rapid fire. It makes the rifle cycle nearly twice as fast. Clean up is a breeze, just wipe off with a cloth and the built up carbon just wipes right off. I can't believe how easy it is to clean. The description doesn't say it but it has dual ejectors, I am sure this has something to do with why it works so good. It looks sharp looking too, oh no pun intended. I bought a second one to keep while they are on sale.

May 3, 2019
I completed my first ever build in May. Since the BCG is supposed to be the heart of the rifle I wanted to do my research to see which direction I should go. After seeing so many positive reviews on YouTube, I decided on the SRC in FDE. I've put about 1000 rounds through this rifle and I haven't one malfunction or hiccup. I'm very impressed with the craftsmanship and quality that went into this bolt. I have some more builds planned and I'll be using the SRC BCG's on all of them.

August 27, 2019
I have always been a quarter-bore fan but I had been out of the shooting scene for a few years. I changed jobs and a coworker introduced me to the 25-45 Sharps. After seeing the how close the ballistics were to the 250 Savage (one of my favorite cartridges) it was pretty much a no brainer that I had to build one. Collecting parts on a budget can really try one's patience, but I finally got it finished the way I wanted it using not only a 20" SRC barrel, but a Balanced Bolt Carrier with Reliabolt as well. The barrel shoots great and the bolt is tough as nails.

January 26, 2021
Wow this item is a work of art! I have owned a lot of bolt and carrier groups but this one far exceeds all of them on finish machining and applied diamond-like finish. perfection at the highest possible level! Great company. Excellent product

September 14, 2020
I do not think Their is a Better company out here to order a barrel from very responsive and helpful staff that ensure you as a customer fill number one from a 5 dollar part to a barrel your still made to feel that you are valued as a person. And the quality of their in house milled barrels is par none

September 5, 2017
Exactly what I was looking for in a bolt. I'm definitely going to pick up another as a spare and likely a full BCG at some point

April 9, 2021
As has been my experience with every order from SRC. This order for Pmags was handled very promptly and delivered as promised. Nothing but great service and products!

November 2, 2018
when you deal with the best,you get the best. thanks

December 16, 2018
Even during all of the craziness in the world with this covid mess Sharps delivered an outstanding product in just a few days. I have reliabolts in all my rifles and a few of your extreme performance carriers. I have and will continue to trust your products with my life. Thank You.

September 16, 2020
After shooting around 150 rounds no cleaning and getting sub 1" groups all day long without any hick-ups , very impressive. And getting wows and complements on the feel and look of the weapon I am happy to say that this is a winner. The timing and feel when shooting was top notch. Thanks guys for the excellent service and help when purchasing.

July 13, 2020
This BCG lives up to its reputation. Not one single misfire or extraction. Recoil seems a bit less as well, but could be me. Ran 120 rounds straight with a binary trigger. No issues. Cleanup was a breeze. Tiny bit of solvent on a rag and some wiping cleans it right up. Will definitely buy again for other ARs.

November 26, 2018
Great customer service. Seamless transaction. Was treated as if I was the most important customer they had. Great website, easy to navigate.

April 3, 2016