Sharps Balanced Bolt Carrier BBC Group with Relia-Bolt Review
After developing what is arguably one of the most technologically advanced updated AR15 bolt designs, Sharps decided to design a carrier to complement the bolt. In typical Sharps design style, they didn't just duplicate a standard AR15/M4 carrier design, but started from the ground up and designed a new carrier design.
ABOUT SHARPS RIFLE COMPANYSharps Rifles are a household name in the gun industry with manufacturing that dates back to 1840 and accuracy that delivered some of the first truly accurate 1000-yard firearms. Most people know the Sharps rifle from the Tom Selleck starring Quigley Down Under movie which showcased the capabilities of the Sharps rifle in Quigley's hands. Today Sharps is part of the Broadsword sporting group which includes Sharps Rifle Company, A-Square, SRC Arms, H.H. Heiser, and Merwin Hulbert. The combined resources deliver a lot of capabilities and engineering ranging from production to custom. In this case, the company collaboration delivered a new way of thinking about a 100% compatible AR15 Bolt and carrier design.
FIT, FINISH, FEEL, FEATURES, & FUNCTIONS
Many things about the AR15 format have evolved and improved since its first introduction. Free float forends, adjustable gas blocks, coating and material technology improvements, new stock and buffer tube lengths, spring rate and buffer weight changes, triggers, sights, optics, new carrier designs and lightweight options... and the list goes on of things Mr Stoner never predicted. What has not changed since introduction is the bolt design and in most cases the carrier. There are a few people out there like Barnes Precision, JP, PWS, and YM who are making design and steel enhancements, however industry-wide, fundamentally the Bolt design has remained unchanged.
The NP3 coating (hardened Teflon) adds lubricity, self-cleaning, and longer part life and the upgrade to S7 steel improves tensile strength by 75% and yield strength by 60% over the industry standard premium Carpenter 158 steel. You need the added strength if you are going to fiddle around with the bolt lug profiles which took a bit of hands-on simulation to understand. The basics are that the bolt extends reliability window beyond what a normal bolt lifespan, environmental or weapon wear would typically allow.
Sharps identified that the carrier also had two primary performance degrading design issues; "the first being the rotational camming of the carrier during the unlocking portion of the operational cycle and the second being the canting of the bolt carrier group. The canting occurs upon firing due to the gas pressure exerted to the gas key which naturally causes the front of the bolt carrier group to rise and the rear of the bolt carrier group to be pressed downward during its rearward travel." Sharps was attempting deliver a new carrier design which does not torque or tilt and cycles as close to a balanced state as possible. Sharps used both computer design and profession design validation and testing of the final balanced carrier concept. The result of all the design, feedback and tweaking was the new SRC Balanced Bolt Carrier (BBC). The Sharps BBC is precisely machined from S7 steel which then heat treated and then NP3 coated. The NP3 coating reduces lubricant needs and makes cleanup simple and easy. The Sharps Balanced bolt Carrier will work on any .223 cased caliber such as .223/5.56mm, 25-45 Sharps and 300 Blackout calibers in any AR15/M4 format rifle and is a simple drop in upgrade.
WHY THE SHARPS RELIA-BOLT & BBC?
The standard $65 AR15 bolt available anywhere is essentially a non-optimal squares on squares engagement that requires near perfect alignment to work and I have seen carriers as low as $35 here and there. The value shopper can find complete BCG for well under $100, so why offer a $200 BCG?
The original Stoner design assures that in most cases the bolt will turn clockwise to unlock from the barrel extension lugs and the top of the cam will be held in unlocked position throughout the cycle by a groove in the upper receiver, the BCG cycles, picks up another round and relocks with a counter-clockwise twist after clearing the barrel extension lugs about the same time the top of the cam pin can move over in the can pin rotation recess in the upper receiver. Ultimately this is what is supposed to happen, however in extreme situations, grit, grime and wear to the cam pin, receiver, and piston rings can throw off one mechanical operation or another and cause reliability problems.Sharps obviously advocates proper gun maintenance and inspection to avoid and prevent the issues causing operational failure, however there are situations where high rate sustained fire, environmental issues, excessive receiver or cam pin wear/damage, and maintenance are not possible and that is where the Relia-Bolt will continue to operate.
Grit and grime can build up at the bolt and barrel extension union to the point where the bolt is not locking or engaging fully. With either extreme cleaning neglect or very hard use conditions the bolt may not be able to fully lock due to the crap stuck in the chamber or bolt/extension lugs. Sharps Relia-Bolt answer to this problem is deliver a self-lubricating and, for the most part, self-cleaning design. The bolt is coated with NP3 which for all practical purposes is hardened Teflon and is essentially self-cleaning which can literally be cleaned by wiping with a soft cloth. The tapered leading edges of the bolt lugs in theory also help to plow through buildup around the barrel extension lugs which could occur during extreme neglectful maintenance or situation where a high amount of debris may have found its way into the chamber area.
In a normal working state, the bolt is held in an unlocked position for the length of the cycle by the upper receiver capturing the cam pin so the bolt cannot accidentally lock mid-cycle or as it picks up another round. There is a notch in the upper receiver which is "timed" to allow the cam pin to rotate to a locked position after the bolt lugs have passed and entered the barrel extension lugs. However a severely worn upper or cam pin can create a situation where the bolt can partially start its counter-clockwise locking cycle just from the pressure of picking up a round or a sticky round in the magazine. When this happens the clocking/timing is off on the bolt and the lugs on the bolt and barrel extension collide versus interlocking, thus preventing lockup. The Sharps solution is to taper both the front leading edges and the left counter-clockwise facing edges of the lugs. This directional wedge effect drives through chamber buildup and will drive the bolt face back clockwise slightly back to an unlocked position to engage the barrel extensions without jamming.
Sharps decided to stay with a standard Carpenter 158 steel extractor simply because the benefits of the S7 steel are minimized to that of the standard Carpenter steel during extractor final heat treatment. Additionally there was a perception that a NP3 coated extracter would be too slick and actually decrease reliability. According to testing that was not the case, however the perception was there so inevitably Sharps decided on a standard premium extractor.From Sharps BBC Balanced Bolt Carrier perspective, I have never had an issue with even the least expensive carrier, however notable NP3 and Nickel Boron - NiBo carriers always run significantly smoother and are easier to clean. If you look inside a well worn upper receiver, you can usually see from wear inside the upper receiver that the carrier has not been moving in a balanced fashion. This wiggling around in motion is what Sharps was hoping to cure and in the end deliver smoother operating Bolt Carrier which should in theory move just straight back and foreward. I wish I could specifically say exactly how and where the weight was distributed, however the BBC balances right at the firing pin retaining pin hole.
REALITY VERSUS THEORY & FINAL THOUGHTS
The Sharps Relia-Bolt is an extreme performance/environment upgrade. In ten of thousands of rounds in over thirty tested AR15s, I have never had a chamber area get so dirty or cam/receiver wear so severe to create the jam situation resolved by the Relia-Bolt’s angled lug face. That noted, I do believe the lubricity, durability, and cleaning of finishes such as Nickel Boron and this NP3 (hardened Teflon) treated have improved functioning on rifles I have tested. Bolts with these coatings have been shown to run longer, smoother, cleaner, more reliability, and some claim lubrication-free. The NP3 coating is what I believe is the most attractive feature, however bolt breakage does occur and the stronger overall bolt design through the use of S7 steel could prevent bolt breakage. Bolt breakage is far more likely a failure than an out of timing bolt jam.
I did simulate the jam the patented Relia-Bolt design could prevent. To do this, I pulled the cam pin out of a carrier and simulated the overclocking issue and the Relia-Bolt clocked back into position where the standard bolt jammed. In short, things would have to be going horribly wrong with a severe amount of wear on the receiver cam pin channel and/or the cam pin itself for the lug tapers Sharps Relia-Bolt to be used. I can see where extreme environment, a long-term fielded AR15/M4, and/or extremely neglected ARs could develop enough slop so I term the Relia-Bolt as a “extreme performance/environment upgrade”.
It may sound like I am saying the Relia-Bolt is a solution looking for a problem, however I look at it a bit differently. Its an upgrade that can only improve reliability with the NP3 coating and decrease maintenance and in a worst case situation still deliver functionality. Another observation is that I am not one of those super hard core guys who wallows in the mud and muck to prove how far I can destructively push an AR15. Sharps design theory is sound and should do exactly what it is supposed to, because they have in fact had guys to these destructive tests.
Upgrading your AR15 bolt to the Sharps Relia-Bolt delivers another layer of reliability just as we all now swear by chrome, nitriding, nickel boron, and NP3 to deliver longer running, smoother, cleaner, more reliable, corrosion resistance, and lower lubrication requirements bolts over standard Mil-Spec phosphated bolts and the S7 steel is stronger as well.
The Sharps Balanced Carrier on the other hand is a difference you can feel once you start shooting delivering a little smoother cycling and less jolting cycling experience. The result is less muzzle rise and a flatter shooting AR15 in both rifles and AR15 pistol formats I have used these bolts in. The Sharps BCC are also full MilSpec M16 Carrier weight, so it will not impact functioning with most AR15s.
Beyond the Sharps complete Balanced Bolt Carrier Group purported performance advantage, the bolt carrier group is one of the most trick looking BCG's on the market. For the Mercury One Foundation AR15, my AR15 pistol, ultimate AR15 DMR, and Change Everything builds the Sharps Balanced Carrier Group was a standout component from a looks perspective in addition to its performance advantages. A while back in the first article, I questioned the price tag and said the Sharps Relia-Bolt and Carrier was a bit pricey, however the once $120 MSRP Relia-Bolt Sharps is now down to $79.99 and the complete BBC is now down to a $199 price which is pretty good considering this is inline with most other premium complete $200+ BCGs from PWS, Barnes Precision, JP, and YM. At $199 pricing, the Sharps BCC begins to look like a great deal considering all the features Sharps has packed in.
SPECS
S7 tool steel - when compared to mil spec Carpenter 158, the S7 steel provides a 75% increase in tensile strength, and 60% improvement in yield strength.
- Compatible with all existing .223/5.56 variant parts groups and bolt carriers.
- Same weight as standard Milspec BCG
- NP3 electrodes nickels-based finish
- Lifetime Warranty - MSRP $250 Street Price $199
SOURCES
SHARPS RELIA-BOLT - http://srcarms.com/