New Sharps Relia-Bolt design using S7 tool steel.

[sinlessorrow]

Although I ALMOST completely agree with everything that you said ^^^, I will say - that I believe that in this day and age 20-30 years in business doesn't mean as much as it used to. A wealth of data and experts are available for companies to use and the results can be impressive. Designs can be improved upon, and a few kinks are to be expected when starting up. I hate Glocks, but I don't doubt that they're good tools that serve their purpose - no one trusted Glock either when they first came out. Now polymer handguns are everywhere. Is your broad range of knowledge so impressive that you truly know the effects of AR operation on a properly heat-treated S7 bolt? Metallurgy is one of my hobbies and there's no doubt that it can be made better than 158 in every way, regardless of the lug size argument, because lugs are big enough to do what they're intended to for the most part, even with weak 8620 bolts. Anything inferred about S7's incapability to function reliably as an AR bolt material has been garnered from inconclusive or incorrect data. The materials in S7 make it hands down a better alloy in every respect to 158 - now heat treating - that makes all the difference in the world. If too hard, it will be brittle and can crack - if too soft, it can deform as it returns into battery. Getting the exact heat-treat can be achieved through the hiring of experts and independent research. There, that is all.

It is worth noting none of the 11 entrants for the BCG PiP showed an improvement either. Kac makes the only imptoved bolt I can think of, but it takes a new barrel extension.

[Shao]

Here are some graphs and some machinists talking about it, I don't feel like going into a metallurgy lecture:

http://cartech.ides.com/ImageDisplay...ield+Strengths

http://cartech.ides.com/ImageDisplay...trength+-+Core

http://www.matweb.com/search/datashe...d42af5a6027d96

http://www.practicalmachinist.com/vb...7-steel-89412/

Basically: Higher toughness at higher hardness = better steel. They make jackhammer bits out of them.

"S7 is a shock resisting tool steel with excellent toughness and high strength, along with low to medium wear resistance. It has been widely used for many years to make chisels and punches which undergo shock loading, and has found increasing use for small plastic molds. S7 is easy to machine in the annealed condition and can be readily heat treated. It is deep hardening and in many cases (except for large sections) it can be air quenched, exhibiting minimal distortion on hardening. Due to its relatively high attainable hardness (HRC 58/60) it offers high compressive strength (resistance to deformation) while retaining good toughness."

Plus 158 was an alloy invented 50 odd years ago. Think of where material technology has gone since then...

[sinlessorrow]

Here are some graphs and some machinists talking about it, I don't feel like going into a metallurgy lecture:

http://cartech.ides.com/ImageDisplay...ield+Strengths

http://cartech.ides.com/ImageDisplay...trength+-+Core

http://www.matweb.com/search/datashe...d42af5a6027d96

http://www.practicalmachinist.com/vb...7-steel-89412/

Basically: Higher strength at higher hardness = better steel. They make jackhammer bits out of them.

"S7 is a shock resisting tool steel with excellent toughness and high strength, along with low to medium wear resistance. It has been widely used for many years to make chisels and punches which undergo shock loading, and has found increasing use for small plastic molds. S7 is easy to machine in the annealed condition and can be readily heat treated. It is deep hardening and in many cases (except for large sections) it can be air quenched, exhibiting minimal distortion on hardening. Due to its relatively high attainable hardness (HRC 58/60) it offers high compressive strength (resistance to deformation) while retaining good toughness."

Plus 158 was an alloy invented 50 odd years ago. Think of where material technology has gone since then...

And with a few changes to the shape of the bolt you can make one out of 158 that never breaks, ala the E3 bolt.

[Shao]

Just received word back from Sharps:

At Sharps Rifle Company, we have tested the Relia-Bolt extensively not only in a control environment but also in the field. We have thoroughly conducted investigation on the broken bolts and determined that those bolts have received improper heat treatment and resulted in premature breakage.

We have taken the proper measures to quarantine these affected bolts and are undergoing a voluntary recall on the sub-par improper heat treat bolts that our customers have received. Within the next weeks, we will be sending the proper heat treat Relia-Bolts to our customers.

Per our records, you have received the improper heat treat bolt. We will be sending out 2 replacement bolts to you next week.

Sorry for any inconvenience this may cause and thank you for your understanding.

Sincerely, SRC Customer Service Dept.




Sounds good to me!

[StainlessSlide]

Basically: Higher toughness at higher hardness = better steel. They make jackhammer bits out of them...


Plus 158 was an alloy invented 50 odd years ago. Think of where material technology has gone since then...

Unfortunately the situation is more complicated than "Higher toughness at higher hardness = better steel". A shape like an AR bolt which has sudden and extreme changes in cross section (say, between the lugs and the body) develops internal stresses on hardening, even with a low distortion steel like S7. The Charpy and Izod v-notch toughness values are the ones commonly given in tool steel brochures, but the specimens used for these tests do not have extreme cross sectional changes. Jackhammer bits also have smooth changes in cross section.

The sudden thickness change may explain the common cracking of the notch in the lower rear part of the bolt carrier.

These hardening stresses can lower the toughness of any steel. It may be that no through hardened steel is tough enough to give an improved lifetime in this application, which would explain the Mil-Spec of case-hardened Carpenter 158 (158 is a proprietary version of P-6 mold steel). Case hardening leads to compression stresses in the surfaces of parts, which inhibits the formation of cracks.

Maybe Sharps is using a heat treatment called martempering, which minimizes hardening stresses in intricate parts. I've never seen any data on martempered S7.

I like S-7 and I like the idea of an improved bolt, but real world experience will have to resolve this issue. By the way, S-7 has been around for at least 46 years.

[Malig8r]

Just received word back from Sharps:

At Sharps Rifle Company, we have tested the Relia-Bolt extensively not only in a control environment but also in the field. We have thoroughly conducted investigation on the broken bolts and determined that those bolts have received improper heat treatment and resulted in premature breakage.

We have taken the proper measures to quarantine these affected bolts and are undergoing a voluntary recall on the sub-par improper heat treat bolts that our customers have received. Within the next weeks, we will be sending the proper heat treat Relia-Bolts to our customers.

Per our records, you have received the improper heat treat bolt. We will be sending out 2 replacement bolts to you next week.

Sorry for any inconvenience this may cause and thank you for your understanding.

Sincerely, SRC Customer Service Dept.




Sounds good to me!

I received the same response. I have to say that I am impressed albeit a bit shocked to receive an email response so quickly and on a Sunday no less!!!

[LRRPF52]

Although I ALMOST completely agree with everything that you said ^^^, I will say - that I believe that in this day and age 20-30 years in business doesn't mean as much as it used to. A wealth of data and experts are available for companies to use and the results can be impressive. Designs can be improved upon, and a few kinks are to be expected when starting up. I hate Glocks, but I don't doubt that they're good tools that serve their purpose - no one trusted Glock either when they first came out. Now polymer handguns are everywhere. Is your broad range of knowledge so impressive that you truly know the effects of AR operation on a properly heat-treated S7 bolt? Metallurgy is one of my hobbies and there's no doubt that it can be made better than 158 in every way, regardless of the lug size argument, because lugs are big enough to do what they're intended to for the most part, even with weak 8620 bolts. Anything inferred about S7's incapability to function reliably as an AR bolt material has been garnered from inconclusive or incorrect data. The materials in S7 make it hands down a better alloy in every respect to 158 - now heat treating - that makes all the difference in the world. If too hard, it will be brittle and can crack - if too soft, it can deform as it returns into battery. Getting the exact heat-treat can be achieved through the hiring of experts and independent research. There, that is all.

There is no statement that S7 is incapable of functioning reliably, although its choice in this application is still subject to question, especially looking at its capacity to withstand extreme impact and pressure at lower temperatures where I spend a lot of time running high volume. I'm talking about -30C, over multiple day high volume courses of fire with M4's.

The main point I was trying to make is that building and maintaining relationships with suppliers, kilns, and establishing the testing protocols to provide a consistent product does not happen overnight, even with the greatest engineering and QC staff on hand. It takes a new company several years to work out a lot of these kinks.

From what it looks like here, S7 requires fairly tight QC and destructive testing in batches to really get an idea if the heat treating was done correctly. I have worked for companies where we submitted and paid for independent lab analysis for stress containment of some of our stress-bearing safety products, which is a snapshot in time on how many test samples you send them. To consistently make a stressed part for the market, you need constant testing and analysis of the component(s), as anyone dealing with this is aware.

Even if nothing changes in the raw material selection, dimensions, processes, finish treatments, and inspection protocols, I still want to see certs, and would continue to run testing on batches. In the case of AR15 bolts, I want to know what is going on with the alloy, surface hardness, ductility, etc., after it passes min/max dimensional tolerances on a check station with precision instrumentation.

It often takes successful companies years to get this down, even for the ones that do their homework and have solid engineering staff on hand. At any point along the production process, something can go awry, and slip past if these measures aren't religiously followed. Right now, we're seeing evidence that teething is still underway-totally normal for a new product.

I'm a huge proponent of innovation, but I don't trust much anymore. I have learned to be extremely skeptical, and will then verify over a period of years, not a range session or two, or even a season.

[Plasman]

Hrm, I ordered a reliabolt in June too, but haven't received an email.

[Regalkismet]

I received the same response. I have to say that I am impressed albeit a bit shocked to receive an email response so quickly and on a Sunday no less!!!

I received the exact same message today after emailing them... I too bought 2 bolts that I haven't even used yet... Just changed the extractor and ejector Springs.... One is a spare and one was going in a Wilson Combat Recon but I hadn't got it out to shoot with having just finished a couple other builds..... I have an LMT enhanced bolt in a rifle I just built and it seems like a pretty good solid design that I'm pretty confident would outperform your basic bolts like BCM on an average basis... But for the price it definitely should.

[hotrodder636]

Hrm, I ordered a reliabolt in June too, but haven't received an email.

Have you tried to contact them? I went to them, not the other way around.