A different type of metal for manufacturing bolts for bolt carrier groups?

[shadowspirit]

...Unfortunately, since bolts typically last more rounds than the average shooter will ever fire in the first place, mainstream success is basically out of the question, so the best they can hope for is to capture the niche market of high volume shooters, get them to sing its praises, then pressure the greater market to adopt it as the latest trend.

Sounds like something that can work. It would be something good for gucci AR manufacturers to advertise high volume shooters got such and such number of rounds through a BCG with the latest and greatest bolt in it.

[lysander]

Hence why TDP-thumping is stupid. Non of us need to justify out single unit purchases of an improved part to a bureaucracy by conducting exhaustive redundant laboratory testing to prove that it's better than the part that we replaced when we already know that it's made of materials which offer a tangible benefit over the original and therefore testing is largely unnecessary.
It's like, do we need to test to confirm that a tougher, more wear resistant metal would yield a tougher, more wear resistant bolt?

You can have fatigue issues, galling issues, corrosion issues, producibility issues . . .

That's why everybody tests design/material changes, at least smart people do.

You may not feel the need to justify spending $75 on a bolt that only lasts 100 rounds longer than a $50 bolt, and that's fine, it's your money. But "better" materials don't automatically mean "better" parts, as cost is always a factor when establishing what is "better."

While I am not a big fan of "TDP-thumping," what it does is allow you to get a defined quality level at the best economic level. (Whether or not you need military level stuff, or you needs can be met at a slightly lower lever, is another debate.)

[lysander]

Double post

[Echo40]

Don't get me wrong, the TDP is useful as a baseline point of reference for those who desire a battle-ready rifle, I'm specifically referring to those who treat it as gospel and will immediately trash anything that doesn't conform to TDP Specs, regardless of whether or not the specifications are superior to the TDP, or whether the TDP is contextually relevant to the user's intended purpose for their AR.

[Todd.K]

Book Reco: Ben Rich, "Skunk Works." Gives deep detail about just how much of a screaming nightmare Ti was to work with on the Blackbirds.

This was basically the dark ages of machining titanium.

I’m actually working on some Ti parts right now. Speed, feed, chip control, and good coolant are absolutely critical, but it’s not a nightmare with modern tooling and machines.

[lysander]

Took longer than I expected . . .

[Stickman]

I'm having bolts custom fabricated from tamahagane steel.

The Precious?

[MegademiC]

. . . (T)itanium surfaces in contact with each other or with other metals readily gall under conditions of sliding contact or fretting. Even with light loading and little relative movement, complete seizure of surfaces can occur. This situation is caused by adhesive wear in which microscopic asperities on the metal surfaces come into contact as a result of relative sliding and they tend to weld together forming a bond at the junction which can have a rupture strength greater than the strength of the underlying metal. Fracture then takes place at one of the asperities causing metal to be transferred from one surface to the other. The debris so formed gives rise to the accelerated wear that occurs with titanium."

https://www.azom.com/article.aspx?ArticleID=1219

The bolt and bolt carrier in an AR see not only high loads, but large relative movement. This makes them very poor candidates for titanium.



Anodized titanium has a surface as hard or harder than anodized aluminum, it can be as high as RHc 70 equivalent. Core hardness of a titanium bolt would be in the RHc 35-40 range which is similar to the core hardness of Carpenter 158 or 9310. It's not the hardness, but the galling.

And the strength is way less. Youd have to increase the size even if you solved the galling.

[lysander]

And the strength is way less. Youd have to increase the size even if you solved the galling.

The strength would depend on the alloy. Grade 5 would be just strong in tensile and compressive strength as 8620.

[MegademiC]

The strength would depend on the alloy. Grade 5 would be just strong in tensile and compressive strength as 8620.

Yeah, i was looking at grade 7.