HPT and MPI testing. Why?

[1168]

It's part of mil spec to keep parts suppliers honest, not required by a good company who tightly controls their raw materials. Knights Armament does not do HPT and IIRC has stated it cuts bolt life in half, they also warrant their bolts for +20,000 rounds.

I think Snow Colt skips HPT, too, don’t they?

[TMS951]

I wonder if car companies over heat the brakes on ever new car to make sure it can handle normal heat, or if aircraft companies subject the landing gear of every new airplane to an impact higher than it ever would in real life to make sure it can handle a hard landing?

I understand the wisdom, kind of. It just feels like there has to be a better way to it. Like just get material that’s really good and quality controlled? Don’t machine it too fast, ect.

Maybe make the cam pin hole smaller and round the locking lugs? I realize after I typed that, it’s done by a company already. Cross comparability is an issue. It’s too bad it wasn’t the original design.

[lysander]

I wonder if car companies over heat the brakes on ever new car to make sure it can handle normal heat, or if aircraft companies subject the landing gear of every new airplane to an impact higher than it ever would in real life to make sure it can handle a hard landing?

I understand the wisdom, kind of. It just feels like there has to be a better way to it. Like just get material that’s really good and quality controlled? Don’t machine it too fast, ect.

Maybe make the cam pin hole smaller and round the locking lugs? I realize after I typed that, it’s done by a company already. Cross comparability is an issue. It’s too bad it wasn’t the original design.

Yes, as a matter of fact, certain life-limited components are proof loaded and inspected to verify integrity.

Turbine blisks, one-piece compressor rotors, hydraulic cylinders, pressure vessels, landing gear struts

On the ground based side of things, cranes are proof loaded above the maximum certified weight on a regular basis.

If the service load was close to the maximum allowable load, you might have a point about the proof load being damaging. However, stuff like bolts have a substantial safety factor in the design, so the proof load keeps even the proof loading from being damaging.

EDIT:

Machining at the correct speed does not preclude internal material flaws.

And last: Making the cam pin hole smaller just moves the weak point from the bolt to the cam pin.

[the AR-15 Junkie]

When I was working on Minuteman Missiles in the Air Force decades ago the hoists that we used to raise the Nukes off the missiles were marked, Proof Load Test at Twice the Rated Capacity. That entire quote was painted on the hoists.

[MegademiC]

I dont care who makes it, raw material flaws can and do happen, and process control is a numbers game to minimize chances while remaining profitable.

[lysander]

I am still waiting for the answers to these two questions:

1) It has been claimed multiple times that Knight's guarantees their bolts for 20,000 rounds, where does Knight's state this?

2) Can anyone link to a technical report that states that proof testing measurably reduces part life?

[GTF425]

1) It has been claimed multiple times that Knight's guarantees their bolts for 20,000 rounds, where does Knight's state this?

On their website.

https://www.knightarmco.com/our-products

Under SR-16:

The heart of the product line is the E3 bolt, a proprietary design with a 20,000+ round lifespan.

[lysander]

On their website.

https://www.knightarmco.com/our-products

Under SR-16:

That is not a guarantee, that's advertising.

[GTF425]

That is not a guarantee, that's advertising.

Neat.

[lysander]

This is what they actually state in regards to their products:

Knight’s Armament Company & KAC / KMC Limited Warranty:
Products and firearms are warranted to be free from defects in material and workmanship. This warranty shall apply to the original owner for a period of 1 year from date of purchase or delivery. Any such defects of which KAC / KMC receives written notice within 1 year from the date of purchase by the original owner, will be remedied by KAC / KMC without charge.

https://www.knightarmco.com/returns-repairs