Re: Lantac
Posted: Fri Jan 31, 2014 12:14 pm
In the case of the AR15 Milspec is a series of requirements laid down by the US military when they purchased the rifle.
Its NOT just dimensions on a drawing, its a list of materials, finishes, and treatments.
Its not got a lot to do with parts being made cheaply or with large tolerances either.
In fact its so costly to reproduce the original Milspec, Carpenter Steel, Heat Treat to correct Case Depth, Oil Quench, Refrigerate, Re-Grind, Surface Finish, Hardness test & HPT/MPI Test, Bolt in an AR15, that most companies simply cannot do it and make it profitable.
Each one of the above has its own MIL document outlining exactly what must be done and how.
This extensive spec has CNC shops spitting tea at the phone when they hear it.
This is exactly why 7075T6 Alloy must be certified to contain the correct blend of materials in order to fullfill the 'Milspec' requirement.
Without the certificate there is absolutely no way of knowing what you have bought, what grade or what quality.
You have no way of knowing the % Silicone content for instance.
To meet the Milspec for surface finish of a receiver the anodise must be Type 3 Hardcoat Class2 Black.
That spec for the anodising is covered in MIL-A-8625, here is an excerpt from that document:
3.4.3 Type III coatings. Type III coatings shall be the result of treating
aluminum and aluminum alloys electrolytically to produce a uniform anodic
coating on the metal surface. Type III coatings shall be prepared by any
process operation to produce a heavy dense coating of specified thickness on
aluminum alloys (see 3.7.2.1). Unless otherwise specified in the contract,
purchase order or applicable drawing, Type III coatings shall not be applied to
aluminum alloys with a nominal copper content in excess of 5 percent or a
nominal silicon content in excess of 8.0 percent. Alloys with a nominal
silicon content higher than 8.0 percent may be anodized subject to approval of
the procuring activity. Heat treatable alloys shall be in a temper obtained by
heat treatment, such as -T4, -T6 or T73, prior to anodizing.
As you can clearly see in order to fullfill 3.4.3 there is a requirement to 'know' the material composition of the alloy being treated in order to conform to the spec, as well as its temper, in this case T6.
Without the certification you have no way of proving you are within the specification.
As for discussing quality that effects performance then that's down to the quality of the bolt used, design of the receiver (will it flex and fit properly) and material choice.
Most importantly how the barrel was made and how it fits the receiver and under what conditions it was chambered, what lubricant was used and the quality of the reamer etc etc....
So unless you machine your receivers from certificated 7075T6 with Type3 Hardcoat Class2 Anodising, you simply ain't milspec or following the original design of the rifle.
We strive to make the best we can and to me that's about doing things right.
Hope that helps.
Its NOT just dimensions on a drawing, its a list of materials, finishes, and treatments.
Its not got a lot to do with parts being made cheaply or with large tolerances either.
In fact its so costly to reproduce the original Milspec, Carpenter Steel, Heat Treat to correct Case Depth, Oil Quench, Refrigerate, Re-Grind, Surface Finish, Hardness test & HPT/MPI Test, Bolt in an AR15, that most companies simply cannot do it and make it profitable.
Each one of the above has its own MIL document outlining exactly what must be done and how.
This extensive spec has CNC shops spitting tea at the phone when they hear it.
This is exactly why 7075T6 Alloy must be certified to contain the correct blend of materials in order to fullfill the 'Milspec' requirement.
Without the certificate there is absolutely no way of knowing what you have bought, what grade or what quality.
You have no way of knowing the % Silicone content for instance.
To meet the Milspec for surface finish of a receiver the anodise must be Type 3 Hardcoat Class2 Black.
That spec for the anodising is covered in MIL-A-8625, here is an excerpt from that document:
3.4.3 Type III coatings. Type III coatings shall be the result of treating
aluminum and aluminum alloys electrolytically to produce a uniform anodic
coating on the metal surface. Type III coatings shall be prepared by any
process operation to produce a heavy dense coating of specified thickness on
aluminum alloys (see 3.7.2.1). Unless otherwise specified in the contract,
purchase order or applicable drawing, Type III coatings shall not be applied to
aluminum alloys with a nominal copper content in excess of 5 percent or a
nominal silicon content in excess of 8.0 percent. Alloys with a nominal
silicon content higher than 8.0 percent may be anodized subject to approval of
the procuring activity. Heat treatable alloys shall be in a temper obtained by
heat treatment, such as -T4, -T6 or T73, prior to anodizing.
As you can clearly see in order to fullfill 3.4.3 there is a requirement to 'know' the material composition of the alloy being treated in order to conform to the spec, as well as its temper, in this case T6.
Without the certification you have no way of proving you are within the specification.
As for discussing quality that effects performance then that's down to the quality of the bolt used, design of the receiver (will it flex and fit properly) and material choice.
Most importantly how the barrel was made and how it fits the receiver and under what conditions it was chambered, what lubricant was used and the quality of the reamer etc etc....
So unless you machine your receivers from certificated 7075T6 with Type3 Hardcoat Class2 Anodising, you simply ain't milspec or following the original design of the rifle.
We strive to make the best we can and to me that's about doing things right.
Hope that helps.