The Muster Rolls gave the Government and its local agents an idea of the defence capabilities available in each parish, listing what each man of service age could contribute in a military crisis. Because they were compiled on a local basis, their survival is patchy, but the National Archives at Kew have a good set of local muster rolls from 1535 (ref. E101/549/13). Unfortunately, I was unable to identify the Birker and Austhwaite entries from within the list for the huge parish of Millom, but here are the local entries I could find.
"Jaks" or Jacks, are very very tough jackets; not as good as armour or a modern flak-jacket, but still worth wearing. Similarly, sallets are light helmets.

Eschedalle & Wasdayllehede In the p'rycheyng of Saynt Bees
Edward Vecars
Ryc Vecars
Roberte Vecars
Ryc. Dyconson
Rog. Hartelay
Gyllberte Hartelay
Wyllm. Scharpe
Henry Hartlay
Wyllm. Hartelay
Alane Herteley
Wyllm. Nycollson
Nycolle Collynson
Thes Alle Be Byllmen hauyng Jaks & Sallets

Vellm. Vecars
John Vecars
Nycolle Dawson
John Daweson
John Thomasson
Ryc. Wyllson
John Wyllson
John Nycollson
Thomas Wyll'mson
Nycolle Tyson
Nycolle Dyconson
Rog. Hartlay
Nycolle Hartlay
Edward Hartlay
Gyll Hartlay
Roberte Hartelay
Wyllm Dyconson
John Steuynson
John Nycollson
Wyllm. Nycollson
John Coste
Robert Hunt
Roberte Staynton
Nycolle Hunt
Nycolle Wasdayll
Roberte Wasdalle
John Wasdalle
Thes Be Byllmen hauyng Jaks & Sallets & Bott vi hors Abyll amongs yayme Alle


The lordshype of Mu'kaster
Rog. Jakson
Wyllm. Trowgheton
John Trowgheton
Thomas Ffrear
Nycolg Robenson
Xr'ofer Atkynson
John Johnson
Henry Dyconson
John More
Ryc. Cowpland
Thes Ar Alle Bowemen wt. Jaks & Sallats

Ryc. Tubman
Ryc. Coppayg
Jake Trowgheton
Wyllm. Atkynson
Rog. Ffells [?]
John Jakson
John Harberte
Roberte Scharpe
John Wyllson
Thes Ar Alle Byllmen wt. Yare Jaks Salletts & horssys

John Coweplande
Nycolle Coweplande
John Ffrear
Ryc. Coppayge
John Tyson
Nycolle Scharpe
Wyllm Tomson
Robert Dyconson
John Tomson
George Atkynson
Wyllm. Tomson
John Rychartson
Thes Ar Alle yougmen wt. owt harnesse & horse


Thes Be the naymys of the townshipe of Byrtebe of the p'yshe of Monkkast'r
Roland Trogheton
Nycolle Troghton
John Kyrbbe
Wyllm. Wells
Ryc. Troghton
All thes ar Bowemen wt. horssys Jaks & Sallets

John Jakson
Roland Jakson
Thomas Syngyllton
Nycoles Cadde
Henry Cadde
John Trogheton
Wyllm. Bebe
Nycoles Robynson
John Bebe
John Robynson
John Jakeson
Roberte Jakeson
Steuen Jakson
Nycolg Person
Janno Trogheton
Wyllm. Cadde
Thes Ar All Byllmen Wt. horssys Jaks & Sallets