1956 fit chart
Recall that there are at least two Perfect Fit size charts - although the "Perfect Fit" holster is generally depicted as a snap-loop holster.
The 1956 chart from Turneriver and as organized in the Bucheimer master thread below:
In 1956,
40 = 402 40F = 4” OFFICIAL POLICE, MARSHAL
However, the OP's holster does look like an auto holster -- so lets go with 11.
11 = 112 11F = .32 or .380 cal Colt Auto Pistol
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Bucheimer Perfect Fit holster size chart 1956
To the 2 digit number, add "B" prefix for black
== add "2" suffix for plain
== add "F" suffix for floral carved
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COLT AUTOMATICS - Perfect Fit holster
10 = 102 10F = .25 cal.
11 = 112 11F = .32 or .380 cal.
12 = 122 12F = .45 GOV’T & SUPER .38
14 = 142 14F = .45 cal. 4 ¾ COMMANDER
77 = 772 77F = 4 ½ “ WOODSMAN TARGET, SPORT or CHALLENGER
78 = 782 78F = 6” WOODSMAN TARGET, SPORT or CHALLENGER
81 = 812 81F = 4 ½ “ WOODSMAN MATCH TARGET
82 = 822 82F = 6” WOODSMAN MATCH TARGET
COLT REVOLVERS - Perfect Fit holster
20 = 202 20F = 2” COBRA, DETECTIVE SPECIAL
44 = 442 44F = 3” COURIER
44 = 442 44F = 4” COBRA, POLICE POSITIVE SPECIAL
54 = 542 54F = 5” POLICE POSITIVE SPECIAL
64 = 642 64F = 6” POLICE POSITIVE SPECIAL
40 = 402 40F = 4” OFFICIAL POLICE, MARSHAL
50 = 502 50F = 5” OFFICIAL POLICE, MARSHAL
60 = 602 60F = 6” OFFICIAL POLICE, MARSHAL
49 = 492 49F = 4” .357 MAGNUM, TROOPER
69 = 692 69F = 6” .357 MAGNUM, TROOPER, OFFICERS MODEL MATCH
52 = 522 52F = 5” NEW SERVICE
62 = 622 62F = 6” NEW SERVICE
43 = 432 43F = 4¼ SINGLE ACTION ARMY, FRONTIER MDL
57 = 572 57F = 5½” SINGLE ACTION ARMY, FRONTIER MDL
73 = 732 73F = 7½” SINGLE ACTION ARMY, FRONTIER MDL
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SMITH & WESSON REVOLVERS - Perfect Fit holster
23 = 232 23F = 2” CHIEF’S SPEC. TERRIER, CENTENNIAL
23 = 232 23F = 2”.32 HAND EJECTOR
23 = 302 30F = 3¼” .32 HAND EJECTOR
48 = 482 48F = 4” .32 HAND EJECTOR
26 = 262 26F = 2” .22/.32 KIT GUN
46 = 462 46F = 4” .22/.32 KIT GUN
25 = 252 25F = 2” .38 SPEC. MILITARY & POLICE
45 = 452 45F = 4” .38 SPEC. MILITARY & POLICE
55 = 552 55F = 5” .38 SPEC. MILITARY & POLICE
65 = 652 65F = 6” .38 SPEC. MILITARY & POLICE
88 = 882 88F = 4” K22, K32, K38 MASTERPIECE
89 = 892 89F = 6” K22, K32, K38 MASTERPIECE
32 = 322 32F = 3½” .357 MAGNUM
42 = 422 42F = 4” HIGHWAY PATROLMAN
52 = 522 52F = 5” .357 MAGNUM
62 = 622 62F = 6” HIGHWAY PATROLMAN
62 = 622 62F = 6½” .357 MAGNUM
83 = 832 83F = 8 3/8” .357 MAGNUM
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HARRINGTON & RICHARDSON REVOLVERS - Perfect Fit holster
31 = 312 31F = 6” Model 999 SPORTSMAN
28 = 282 28F = 2½” 922, 632 BANTAM
68 = 682 68F = 4” 922, 632 AND CAMPER
66 = 662 66F = 6” 922, 632 AND CAMPER
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HI STANDARD AUTOMATICS - Perfect Fit holster
16 = 162 16F = 4½” A, HA, B, HB
17 = 172 17F = 6¼” A, HA, B, HB
18 = 182 18F = 4½” D, HE, E, HE, SPORT KING, FIELD KING, OLYMPIC, SUPERMATIC
19 = 192 19F = 6¼” D, HE, E, HE, SPORT KING, FIELD KING, OLYMPIC, SUPERMATIC
13 = 132 13F = 4½” DURAMATIC
15= 152 15F = 6¼” DURAMATIC
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IVER JOHNSON REVOLVERS - Perfect Fit holster
28 = 282 28F = 2½” CADET, MODEL 68, MODEL 555
66 = 662 66F = 4” TARGET, MODEL 65, MODEL 68
68 = 682 68F = 6” TARGET, MODEL 65, MODEL 68
47 = 472 47F = 4½” SUPER SHOT, MODEL 844
67 = 672 67F = 6” SUPER SHOT, MODEL 844, ARMSWORTH, MODEL 855
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RUGER - Perfect Fit holster
92 = 922 92F = 4½” STANDARD AUTO
92 = 992 99F = 5” MARK I
93 = 932 93F = 6” MARK I
57 = 572 57F = SINGLE SIX
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OTHER - Perfect Fit holster
30 = 302 30F = 3 ½” ALL SMALL FRAME .32 CAL. REVOLVERS
91 = 912 91F = LUGER
95 = 952 95F = P-38
97 = 972 97F = BERETTA .25 CAL
98 = 982 98F = BERETTA .32 CAL