ATF Caliber Conversion Guide
Below is the ATF's Caliber Conversion Guide that is used to review tax stamp applications. This is also a great reference to use when trying to apply for a tax stamp, while using the ATF's eForm website. This information is taken from the ATF Form 4 5320.4 Standard Operating Procedures Guide from the National Firearms Act Division and is the conversion guide that the National Firearms Act Division (ATF) uses when reviewing tax stamp applications for individual applicants, gun trust applicants and corportaion applicants.
|
17 Cal |
.172 In |
4.36 mm |
|
20 Cal |
.2045 In |
5mm |
|
22 Cal |
.22 to .223 In |
5.56 mm |
|
23 Cal |
.228 to .230 In |
5.84 mm |
|
24 Cal |
-243 to .244 In |
6 mm |
|
25 Cal |
.251 to .257 In |
6.35 mm |
|
26 Cal |
.263 to .264 In |
6.5 mm |
|
27 Cal |
.277 In |
7.03 mm |
|
28 Cal |
.284 In |
7 mm |
|
29 Cal |
.298 to .300 In |
7.35 mm |
|
30 Cal |
.306 to .313 In |
7.5 to 7,65 mm, 7.62 mm |
|
303 Cal |
.331 In |
7-65 to 7.7 mm |
|
32 Cal |
.320 to .323 In |
7.92 to 8mrn |
|
33 Cal |
.338 In |
8.6 mm |
|
34 Cal |
.338 to .348 In |
8.8 mm |
|
35 Cal |
.358 In |
9 mm |
|
357 Cal |
.357 In |
9 mm |
|
375 Cal |
.375 In |
9.5 mm |
|
38 or 380 Cal |
.355 to .358 In |
9 mm |
|
40 Cal |
.400 to .413 In |
10 mm |
|
41 Cal |
.410 to 416 In |
10.4 mm |
|
42 Cal |
.423 to .435 In |
10.7 mm |
|
43 Cal |
.430 to ,435 In |
10.4 mm |
|
44 Cal |
.429 to .430 In |
11.2 mm |
|
45 Cal |
.451 to .452 In, .455 In |
11, 11.4, 11.5, 11.75 mm |
|
47 Cal |
.475 In |
11.9 mm |
|
50 Cal |
.500 to .515 |
12.7 mm |
|
28 Gauge |
|
14 |
|
20 Gauge |
|
15.6 |
|
16 Gauge |
|
16.8 |
|
12 Gauge |
|
18.5 |
Thanks to u/Smart_Slice_140 on Reddit for requesting and ultimately recieving the ATF Form 4 5320.4 Standard Operating Procedures from the National Firearms Act Division. His FOIA request of the Standard Operating Procedures reveals a lot of valuable information.
You can view his original post below or view the currently posted .PDF here.
Public Interest FOIA National Firearms Act Division Standard Operating Procedures for NFA Applications
byu/Smart_Slice_140 inNFA
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