DEPARTMENT OF THE TREASURY
Bureau of Alcohol, Tobacco and Firearms
Washington, D.C. 20226

JUN 18 1998            
F:FPD:FTB:RAT
3311

Dear Mr. :

This refers to your letter of March 31, 1998, in which you ask about permanently attaching a muzzle device to various firearms.

A muzzle device, such as a muzzle brake or barrel extension, which is attached to a barrel by means of welding or high temperature silver solder having a melting point of at least 1,100 degrees Fahrenheit, is considered to be part of the barrel for purposes of measurement.  A seam weld extending at least one-half the circumference of the barrel or four equidistant tack welds around the circumference of the barrel are adequate for this purpose.

A firearm having a muzzle brake, cap, or barrel extension permanently attached by those same methods to cover the threads on a barrel, would not be considered to have a threaded muzzle. Please note, however, that any muzzle device or barrel extension which functions as a flash suppressor or grenade launcher would still constitute one of the qualifying features of a semiautomatic assault weapon as that term is defined in 18 U.S.C. section 921(a)(30(B). Industrial adhesive products are not an acceptable method for permanently attaching a muzzle device.

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Mr.

We trust that the foregoing has been responsive to your inquiry. If you have further questions concerning this matter, please contact us.

Sincerely yours,

[signed]

Edward M. Owen, Jr.
Chief, Firearms Technology Branch

Quoted:
Just want to know the legal way to convert a preban threaded barrel to accept a muzzle break pinned and welded  ?