IMPORTANT: This information is strictly for informational purposes only. None of us are engineers, metallurgists or even machinists. We are strictly amateurs and this just happens to be what we have done for our own use. Modifying any weapon, ESPECIALLY blank adapting one, is extremely dangerous. Pressures can range up to 60,000 PSI or even higher. Variations of aperture size accuracy, recoil springs, weapon maintenance, and even basic weapon usage can create an extremely hazardous situation in one weapon when the same settings function correctly in another. Basically, do not attempt anything mentioned herein without first consulting a qualified gunsmith or an engineer much more knowledgeable in weapon modifications.

M1 Carbine Blank Adapter Aperture Sizes

For Updates Contact: Drew Ballard
Initial information compiled by Dave from Gopher Munition Works, edited and arranged by Chris Guska

M1 Carbine Blank Adapting FAQ
Blank Adapting the M1 Carbine

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BFA Type	Manufacturer	Size	Drill Size
1.) Military Surplus			(Functions)
Notes: With this adapter, since it is non-adjustable, it is indicated if it functions.  This adapter can be drilled and tapped for a set screw. This adapter will only fit on M1 carbines with milled front sights.	Atlantic Wall Blanks
	Blanksguys (Satterfield)
	Gopher Munitions Works Blanks
	Ketchum Blanks
	Swanson Blanks
	Norwegian Red Plastic		Yes
2.) Threaded Barrel Set Screw	Atlantic Wall Blanks	5/32	0.156
Notes: This is the true "Hollywood" in barrel type adapter, the OLD Norwegian red plastic blanks sometimes take 1/8 - 0.125 to cycle.	Blanksguys (Satterfield)	5/32	0.156
	Gopher Munitions Works Blanks	5/32	0.156
	Ketchum Blanks
	Norwegian Red Plastic	9/64	0.140
	Swanson Blanks	5/32