How do you head space a browning m2hb machine gun?

Answer 1

You don't. You headspace AND time the gun, because the timing changes with headspace and the headspace changes every time you change the barrel.

This is from the Picatinny Arsenal:

To headspace the weapon:

1. Raise the cover all the way up and retract the bolt.

2. Screw the barrel all the way into the gun, then back off two clicks. (To tell ya the truth, this is where most guys stop when they're in Indian Country.)

3. Charge the weapon and ride the bolt forward. Don't let it slam home; since the gun isn't loaded, if you do that you'll damage the bolt.

4. Retract the bolt about 1/16" and hold it there until you've used the gage.

5. Raise the cartridge extractor, push in the alignment guide and try to put the "go" end of the headspace gage in the slot between the face of the bolt and the rear of the barrel. There's a ring on it. If you can get the gage to go in all the way down to the ring, pull it out, turn it around and try to put the "no go" end in the same place. If the "go" gage went in and the "no go" gage didn't, you're done. If the "go" gage didn't go in, unscrew the barrel one click and try it again. If the "no go" gage went in, screw the barrel in one click. Keep doing this until the go gage goes in and the no go gage doesn't.

To time the gun:

1. Set the headspace.

2. Raise the cover, charge the weapon and ride the bolt forward.

3. Retract the bolt far enough to put the "fire" gage in. It goes between the front of the bolt and the back of the barrel, with the beveled edge against the barrel notches.

4. Remove the backplate and screw the timing adjustment nut down all the way. Don't take it off the timing stud, though.

(This is where timing this thing gets tedious...)

5. Retract the bolt far enough to remove the fire gage. Reinstall the backplate, retract the bolt, stick the fire gage in and try to fire the gun. It shouldn't fire.

6. Take the gage out, remove the backplate, screw the timing nut in one notch, put the backplate back on, the gage back in and try to fire the gun. Keep repeating step 6 until the gun fires.

7. Remove the gage, remove the backplate, screw the nut in two more clicks and put the backplate back on. Charge the weapon and ride the bolt forward. Insert the "no fire" end of the gage and try to fire. It shouldn't fire. If it does the gun has to go to the shop. If it DOESN'T fire, turn the gage back around and try to fire again. If it won't fire with the "no fire" gage in and will with the "fire" gage in, you're done.

Answer 2

To headspace a Browning M2HB machine gun, follow these steps:

1. Ensure the gun is unloaded and the bolt is in the forward position.
2. Use a headspace gauge to check the headspace. Insert the gauge into the chamber and ensure it fits properly.
3. If the gauge does not fit, adjust the headspace by either adding or removing shims from the barrel extension until the gauge fits correctly.
4. Repeat the process until the proper headspace is achieved. Proper headspace ensures safe operation and reliable function of the firearm.