PDA

View Full Version : Head Space Question - using pin method


RL216
September 30, 2001, 22:43
I have built 3 Fals now using the sizeing pins method for head spaceing.

Thinging about this now, and wanting to make sure Im doing it correct, I would like to know if you push/hold the pin foward, to the rear or leave it alone while in the receiver checking head space.

Seems if you leave it alone there is potential for incorrect measurement due to the movement the pin has in the LS hole.

Radio
October 01, 2001, 01:01
No, you're perfectly okay to leave the pin alone. The way the locking shoulder thickness is gauged, and the way you're measuring with ZZ gauge pins or Casey's rods, is from the BACK of the receiver's locking shoulder hole, forward; NOT from the front of the hole, rearward. During headspace measurement, the pin/rod is being forced rearward against the back of the hole, exactly where it should be. Try it, you CAN'T push it forward, the closing of the bolt wedges it rearward. Also, consider the direction of chamber pressure the locking shoulder absorbs when a round is fired: REARWARDS. You're fine.

Congratulate yourself; even if incorrectly, you, sir, are at least thinking, which places you above a majority of the population.

--Radio

Dave1
October 01, 2001, 01:05
I tend to hold the pin to the rear and roll it a tad, helps the bolt drop. I also subtract .002 from the final pin size I.E. if the bolt closes on a go gauge with light (light) pressure, on, say a .260 gauge pin, I set the locking shoulder at .258. Works for me :D
Dave

RL216
October 01, 2001, 18:27
Guys,
Thanks for the reply. I understand now. This board has become a great source of information. Keep it up!.