Excessive headspace problem

GIshooter · February 01, 2003, 15:11

I just picked up a very nice STG-58 build on a Entreprise type I receiver. Had all the receipts for the compliance parts and it looked very nice. Took her home and thoroughly cleaned it. Had the bolt disassembled and checked the headspace. The stripped bolt and carrier closed on the Forster no-go gauge. Uh oh

Used my pin gauges and found that the bolt/carrier will close on a .265 with the go gauge in the chamber. It will NOT close on a .266. The question is: The gun has obviously been fired so do I have to calculate for setback? I'm thinking not. I believe a .265 locking shoulder is what I need. Am I right or really confused?

FAL guy · February 01, 2003, 15:22

Your Forster "GO" guage measures 1.630". so if you are shooting for headspace of 1.632" you need to subtract .002" from your measured pin. So .263" would be much better. I personally like 1.633" so I would use a .262" LS.

What size LS was in the rifle?

GIshooter · February 01, 2003, 17:14

The locking shoulder that was installed measures .261. It really swallowed that no-go gauge. A .263 sounds good.
Thanks!

FAL guy · February 01, 2003, 18:22

If you are using a Forster "NOGO", it is 1.634". A .263" shoulder should give you the "ideal" headspace length of 1.632".

Also bear in mind that 1.634" is still .004" from the Forster "Field" measurement, .006" from the Clymer "Field" measurement and the Nato maximum. So, while 1.634" will close on a "NOGO" you had a ways to go to the "Don't Shoot" point.

If you have a rifle close on the "NOGO" in the future, and you don't have a "Field" guage, apply a layer of 3M masking tape (.005") to the base of your "Go" guage and see if it will close on that. That could help you narrow down the actual measurement without buying guages that measure every .001"

February 01, 2003, 15:11	#1
GIshooter Registered FALaholic #: 4372 Join Date: Oct 2001 Location: Wisconsin for now Posts: 511	Excessive headspace problem I just picked up a very nice STG-58 build on a Entreprise type I receiver. Had all the receipts for the compliance parts and it looked very nice. Took her home and thoroughly cleaned it. Had the bolt disassembled and checked the headspace. The stripped bolt and carrier closed on the Forster no-go gauge. Uh oh Used my pin gauges and found that the bolt/carrier will close on a .265 with the go gauge in the chamber. It will NOT close on a .266. The question is: The gun has obviously been fired so do I have to calculate for setback? I'm thinking not. I believe a .265 locking shoulder is what I need. Am I right or really confused?

February 01, 2003, 18:22	#4
FAL guy Registered FALaholic #: 4319 Join Date: Oct 2001 Location: Oklahoma City Posts: 2,142	If you are using a Forster "NOGO", it is 1.634". A .263" shoulder should give you the "ideal" headspace length of 1.632". Also bear in mind that 1.634" is still .004" from the Forster "Field" measurement, .006" from the Clymer "Field" measurement and the Nato maximum. So, while 1.634" will close on a "NOGO" you had a ways to go to the "Don't Shoot" point. If you have a rifle close on the "NOGO" in the future, and you don't have a "Field" guage, apply a layer of 3M masking tape (.005") to the base of your "Go" guage and see if it will close on that. That could help you narrow down the actual measurement without buying guages that measure every .001" Last edited by FAL guy; February 01, 2003 at 18:25.

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February 01, 2003, 15:22	#2
FAL guy Registered FALaholic #: 4319 Join Date: Oct 2001 Location: Oklahoma City Posts: 2,142	Your Forster "GO" guage measures 1.630". so if you are shooting for headspace of 1.632" you need to subtract .002" from your measured pin. So .263" would be much better. I personally like 1.633" so I would use a .262" LS. What size LS was in the rifle?

February 01, 2003, 17:14	#3
GIshooter Registered FALaholic #: 4372 Join Date: Oct 2001 Location: Wisconsin for now Posts: 511	The locking shoulder that was installed measures .261. It really swallowed that no-go gauge. A .263 sounds good. Thanks!