PDA

View Full Version : What went wrong with this headspace?


Bullet
September 17, 2001, 18:28
I check for headspace on a Go-Gauge using a .264 gauge pin (actually using casey elliot rods). Its not tight, the bolt just drops into place. A No-Go gauge will not close on a .264.

I install a .264 LS and a Go-Gauge will not close. So, I recheck everything and determine that a .264 LS is needed. However, with a .264 LS the bolt will not close on a Go-gauge.

I remove .003 off the locking sholder, re-install and now the bolt closes on a Go-Gauge. Then checked to see if the bolt closes on a No-Go and it don't. So, now I'm ok.

What happened? Did I miss something?

This is my second Fal build. The first headspace went fine.

kotengu
September 17, 2001, 18:37
Maybe the way the round shape of the pin does not account for the square shape of the shoulder? Just enough to make a difference?

FWRA
September 17, 2001, 20:18
Originally posted by Hammerhead:
<STRONG>I check for headspace on a Go-Gauge using a .264 gauge pin (actually using casey elliot rods). Its not tight, the bolt just drops into place. A No-Go gauge will not close on a .264.

I install a .264 LS and a Go-Gauge will not close. So, I recheck everything and determine that a .264 LS is needed. However, with a .264 LS the bolt will not close on a Go-gauge.

I remove .003 off the locking sholder, re-install and now the bolt closes on a Go-Gauge. Then checked to see if the bolt closes on a No-Go and it don't. So, now I'm ok.

What happened? Did I miss something?

This is my second Fal build. The first headspace went fine.</STRONG>

George Gouger taught me a trick. When using the Elliot rods, after you get the proper closure on a Go Gauge, mark the area with a red felt tip pen. That way, if you do get distracted you'll always measure the proper step.

Not to say tha YOU did that. ;-)

Best Regards,
Mark Powell

Radio
September 17, 2001, 22:35
A good stab-in-the-dark effort by kotengu, but if it were true, EVERYBODY's headspace readings would be off since at least 99% of us use round gauges, either Elliot-type rods or MSC-type ZZ pins.

You didn't mention it but I assume the extractor was out of the bolt, and you used the carrier. Only two things come to mind: either you mis-measured in a fashion described by Mark Powell, or the locking shoulder was mis-measured (or incorrectly labeled). I don't think so but just to bring up the possibility, perhaps some kind of debris somewhere, chamber/bolt face/on a tool/etc.

Well, at least you worked your way through the problem. Building these rifles is a funny game, isnt' it.

--Radio

FWRA
September 18, 2001, 07:19
Here is a drawing originally posted by FXE awhile back that makes locking shoulder measurement easy.

Not that any of us has actually measured a LS the wrong way....... :-)

http://albums.photopoint.com/j/View?u=1022307&a=7540281&p=54256922&Sequence=0

Great drawing FXE!

Mark