View Full Version : First FAL build, LS' set back question?

January 19, 2009, 19:39
Hi all, this is my first FAL build by myself, beside the DS Arms I bought a long time ago.
I borrowed the LS gauge and Clymer Go/No-Go gauge from a friend. After removed the extractor, slide in the Go/No go gauge. The .253 is a no-no, the Go is way too easy and the No-Go will go in with a lot of thumb pressure.

I'd try the .254 pin the Go gauge will have a slight thumb pressure,but the No-Go is impossible to close the bolt. The largest gauge I can use is .258.

So, my minimum is .254 and maximum is .258. I read on Bandit's document I need to add .001 set back, so I need .255 LS. I had read somewhere on internet a while back that I do not need to add .001 for set back.

What is your suggestion for locking shoulders that I can shoot both .308 Win and 7.62 Nato?. Should I go with .254 or .255?
Thanks in advance.

January 19, 2009, 19:56
Calling ce....Calling ce...

L Haney
January 19, 2009, 20:21
I can't make that call for you, mebbe' ce will grace us and offer help. However. You did use some words that cause me concern. They are "a LOT of thumb pressure". The thing you are putting that pressure on is the headspace gauge. Check that last word. Gauge. This is a measuring device that should never have any real pressure applied to it. It will deform and no longer be accurate if it's treated like this. That is like using a micrometer as a C clamp. The fellow you borrowed it from should have told you this.


January 19, 2009, 20:56
Thanks guys. I hope Ce will chime in...:bow:

As for the thumb pressure, that's how the fellow who let me borrowed his gauges and Bandit described it on his website. I'm not using any metal device other than my thumb to push the bolt carrier to close the Go/No-Go gauge. I wrote it down in a piece of paper as " No thumb pressure, slight, a little bit, and a lot". I do respected another people's property and I know when and what kind of thumb pressure I do need to stop. After all, my spec. is .254-.258 = .004".

January 20, 2009, 17:29
Hi, NomoreARs, your testing methods are sound, and your progress is assured, just remember you are trying to achieve head "space", and too tight will always deny you satisfaction.

You need your space, man.

If you are building on a DSA receiver, of late .254 seems to be a common LS size, which is unusual in other manufactures, whose common size is around .260 or greater.

So by your calculations, I would say .255, with anticipation that this would be at the tight end of the spectrum, but close to a good general, practical headspace for both cartridges.

January 20, 2009, 18:21
CE,thanks so much for your advice. Yes, it's the DS arms receiver. I will go with .255 then. thanks again.