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ccarnel
January 05, 2009, 16:11
I finally got the time to put together 3 FAL kits from GPG that I had laying around but had a few questions about barrel timing and headspacing.

I bought the timing rods from Court in FL here on the boards and followed the instructions to a "t". On all 3 rifles the front and rear rods lined up perfectly and I even verified with a bubble level as well as an angle finder on the rods. (All three builds are on DSA type II receivers). Two rifles are para's and the third is a standard fixed stock build.

I then went on to headspace all three rifles yesterday and when attaching the lowers and looking through the rear site it appears that on 2/3 rifles the front site seems to be canted ever so slightly to the right (when looking through the rear sight). Two of the rifles measured .253 and one .256 for proper headspace using the forester go/no-go gauges and sizing pins.

Pretty bummed as I thought I was pretty meticulous in getting the timing rods lined up.

I guess my questions are:
1. Is it possible that it's just an optical illusion that the front site base seems canted? Should I just assemble the rifles as is and test fire to confirm alignment?

2. Should I try to re align/torque the barrel and recheck headspace BEFORE ordering the appropriate locking shoulders, or will .5 degrees of alignment/barrel indexing either way not make much of a difference with headspace?

3. Anyone experience a similar problem using the rod alignment method?

ce
January 05, 2009, 17:08
There are other indices you can use to determine timing.

Screw in the gas tube nut and observe its relation to the divot in the barrel.

Check the relation of the barrel flat to the receiver flat on the left side.

Shoot it. It would be a good thing if it was canted to the right, because screwing it in further is infinitely easier than screwing it back out.

Shoot it.

brownknees
January 05, 2009, 17:08
You might be seeing "spring back"
If the allignment isn't dead right you need to go back & get that fixed as it'll change any headspace measurements if you do it later.

ccarnel
January 05, 2009, 18:24
I did use a little bit of anti-seize on the threads.. could this have caused any of the "spring back" that has been mentioned?

brownknees
January 05, 2009, 20:43
I doubt it. It'll probably have reduced it a gnats nut hair.
Springback is a release of tension on the components & wrench handle when torque comes off the system, anything reducing friction should have helped, not hindered.

W.E.G.
January 05, 2009, 21:54
Originally posted by ccarnel
...will .5 degrees of alignment/barrel indexing either way not make much of a difference with headspace?

about 0.0009"

kev
January 06, 2009, 00:21
Barrel threads are 16 tpi(threads per inch)

One complete turn equals 1/16"(0.0625").

1 degree equals 0.0625/360(0.0001736").

Works out to about 6 degrees rotation for .001" change in headspace. Anything less than that wouldn't be worth worrying about. You're way less than 6 degrees from tdc or there wouldn't be any question about retorqueing. Go ahead and put in the shoulders and testfire. If you need to wiggle the barrel a little later, you won't change anything.

ggiilliiee
January 06, 2009, 13:36
ya just used the wrong tool .hehe .
probably what happened is during the machining of the rails .one got pushed up out of parralel to the other .only take a couple thou at the rails to throw the rod waaaay off at the top of the legg

datum must be rite before ya measure anything ...

http://community-1.webtv.net/ggiilliiee/BARRELTIMINGTOOL/

and the gig rail widening method will stop all the bullet nose ramp whackin oal changes too ..:wink:

http://community-1.webtv.net/ggiilliiee/ICOMEINPEACE/

ccarnel
January 06, 2009, 14:11
ggiilliee, that looks like another great alignment tool. How do I go about sending some cash your way to get one of these?

ggiilliiee
January 06, 2009, 14:46
that can be arranged .shoot me a PM ...i gotta go out for a while but will be back later today ......

dont get me wrong .
..Courts rods are greaat ..ya just have to be carefull what ya set them on ...(rails ) and know they are both 90 to the rifle

a depth check of the rails with calipers and a machinist square againts the receiver side and part of the horizontal profile as a stop will give you an idea of where they are ...doesnt take much to push them out of place with a dull e-mill .. :)

johnny.308
January 09, 2009, 11:53
Another quick check is to assemble the gas system and drop the piston through to see there are any restrictions, rubbing, or non-alignment. It should drop through the hole in the receiver and move back and fourth freely without any alignment issues.