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 Differences between inch and metric?
1stID  [Member]
8/31/2006 6:21:27 AM EST
Would an experinced FAL hand spell out to us newbies the difference between the inch and metric FAL?

I assume the split comes from tooling used in the countries that made the FAL (UK - inch, rest of the world metric). What parts are different? How are the mags different, and, how can you ID each type? Are there any other accessories that are unit specific?

Thanks,
1st ID
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FALna45  [Member]
8/31/2006 12:23:12 PM EST
alot of differences. many subtle, others not so much.
as far as wether the receiver is inch or metric, it could be either or some of both if we're discussing century stuff. i'm not sure about the receivers they made, but some of their (metric) Imbel receivers had some of the inch cuts done to them.
the pertinent areas to check (besides external profile) are the cut for the mag (inch on left):

corresponding portion of mags (again, inch on left)

because the cut out is larger on inch guns, they MAY function w/ either pattern mag but sometimes the metrics will be sloppy and can cause feeding problems.
Commonwealth rifles have a folding rather than fixed knob on the charging handle, here are the cuts for the charging handle (inch on left, cut back to allow for the folding handle):

cuts for the tabs at the rear of the inch dust cover -sorry, i don't have a pic of that.
inch pattern rifles have a BHO which holds the bolt back only when YOU push it up while retracting the handle, not on last shot.
you can replace the short pin on these or the whole unit if you desire the last round hold-open.
the Commonwealth mag release is much different than the metric, extending the control surface out to the rifle's left. interchangeable to metric receivers with the (longer) inch screw to accompany it:

clockwise from top left are inch, metric, Israeli (my fav by far) & a tapco "Holland":

the Commonwealth selector is way oversized compared to a metric version also.
inch pattern flashiders employ a notched barrel / pin&donut arrangement whereas most metric muzzle devices just screw on (excepting a few lugged variants).

the Commonwealth pattern features an open eared gas (a few metric variants feature this, too) block that accepts a different type of front sight, a blade more than a post as on metrics. the Commonwealth line of sight is ~3mm higher than the metric, and employs a folding rear aperture not found on the metric pattern.
here are inch and metric gas blocks (inch on left)

the lowers, while interchangeable amongst upper receiver types as assemblies, have difference which preclude interchanging many internal components.
a quick way to check for lower type is the metric PG is fixed from it's underside by a nut while the Commonwealth PG is fixed by a bolt down thru the top of the lower. the buttstocks are quite different as the Commonwealth lower has tangs that accept the buttstock, whereas on a metric the stock or it's ferrule butt up against the lower.
sand cut features rarely encountered on metrics are the norm for the Commonwealth rifles' bolt carriers. as seen here:

differences you don't readily see are the washers employed in timing the Commonwealth barrel, and the 45* gas port as opposed to metric @90* to the bore's axis. i'm sure i missed something, but there's a start!

FALna45  [Member]
8/31/2006 12:41:30 PM EST
ok, here are selectors
metric

inch

i also forgot the gas regulator / adjusting nut on the L1A1 aren't threaded onto the gas block as are the metric. L1A1 on left:
pliftkl  [Team Member]
8/31/2006 4:25:17 PM EST
I know that I don't need to "tag" things anymore, but silently tagging without thanking you for that detailed response would just be wrong.
1stID  [Member]
9/1/2006 7:15:18 AM EST
Thanks for the info.
whatnow  [Team Member]
9/1/2006 9:00:28 AM EST
Nice post, another item are the trigger groups. Inch/metric are dimensionally slightly different. I believe they are interchangable in groups, not individual parts. The inch version uses a bushing that unitizes the trigger/sear assembly, make dissassembly that much easier.

Bill
patriot73  [Team Member]
9/3/2006 4:44:29 AM EST

Originally Posted By whatnow:
Nice post, another item are the trigger groups. Inch/metric are dimensionally slightly different. I believe they are interchangable in groups, not individual parts. The inch version uses a bushing that unitizes the trigger/sear assembly, make dissassembly that much easier.

Bill


Inch and metric trigger parts are not interchangeable. Inch trigger/sears utilize a slave pin to hold them together on the trigger pin which does make assembly easier. I took and old metric trigger pin and cut the length down to the width of the trigger. This way, I can push the sear/spring and trigger together with my homemade slave pin and drop the whole assembly in the lower and then tap the new trigger pin into the side of the lower which in turn pushes the slave pin right out and sets the new trigger in place.
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