Some info I found.
This is to help people new to the FAL family of rifles to determine what parts on their rifle are Inch and which are Metric. Century is notorious for mixing parts on their rifles. Most rifles are built from kits, and may have a mixture of Inch and Metric parts. I am not an expert and if any info is incorrect please tell me. If I have used a picture of your rifle in this post and want it removed, please also let me know. I have gathered this info from the Files and other sources.
First we will look at the typical features of Inch and Metric rifles.
Most parts are interchangable between the two types of rifles, the main exception is the lower reciever parts. The internals of the lower recievers are not interchangable. The buttstocks also are not easily interchanged. An Inch type selector may be modified to fit an a metric lower. Upper and lower recievers are interchangable. I.E. an Inch lower will fit on a Metric lower and vise versa.
The magazines are different also
An Inch upper reciever will accept both inch and metric magazines, howerver the metric mags may not function with 100% reliability. A metric reciever will take ONLY metric mags.
How do I tell if my upper reciever is Inch or Metric?
Magazine cut for front lug
Cocking handle rail, Note inch has been cut off for folding cocking handle
The other difference is in the cuts on the top of the reciever. An Inch dust cover has tabs and therefore the Inch type reciever has cut-outs for these tabs.
There are some Metric recievers that have been modified with Inch type cuts.
Not all metric rifles have closed ear gas-blocks. An inch pattern gas block will have the gas port drilled at 45 deg to the central axis of the barrel, and on a metric gas block the gas port is perpendicular to the barrel and accessed by removing the front site. A metric front site is a post type, and an Inch front site is a blade type.
Metric bolt hold opens and mag releases are different from Inch style, but are easily interchanged. Most if not all of the bold hold opens on Inch pattern rifles have had the pin that is pushed up by the mag follower ground off. This is quite easy fix and costs less than $0.50
I hope this will help any who wonder what type of parts were used to build their rifle.
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