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AR15.COM
4/30/2008 4:55:23 PM EDT

Quoted:

Q: Why doesn’t the AR-10 use FAL Magazines? They’re cheap.

A: The FAL magazine suffers from technical weaknesses when applied to the AR-10.

Mark Westrom was attracted to the low price and easy availability of the FAL magazine, and studied it and others thoroughly. The FAL magazine is very effective in FAL rifles. Unfortunately, it suffers a number of characteristics which make it very much less suitable for use in an AR-10.

The FAL magazine is not a stand-alone feed device. It merely contains cartridges and presents them to the feed lips in the rifle. The actual, functional feed lips are machined into the upper receiver. The feed lips protect the magazine’s lips from damage. The machined lips are in close alignment with the chamber and tolerate poor quality magazines. Because the AR-10 requires the magazine lips to feed, the FAL magazine was not determined to be tough enough for an AR-10.

Next, studying of the movement of the cartridge during feeding revealed that the M-14 magazine closely matched feeding from the early ArmaLite 10 magazines, and was thus very suitable to feeding up the barrel extension of the AR-10.

The feed from a FAL magazine was very much different and obviously required dramatically ramping the bottom of the barrel extension in a way that cut deeply into the lowest locking lug. This reduces not only the strength of the barrel extension, but the symmetry with which it accepts recoil loads from the bolt. The M-14 magazine thus allows a stronger action in the AR-10 than use of a FAL magazine would.

Unless modified by cutting an M16 style magazine catch slot in it, using the FAL magazine requires the action of the rifle to be built considerably longer than the action of the AR-10. The magazine itself is longer, and the magazine locking and bolt catch mechanisms behind it required more space between the trigger pocket and the barrel. The whole action thus must be longer, as well as the carrier. Both weight and length are increased.



how do you respond to this RRA
5/1/2008 4:33:03 AM EDT
[#1]
Two different approaches to building a .308 AR-style rifle.  They upscaled a .223 platform to get where they are and to use the mags they use, while we designed a new rifle that uses the mags we use.   The "technical weaknesses" cited are as they would be applied to the AR-10. as stated, not the LAR-8.
The LAR-8's receiver IS longer, as is the carrier, but as a result the LAR-8 does work reliably with most FAL and L1A1 (metric and inch) mags.   We acknowledge that not EVERY FAL/L1A1 is going to work with every LAR-8 (just as they don't necessarily work with every FAL) but at $5-$8 a pop for mags in good shape, you can buy 10, keep the nine (or even all ten)that work and resell those that don't work at the fun show and have 3-9x (depends on how much you pay for AR-10 mags and FAL mags) the mag capacity for the same price.
Steve/RRA


5/1/2008 6:54:38 PM EDT
[#2]
dont get me wrong, as soon as I see a chrome lined 16" barrel you will be getting my money.

but your response doesnt seem to answer their statement that the feed ramps must be cut deeper into the locking lugs in order to feed from an FAL mag. or are you saying that you lengthened out the ramp, so that it slopes at a lower angle, over a longer distance (thus not into the locking lugs of the barrel extension)?
5/2/2008 4:57:20 AM EDT
[#3]
Again, what Mark Westrom stated was as it would apply to his AR-10 (his subject being why the AR-10 doesn't use FAL mags), not our LAR-8.
Alot of folks early on read what he wrote to say that we had to leave off a lug.  That could not be further from the truth.  It took quite a while, a lot of work and a bunch of photos (that are probably archived somewhere on ARFOM) to dispell that misperception.
His discussion is really about his rifle, not ours.  Our receiver is longer.  Our bolt catch and mag release are different.   Our bbl extension isn't missing anything...neither is the bolt.  
Steve/RRA