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Old December 06, 2002, 23:17   #1
FALaholic #: 6054
Join Date: Apr 2002
Posts: 683
Dan Coonan Receiver Hardness Test Info


I contacted Dan Coonan for information about his receiver that FAC sells. This is the response he sent me. This might answer some of the questions that more than a few of the members here have about them.

There is information concerning the hardness of FAL Receivers manufactured by Imbel, DSA, Enterprise, etc. in a post dated Oct. 31st in the Review Form that I believe was started by Meepers when he reviewed a U.S. Armament Receiver.

I hope this helps.



We have done a fair amount of hardness testing of various FAL type receivers. The only receivers that should be used as a benchmark or standard are the Imbel commercial and contract (military) receivers and the various receiver remnants
found on rifle kits. The most common of these receiver remnants is the front end section; still attached to the barrel. We have just recently
seen center sections and back end sections from L1A1 and G1 rifles. Here is the scoop in a nutshell: All Imbels and contract (military)
receivers are SOFT!!!!!! LESS THAN 20 (TWENTY!) Rockwell 'C' Scale, with the EXCEPTION of the UNDERLUG/LOCKING LUG AREA. The Underlug/Locking Lug area has been spot treated by either induction or resistance heating to the critical or transformation temperature and quenched ; no tempering. The result is a hard spot, about 57 Rc, blending to 18 -20 Rc within 1/2 inch radius. Our best engineering analyses of this spot treatment (and we sent our head engineer on an all
Ireland Pub Crawl BEFORE he kissed the Blarney Stone!) is this: They wanted the locking lug something better than dead soft - around 25-30
Rc. So they spot hardened and quenched. By eliminating a Draw or Tempering operation, they saved BIG BUCKS! - and that's the only reason
it's 57 Rc and not 25 Rc.
Our parts are Normalized, Hardened, Drawn - three different heat-treat operations - to 25 to 30 Rc and then fully machined in this hardened condition. We have tried other methods. This is the most predictable. DSA receivers measure 25 -30 Rc anywhere and everywhere. Some people
claim their receivers are 'rock hard' - they fail to claim they have rocks in their head!
As an added note, this is an extremely hard part to check accurately. We have been forced to SECTION parts and prepare them for hardness
evaluation. The inclination is that the parts measure softer than they are due to part movement while testing, and the heat-treater making them
harder because of the lower readings, This can be SO MUCH FUN!!!!
I have more to say, but I think I'll have a pint of Guinness before the Blarney wears off!
Thanks for giving me this opportunity!
Dan Coonan
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