View Full Version : Magazines: how to fix THERMOLDs

July 07, 2001, 16:26
Well if anyone cares! I recently posted some questions about thermold mags for my Israeli FAL Heavy Barrel. I broke down and bought two very expensive mags, and they didn't even function. This post is for anyone that cares about fixing them.

Mine didn't feed or eject correctly! Nor would they strip the new round from the mag very well, it kept passing over the round.
I noticed that the mag fit was Very snug, Too snug! The top surfaces of the mag had irregular surfaces, stopping the mag from seating flush to the bottom of the receiver. I carfully filed the top flat and somewhat square to the sides of the mag, so I would have a good seat.

While I was playing around I noticed that the mag was cocking away from the mag release side of my New Imbel receiver.[The mag was not sitting straight up and down in the receiver well]. It seems the Thermold mag has a stengthening rib set on an angle that matches the angle of the receiver Right side. When the mag is inserted all the way in,this rib contacted the right skirt of the magazine well, and while it's pivoting going to lock up, it pushes on the bottom of the this skirt, Thus cocking the mag to the side. A lot!

This also pulls the mag away from the underside of the mag well, creating a large space between the two. This made the bolt miss the cartridge! I then used a .010 thick piece of paper to use as a feeler gauge for my fit up. I first filed the Stengthening rib to fit the receiver and so it would not cock the mag any more. Then I used my Feeler Gauge to fit the top of the mag correctly [ or at least my type of correctly]. I didn't touch the locking lug, only the top surface of the mag. I filed the top till my gauge gave me a space between the receiver and mag. This method also gave me a slight bit of looseness in the mag fit.

I tried my fitted mag out and it functioned correctly. I then repeated this procedure on my second mag and it is also now useable.

Pardon my spelling errors. If anyone is interested I hope this helps!

[ August 07, 2001: Message edited by: EMDII ]

July 07, 2001, 16:28
Can I send this to the FAQ? :o

July 07, 2001, 16:33
Ted if that is the place for it! Go ahead!


July 07, 2001, 18:21
On the Way!

Listen to the Dark Side-
FAL: the Force

GySgt D
August 03, 2001, 08:35
I used to think that Thermold magazines were the cat's meow, due to the fact that in the 80's they were a curiosity and they looked cool. However, after fifteen or so years of actual use, their shortcomings have become obvious. I have several for a mini 14 that if they are fully loaded will not function, due to excessive spring force. The M14 mags will not reliably actuate the bolt hold-open device, and the only magazine related malfunction that I ever had with an AR was with a thermold mag. Seems as though the sharp tips of SS109 rounds snag on the soft magazine interior.

August 03, 2001, 10:55
At least one of my two AR15 Thermolds doesn't hold open on the last round. I'll hold the bolt back only if you manually retract it over an empty mag. I rarely fire the AR15 anymore, so haven't tested the other one. I bought these from tapco about 6mo ago, so I don't know if I'll be able to return them or not. I was waiting to try the other mag. Now I don't want either of them.

Are the Orlite mags any better? I don't like the GI aluminum much. Too fra-gi'-le (must be Italian).


August 05, 2001, 16:22
BryonF, You will be pleased with the Orlites. I had one for my AR15 and it was VERY used when I got it but never gave any problems. Material is super slick and tough.