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Old 03-08-2012, 11:43 PM
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Breechloader Breechloader is offline
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[3-2-2] Thermold
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Thermold magazines were developed by Master Molder in Wilson, South Carolina, and were "pitched" to the US military as a replacement to aluminum "USGI" mags, but the US military was unable to come to an agreement with the owner. Master Molder then licensed the design to the Canadian military, who manufactured a version of the Thermold 30-rounder as the standard-issue magazine for their military.
Thermold magazines are made from a dark gray polymer and have anti-tilt followers. They have several reinforcement ribs across the lower half of the mag body.

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[3-2-2-1] USA Thermold 30s
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The most common of the Thermold mags, these were made using DuPont Zytel, a fiberglass-impregnated plastic that is very strong and has a high melt temperature. Mold markings:v
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[3-2-2-2] Canadian Thermold 30s
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The Canadian military licensed the Thermold design, but did not use Zytel as the polymer, using a less expensive plastic as a substitute.
This was not a wise decision, and the Canadian military had problems as a result. The most famous problem was the feed lips melting when their ARs were fired for extended periods on full auto (especially with blanks), leading the Canadians to dub the magazines "Thermelts". The other common problem was the mags splitting or cracking in cold temperatures or when dropped. After Desert Storm, the Canadian military changed to USGI aluminum mags, which are now standard issue.

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[3-2-2-2-1] Canadian Thermold "Blank" 30s
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The Canadian military made some Thermolds with bright orange plastic as "blank only" mags. These are relatively rare, and are made with the same plastic as the standard Canadian mags.

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[3-2-2-3] Thermold/Master Molder 20s
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Master Molder made straight-bodied 20 round mags. These are US-made from Zytel and are the best aftermarket 20s. Mold markings:

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[3-2-2-4] Thermold 30/45
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Among the most unique magazine designs, the 30/45 magazines were designed with an extendable bottom section that would allow the magazine to be fully loaded to 30 rounds and stored (with the base extended) with the spring under minimal pressure. This allowed long-term storage of fully-loaded mags with no wear to the spring or the feed lips. They can also be loaded with 45 rounds when the base extended, though they shouldn't be stored in this configuration.
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