Kinetic definition

We are shooters. We are manufacturers. We are KCT. This blog shares our experiences with gear, guns, ammo and more.

Check out our line of kydex holsters and magazine carriers! Holsters start at $35, and magazine carriers start at $25. Check out our ONLINE STORE.

If you have any questions or comments feel free to reply on the posts. Follow us on Facebook and Instagram!

Wednesday, March 14, 2012

Thermold 20 Round AR15 Magazine Review

 I found myself staring at the CDNN catalog at them, glancing at the price, and then wondering…  Are these any good?  I paid out the rear end for PMAGS, including one 20 rounder for T&E purposes, and I wondered, could a mag this cheap compete with a 20 round PMAG?
For a little bit of history, I got into shooting AR’s a few years ago, and decided to pick one up for myself.  When I got my AR, I experienced numerous failures with the standard GI-issue metal 30-round mags with the standard followers.  So, I did like anyone would nowadays, and went and got myself some PMAGS.  I immediately fell in love.  The anti-tilt follower was great, and the mags lighter weight meant I could carry more of them at the range without busting my much-abused back.  The 20-rounder was great for prone, bench, or positional shooting.  The only thing I hated was the price. 

Before I dive headfirst into this review, a bit of history from the company itself.

Thermold History
Thermold Magazines started in the 1960’s as a molded plastics injection manufacturer that served the automotive industry. It's founder, William Howard, was well known in his hometown of Wilson, N.C. as an innovative thinker who held many patents. Mr. Howard was also a big game hunter for whom making firearms more reliable was both a passion and a necessity.
Using a nylon resin called Zytel, developed by DuPont after World War II to replace metal in large-scale manufacturing, Thermold began producing weapons magazines that resisted heat and corrosion, and functioned with extreme reliability. Thermold magazines rapidly became the product of choice among military personnel, law enforcement officers and sport shooters around the world.
All of our products are proudly made in the United States in North Carolina. Today, many of the firearm industry’s largest and most prestigious distributors are once again able to sell the trusted line of Thermold magazines and weapons products.
"Time-tested quality and reliability. That's Thermold."
From the company’s website:

So, from some reading, we can find out a few basic facts: They were chosen by the Canadian military (I’m going to skip the jokes here), who had all sorts of problems with them, including feed lips melting under sustained full-auto fire, the shells cracking when they were dropped on hard surfaces, and in some cases, the feed lips becoming warped to the point that a sharp whack on the bottom of the mags would send rounds flying out of the top.

What the detractors fail to admit is the fact that the Thermold magazine design was bought and licensed by Canada, where they elected to not use the Zytel resin to produce the mags, and instead opted to use a cheaper plastic to produce the mags.  The magazines sold in the USA marked “Master Molder, Wilson, NC, USA, Law and Gov’t. Use only” are made of Zytel, and do not suffer from these issues.  So, much of the bad rap they’ve taken has been out of Thermold’s hands.

So, what do I think?
First impressions:
The mag feels cheap.  Cheap, like 80’s cassette tape cheap.  Like you could break them by squeezing or wrenching on them, let alone slamming them into a gun and flinging them aside in a dynamic environment.
So, to test that, it was off to the range.
My colleague and I took them out for a day of pounding.  We ran multiple courses of fire, and were not kind to them.  Even though we both had dump pouches, we took every opportunity to throw them around, toss them into the dirt and snow, and picking up mags out of a pile of snow and shooting through them.

Each time, we recovered the mags, banged a bit of dirt out of them, loaded them up, and took them back out for another spin, snow, dirt and all.  The mags performed flawlessly with hundreds of rounds ran through them in short order through both our guns, a 20” LMT upper, RR BCG with a CMMG lower, and a full CMMG 16” M4gery.  Both were DI guns.

Now, there are a few things to bear in mind.  The 20 round mags do not need an anti-tilt follower, as they feed straight (no curve like the larger mags) into the gun.  I have not run the 30 round mags yet, and though I have seen some people shoehorning a Magpul follower into them, I am a bit hesitant to place my trust in them.
Also, the price.  I think I paid roughly $15 for my 20 round PMAG.   Then I threw a Magpul Ranger Plate on the bottom.  Now, we’re looking at $18.  For one 20-round mag.
When I first ordered from CDNN, I got 4 mags for $3.99 each.  I took advantage of a special, and got 10 for $2.99 a piece.

So, if we do the math, I’m getting roughly 5-6 Thermold 20 rounders for the price of one PMAG 20 rounder with a ranger plate.  Now, if price was not an issue, I would take all PMAGs.  I really can’t think of a reason not to.  PMAGs are decades ahead of Thermolds because they should be.

However, since for most shooters, price is an issue, I am pretty happy so far with the Thermolds.  I am conducting a test on them where I’m using them to fill my bug out rig, where they will be kept in a damp trunk with a bunch of junk (If I told you I never clean out my trunk, it would be an understatement).
Each mag is clearly labeled, and will be tested for function or any flaws periodically, and then after a certain period (say, 6 months), the mags will be taken out and abused on the range to test their durability and feeding after a decent time in storage.

 Typically, I feel that the more firepower, the better, especially in a hostile dynamic situation.  I think most people would agree with that. That line of reasoning also says, “screw ergonomics, you should be bringing as many Beta C-Mags to the fight as you can.”
Well, that gets a bit expensive.  And if I want to have money for more ammo, training, and the newest widget to test, I have to save money somewhere.
So, if I ever need to go to my emergency stash (and I hope I won’t ever need to), I probably won’t be concerned with doing reloads to retention.  That means these mags are probably goners.  I can write off 6 Thermolds without much thought, considering the ammo they carry costs more than they do.  A small note:  stuffing paper towel in your mag pouches is a decent way to keep those 20-rounders from sliding too far into the pouch.  I ran Magpuls on them for a while, but finally swapped them to my GI mags as paper towel was cheaper, and I had a lot more of that than I had spare Magpuls. I'm also not sure I want to double up the cost of what can be regarded as a throwaway mag.  If it rains?  I've shot that way in the rain, the paper towels stay pretty dry with the mags over them.

UPDATE 11/15/12

All of the mags are still running.  I disassemble my .22 mags, GI mags, and C-Products mags every few months in a decent firing schedule (500 rounds of 5.56 in 3 months, 3k rounds of .22 in 3 months, more for both as needed), but have not had to take the Thermolds or PMAGs apart to clean yet.  The interior plastic on both polymer mag types seems to keep them running just fine. 

I've cleaned a few GI and .22 mags.  I haven't cleaned the Magpul or Thermold mags.

After I had replaced the green followers in my metal mags with Magpul followers, i never had an issue, but I would break down the mags every so often when they looked gummed up.  Some receivers have issues with them dropping free, especially when dirty.  Realistically, they are lightweight mags.  The receivers that have issues dropping them empty have no issues dropping them full.  Those receivers will also drop empty GI mags, so it seems to be an issue of the weight of the mag.  YMMV.


  1. This comment has been removed by a blog administrator.

    1. So far so good. The Thermolds have not caused one jam in over 3,000 rounds in three different guns. I like larger capacities, don't get me wrong. But the price I got these for, around $4 each. Makes me really feel like I got a deal, especially in these times. Since price is an issue, especially these days, I would pick up some Thermolds before I got anything else on the market for 20 rounders, except pmags. If someone offered me a GI mag 20 or a Thermold 20, I would take the. Thermold all day and never look back. Just my .02.

  2. Original comment by klindco, "Excellent report. I have similar experiences with the Thermold 30rd magazines, but the opposite with Mastermolder 20rd magazines...large number of failures-to-feed. I have, however, only tried the 20rd mags in a single rifle. The 30's have been in five different rifles with >2000rds fired.

    Please keep us posted as you continue your testing regime."

    We apologize, the comment was deleted on accident.