Torkmag displayed their new prototype 40rd magazine at SHOT.

It's 8.8" tall, as opposed to 9.5" for a regular 40rd PMAG:



By using a dual spring system, they are able to reduce the amount of 'spring space' at the bottom of the magazine, allowing for a shorter overall magazine.



The use of coil springs was famously employed in experimental 50rd magazines in the Vietnam war:

https://taskandpurpose.com/50-round-magazines-navy-made-seal-m-16s

It looks like an interesting design. I don't think I've ever seen them for sale anywhere I usually shop, though. I have a Torkmag Glock mag, but I've only found one vendor who sells them. They don't have much of a market presence.

Looking forward to trying that out.

I have 3x 50rnd versions all work 100% what annoys me is none of the big guys like MAC,SOOTCH, MR GUNS N GEAR Havent done a review on these or the schmeisser 60rnd mags?

How long is the PMAG 30rd? Looks like you can get 40rds in about the same space as a 30rd PMAG.
I don't do much run and gun yet, but if I did, a shorter 40rd would get my attention. The dual springs look like it distributes force on the follower better as long as the coil spring holds up over time.

Usually new mags don’t do anything to peak my interest, but Torkmag, you have my attention...

i have some of their older ones, seeemm ok, havent run many rounds through them.  i wanted them cause they had thin ribs, or no ribs inside, so could fit fat shells in there single stack. or that was my plan. dont remember if it turned out....

I’d like to see a 30 rounder closer to the length of a 20. Better for bipod use.

In terms of Coil Springs/ constant force spring, they've been in use for like 30 years in high cap 10/22 mags such as the Buttler Creek 25rd.



The mags jam because .22lr plus dicey mags. But the springs themselves hold up fine.

There's no reason why a centerfire coil sprig mag won't hold up.

I can't count how many tape measures I have had to throw away or have seen discarded on the ground at construction sites. Wonder what a little sand added to it would do.

I wonder how long they can be left loaded and if their sides will bulge like some AK mags have been known to do when left loaded.  Also will their feed lips break and dump rounds like the PALM mag did.

Most nailguns use constant-force coil springs in their feed trays, and I've fired more nails through a single nailgun in the last couple years than all of my guns combined...
Tape measures use clock springs, btw.  Similar but not quite the same thing.

That's a very encouraging data point. I had no idea nail guns used CF springs.

Could we get a CF spring quad-stack @ around 45-50 rnds the same length as a 30?

Torkmag makes a 35rd mag thats the exact same height as a 30rd magazine, and a 50rd thats less then 1" taller then a pmag 40.



Thats with their hybrid dual spring. A true CF spring mag, with no coil spring in the base, would be even more space efficient; they could probably get 50rds into a PMAG 40 length mag, or a ~8" tall 40rd mag (30rd pmag is 7.25").

Notably, the Vietnman prototype 50rd magazine was a real, CF spring only mag. As we can see, 50rd's was about the length of a modern 40rd magpul:


CF springs would also allow new styles of 'drum' magazines:

https://www.thefirearmblog.com/blog/2012/05/17/ultra-compact-ar-15-ribbon-spring-concept-magazine/

Interesting.  35 round mags would put the Army's 210 rnd standard load in 6 mags instead of 7.

Funny you mention that.

The AUG uses a 42rd magazine, thats actually 0.25" shorter then the PMAG 40rd / same height as a 30rd AK magazine. I always though 42rd was a weird capacity.

Turns out, 5x42 = 210rds exactly. 1x in the gun, 3x on the chest, and 1x on the belt, would provide a full 210rd loadout.

Ideally, I'd like to see a 42rd CF spring magazine. Based on the available space in the AUG mag, that would probably be around 8.25" high, only +1" over a standard 30rd mag.

Don't really want to go longer than the standard 30 until I get some experience w/ an AR in the BREN configuration.  Have that new 60 rnd coffin mag to play w/ for that.

I've pretty much standardized on 40rd mags. They seem long at first, and then you just kinda forget about it. And then 30rd mags start to look short.

A standard AK mag is 9" long, so it's not like the 7.25" length of a 30rd AR mag is set in stone. The original STG44 used a 10.375" mag.



Frankly, I think the M16 should have started its life out as a 40rd magazine.

(Standard 7.62 mag 20rd, 5.56 weights 1/2 as much as 7.62) + (M16 designed for FA) + (our enemies use 9" tall 30rd mags) = 40rd master race.

@spydercomonkey are you affiliated with TorkMag? I have a couple 35’s and a couple 50’s in the stash. Haven’t loaded and shot em yet but they seat/drop well. Seem to be well made mags.

Seems cool

I wish - free mags

No, I've just been keeping an eye on them since they debuted on TFB a few years back. Being a gun nerd, I'm always interested in new / renewed technology, so novel highcap mags are right up my alley. At the time, I never purchased one, as the 35rd didn't offer enough capacity boost to be worth it over $8 30rd pmags, while the 50rd seemed a bit too long to standardize on.

I had kinda forgotten about them, and then wandering the basement area of SHOT this year, I came across their new 40rd prototype. I was excited, as thats the exact 'goldilocks' mag I had hoped they would produce. Well, ideally a 42rd the same length, but thats just my OCD.

I’d love to try one with the .458 SOCOM or other .458 based cat.
Their web site shows the 50 loaded with .458 SOCOM and holds 18 rounds.  When the 40s come out I'll have to try a couple.

In the early/mid 90's, I had a couple of Eagle International clear plastic AR15 magazines that used a constant force spring. From what I remember, they fed reliably...but the mag themselves were delicate and both broke when dropped on the ground during mag changes.

Here's a good video with a clear Torkmag, showing exactly how their CF spring system works:

https://youtu.be/SSiHl6nwb0Q?t=41

I've had very positive experiences with my Torkmag 50rd mags. I LOVE them. They work perfect in every gun I've tried them in, including full auto, EXCEPT the Steyr AUG.

For some reason they don't play well with the Steyr AUG, like as in NOT AT ALL, don't even waste your time trying, I already have.

Again, every other gun, full auto, semi-auto, all good to go.

They are easy to load too. Long as hell though.

And, they are only like $30 man!

I've already committed to ordering some of these new 40rd mags and am pretty excited about it.

I also like the fact that the original 35rd torkmag is the same length as  aregualr 30rd USGI. That can be nice for certain pouches.

tsh77769

Just a couple things. I note a few posts early on about the coil spring looking like a potential problem. I'm presuming people misspoke, and that they think the constant force spring looks like the week point--since coil springs are what all other magazines use. I agree that grit seems like it could be a real issue if it got in a CF spring.

There is some speculation that an all CF mag could be functional, including the comment about Ramline pistol magazines, which I find really interesting. Here's the reason that an all CF spring mag doesn't work--usually. With a possible exception, but we'll get to that.

The reason that linear, stacking coil springs work better than CF is simply that you have a linear, stacking force pressing down--the ammo. Let's say every complete 5.56 round weighs 100gr. So you want every 1/3rd or so of an inch you push to impart an additional ~1/4 ounce of tension in the spring. By the time you have a full 30, you've added a half a pound (over a pound for 300BLK subs) of pressure on the spring, so you want the coil spring to be pushing back with about that same amount of extra pressure. Each round you feed from the mag lowers both lessens the weight on the spring and relieves pressure on the spring in roughly equal amounts. This allows the final round to feed roughly the same as the first.

But what about all that extra spring length you have to wedge under the floorplate when you re-assemble a mag? It seems like we want to have a spring that goes up from zero.
The pre-compression is important for speed. That is, if we put in a spring that stacked with only a little more pressure than the weight of a round, the time for the bullet to seat completely against the feed lips would be comparatively very slow. Like, pulling off 0.1s splits would be a no go.

The pre-compression that allows for speed of the stack to rise is one of those material science dark magicks that companies likely spend a lot to figure out (like, how do harmonics of bouncing off the lips change with material, for example) and then specifically hold on to as a trade secret. CF only magazine would complicate the math a bunch. If you start with a standard mag with, say, a four-pound compression when empty, you know that on a full mag you have about nine or 10 extra ounces of extra pressure pushing back against nine or 10 ounces of new weight. So each round feeds about like the one before it. The first feeds roughly like the last.

But when you start with four pounds of pressure on a CF only mag, adding a half pound of ammo doesn't increase your spring pressure to four-and-a-half, if effectively means you are pulling your first round to feed with only three-and-a-half. If you try to counteract this effect by starting with five pounds of constant force on empty, then your first round feeds at four-and-a-half and your last at five. That's a 10% difference in force, which is significant--and more significant the lighter the cartridge.

I like the spring hybridization--probably because I sketched it on the back of an envelope before I knew Torkmag was a thing. The advantage is the setup requires less pre-compression. So each round added to the stack creates only the pressure it needs to return, while the pull on the nose-end of the cartridge lends a consistency to the velocity needed to pop the stack up for the next round to be properly stripped off. No need for pounds of pre-compression means fewer coils, which gives the option of a notably shorter mag.

The possible exception to the rule is that unusual U-shaped digital mock up above. By virtue of having half the stack around the bend, the weight would be equalized in either leg when full. So the most net weight that would ever effectively need to be pushed up would be half the rounds.


So, it's kind of an answer to an unasked question. Because the standard coil-only mag has been perfected several times over, I don't think I'd consider hybrid mags it in a critical-situation rig. Still there is appeal in more go-bang in a shorter package for range time. Apart from that, I'll stick with large capacity mags of the coffin variety that use coil springs to great effect. And occasionally modern drum mags which are equally surprisingly compact.

Best posts from a new member I've read all month, thank you.  Engineer?

Hey, bb. That would be a no. Specifically, not by training; by passion, maybe.
I'm just here to learn and foster learning. Just like everyone else on the internet claims to be.

You are most welcome. My thanks to you for the comment. And taking the time. It means a lot from someone of your position and tenure here.

When it comes to pushing rounds in a mag, inertia probably plays more of a role than weight.
If you can outrun a vertical mag, you could probably outrun the same mag with the gun on it's side.

The TL;DR is that coil springs naturally have the quality of dynamically adding force the more force that's required in a gun magazine, while a CF spring has the net reverse force curve.


I mean, I'm not gonna swear to anything. Just using the evidence at hand plus the bits I understand.
in most cases, only the most trained and practiced operator or competition shooter would risk outrunning a too-light sprung mag in semi-auto. But imagine how much gravity their opinion would carry if they lost a match because they pulled the trigger and the no-bang was a F2F due to a weak spring. That social media tirade could kill a brand.

I do want to make sure that we don't disregard that weight (well, mass) and inertia are entangled, since you mention it. Hence my comment about "and more significant the lighter the cartridge" regarding bouncing off the feed lips. The relationship between energy and weight is linear, but energy and speed is non-linear, as lots of shootists have learned either the easy or the hard way.

For example, my 200gr 300AAC subs @ 1000 fps have 444 ft*lb of energy at the muzzle.
Double the weight to a 400gr 458SOCOM @ the same speed, easy math--you double the energy to 888 ft*lb.
If instead you push that original 200gr slug to twice the speed, though, now the result is 1,776 ft*lbf, or four times the energy it had at 1000 fps.

The mag spring has to contend with that same sort of graph for momentum. Rapid acceleration across a pretty wide range of potential loads. A stack of lighter rounds is more likely to bounce off the lips because the spring has to be tuned to push the heavier as well--more speed with less weight equals more overall force, and not as much inertia to dampen the bounce. The heavier rounds are going to bounce less, more inertial and less net force, but getting the stack started moving upward is slower going. It's a square relationship. So as I mentioned prior, a hybrid gets you shorter mags, but the math needs greater attention. Compared with a coil only mag, a pure CF spring mag would have unduly complex physics. Probably workable for a single weight of cartridge, by why live life with that kind of restriction.

KE is 0.5*m*v^2 after all ....

One of the reasons I want to experiment w/ an upside down binary AR.

Can't wait for the video with chopinbloc and a former Spetsnaz with their respective rifles, checking functionality in a Gravitron to see how each performs in "zero-G".
For science.