22 .40 rounds in a 140mm magazine

[CHA-LEE]

Out of utter jealousy of the STI/SVI guys who are able to get 22 .40 rounds in their "Special" 140mm Limited mags I did some fiddling with springs and followers to see if I could get 22 rounds in an EAA 10mm mag with Henning's 141 base pad. I found that a Bolen follower with a 9 coil spring allows you to jam 22 rounds into the mag. Yes it does take some serious persuasion to get the last round in there, but its in there. I have test fed this through my gun on the bench and it seems to feed fine when I manually rack the gun. The next time I go to the range I am going to give it a try in live fire to make sure that it works. My only worry about it is that the spring is so short and gets so collapsed when you jam 22 rounds in the mag that I am not sure if will have enough spring tension to properly support and present the last few rounds in the magazine as you shoot. I also don't think that you will be able to keep the mag loaded to maximum capacity and have it sitting around for long due to the spring losing its tension while being fully collapsed. I usually have to pull the spring out and stretch it out after loading it up to 22 rounds. You will probably have to load it up and then go use it immediately. I will have quite a bit of testing to do with it to make sure it actually works and is reliable. But being able to get 22 rounds in the magazine is a win in its self.

[al503]

Not a spring expert but stretching the spring out without controlled heat/duration/length will do more damage than not.

[CHA-LEE]

al503> Oh I am sure stretching the spring out isn't good for it either. Just as over compressing the spring damages it as well. But I don't have an easy bake oven at the range to reheat/reshape the spring after I have over compressed it. Using the spring once then throwing it away is also not very viable. The challenge here is the stack up height of the spring its self due to the diameter of the wire. If a smaller diameter wire could be used which still produces the same spring rate would be best because you could have more coils and less chance of over collapsing the spring. I know that some companies make coil springs out of Titanium and since that metal is stronger than spring steel the diameter of the wire can be less while producing the same spring load weight. But getting custom Titanium coil springs would probably cost more than the whole mag its self. You could also do a stacking Wave spring but you run into the same challenge of R&D and cost. I am not willing to spend a few thousand dollars in R&D trial and error on custom springs to see what works. Maybe Henning would be up for that project?

[XRe]

Just curious - if you're cutting it down to 9, aren't you taking the "magic" collapsing coil out of there? Couldn't you basically get the same thing w/ a Grams spring? Or is there a 9 coil Bolen spring I'm unaware of? It sounds like you might be a little short on spring tension at the top... but I'd be concerned more about it pushing up a whole stack of rounds quick enough than I would be about the last few. Might be a high maintenance magazine.... but if it works all the time (even if you have to baby it), might be worth playing with

[CHA-LEE]

XRe> I forgot to mention the spring type I am using for this. Its a Grams spring. So the lower coils are all the same size and don't fold into one another as it collapses. I just took a standard 11 coil spring and started cutting off coils until I could fit 22 rounds in the magazine. I think you might be right on the slower speed of raising the rounds though. It does seem slower than a standard setup so it might cause jams when shooting fast. All I can do is try it out and keep fiddling with it to try and make it reliable.

From a competitive standpoint NOT having a 22 round mag when others do is a disadvantage on the few stages that require it.

[sinnsyk]

When I shot the double tap last year they had a 24 round stage where Manny took a miss by only shooting 23 rounds as he could load 22 + 1. He won the stage and was over a second faster. There was no time to reload. It was a sick high hit-factor.

I wouldn't go to 9 coil, but 10 could work if you only use the mag when absolutely necessary. Because of that stage last year I thought of making a slightly larger basepad with an even thinner floor. You could do that and shave more off the back of the magbody. The pad could also be made out of steel which would allow to make the pad floor probably only 0.020" and hold up. Just reducing the floor would give you 0.030" plus making the pad 0.020-0.030" is doable if you accept shaving more off the rear of the magbody. This was something "i had to do", but forgot. Also I don't know how many will be interested in such a pad as it's pretty extreme.

let me know, we could possibly make a few in steel that's longer with a thinner floor and 22 is absolutely achievable.

[CHA-LEE]

Sinnsyk> I am all for it. Make up some steel base pads with a thinner floor and I will buy them.

[Jeff686]

Is the official measured length for a loaded or unloaded magazine?

Can't you cut the bottom of the the floor plate all together? All you need is a feature to capture the _END_ of the spring, then the rest of the spring could protude out the bottom a little...

I also always wondered if we could rig an external coil-spring (like the 10/22 big sticks), and add width instead of height. You would need some kind of combo spring system, since the coil would not fit inside the mag well.

[bikerburgess]

Jeff

it goes in the gauge unloaded and I believe it has to sit against the back of the gage under its own weight.

Mike

[CHA-LEE]

If the mag can be unloaded while measuring the length that opens up a whole new world of possibilities.........

You could have a two piece base pad that is spring loaded so that its held together with no rounds keeping the whole mag at 140mm in length. Then as you put rounds in it the bottom portion separates making it longer and easier to load the rounds. Kind of like a telescoping mag pad. But I am sure that USPSA/IPSC would ban the use of such a mag because you could easily have big stick capacity with something like that.

[Skydiver]

You could have a two piece base pad that is spring loaded so that its held together with no rounds keeping the whole mag at 140mm in length. Then as you put rounds in it the bottom portion separates making it longer and easier to load the rounds. Kind of like a telescoping mag pad. But I am sure that USPSA/IPSC would ban the use of such a mag because you could easily have big stick capacity with something like that.

Probably, but it'll be good while it lasts... however long it takes a new ruling to be published.

And also the apoplexy of people's reactions would be fun to watch.

[CHA-LEE]

I gave my 22 round magazine a try at least 10 times on Sunday and it worked flawlessly. I also didn't take the spring out and pull it apart to stretch it out to see how many times I could use it before it failed to feed and much to my surprise, it never failed. The last few rounds were super loose though so I am not sure if I was just lucky that it didn't jam or what. But I am happy to report that I now have a reliable 22 round .40 mag to leverage in matches

[sinnsyk]

Having a magazine that collapses to legal length (flexing) is already been done and found unsportsmanlike. Of course that road has been traveled ;-)). Just before or during the World Shoot in Ecuador my buddy in Canada had the pad & mag setup that way, but got shut down by IPSC. I was up there training prior to the match and it was a pretty neat idea. And the feeling was exactly as expressed here... neat until it gets caught. So then what's the point ? I believe the point is to compete sportsmanlike and though bending the rules to our liking I agree with officials that it could be seen as cheating.

My machinist is running H-141 pads and I told him to make some that are 0.030" longer with a 0.015" thinner floor. We looked at making the pads from steel, but the machining time and tooling cost wouldn't be worth it. If we can get 0.040" - 0.050" more space just by creating a slightly more extreme pad the cost of gaining another 0.010 - 0.020" is huge in comparison.

You would need to file more off the rear of the feedlips for the mag to fit the gauge, but it'll work. I'll have the pads soon along with a re-supply of regular H-141 pads.

:cheers:

[High Lord Gomer]

I gave my 22 round magazine a try at least 10 times on Sunday and it worked flawlessly. I also didn't take the spring out and pull it apart to stretch it out to see how many times I could use it before it failed to feed and much to my surprise, it never failed. The last few rounds were super loose though so I am not sure if I was just lucky that it didn't jam or what. But I am happy to report that I now have a reliable 22 round .40 mag to leverage in matches

Are you running the extra power mag springs?

http://speedshooters...egories=Springs

OOPS! Just realized I wasn't in the M&P forum.

Ignore EVERYTHING I say!

Edited April 2, 2010 by High Lord Gomer