Why are most .22LR pistol mags limited to 10 rounds?

[MT_Bear]

I just received my Sig 229R conversion kit, and I already have a Kimber Rimfire, and it occured to me that majority of the .22LR pistols and conversion kits have 10 round magazines. Certainly my Sig 229s with a capacities of 13 rounds (9mm) and 12 rounds (.40 S&W or .357 SIG) could have a potential capacity of 20-30 rounds of .22LR.

I understand that some states, like Californicate, limit magazine capacities to 10 rounds, but neither my Kimber or my Sig were manufactured there.

So why are the .22LR mags usually only 10 rounds?

Thanks for any info.

[Shawn Knight]

Double stack 22s have feeding problems because of the rim and the 10 round limit makes it easier to fit the firearm the conversion was designed for. I know there is a bunch more room in some magazines but since the 22 operates with such light springs to get the mag springs tuned to work well with more rounds would make for constant maintenance.

Too much pressure on the slide will decrease functioning and too little won't push the top round up fast enough for the slide to strip it from the magazine. it is just easier to make them 10 rounds. magazines like the 25rd 10/22 mags use a different spring system because of the room available in the magazine design. The constant wind flat springs in those magazines give even pressure but take up a lot of room that might not be available in a pistol sized magazine.

[MT_Bear]

Thanks for the info Shawn!

[wanderer]

MT, the kimber 22 mags can be taken out to 12 rounds and still seem to work ok, i have taken mine to 14 but as shawn said the light spring wont lift the rounds fast enough.

take the plug out and make a replacement from plastic or wood, about 1/2 inch should give the 12 and mine are down to 1/4 inch, it feed ok with 12 loaded but with the 1/2 inch plug will give a little more tension on the spring. dont use the origional part cause you cant get new ones if you mess it up.

[Intel6]

The magazines for my .22 LR conversion for my H&K 91 are 20 rds and are what I call semi doublestacked. The rounds do not completly double stack but the mag body is wider so the rounds slightly offset. The spring is small diameter wire and pretty light but it works like a charm.

Neal in AZ

[Kyle O]

I've got some 15 rounders for my mountain eagle compact.

edit=

the spring is a circular spring that sits flat against the back of the mag, with a coil under the follower. (think: yo yo that you fish with.)

I've never seen this design anywhere else. Might have something to do with it being a double stack.

Edited April 21, 2009 by Kyle O

[Fireant]

My Tactical Solutions 10 round mags will hold 15 rounds and still function perfectly(when fed good ammo).

[Shawn Knight]

I've got some 15 rounders for my mountain eagle compact.

edit=

the spring is a circular spring that sits flat against the back of the mag, with a coil under the follower. (think: yo yo that you fish with.)

I've never seen this design anywhere else. Might have something to do with it being a double stack.

Some of the Butler Creek and Ram-line 25 round mags for the 10/22 use a spring system similar to this. Springs that are like this can exert the same amount of pressure from full to empty.

[MT_Bear]

Thanks again to all for the info. Now if I can just find a way to couple my Ruger 10/22 magazines to my Kimber, I can really burn the ammo!

[LPatterson]

When Bill Ruger designed the MK I back in the 50's he said 10 rounds were enough and it duplicated what was being loaded in the High Standard which was Ruger's main competition at the time. In '57 the unit pistol team used all High Standard Target models.

[Chris_Andersen]

I removed the plastic stops from the inside of my Kimber rimfire and they hold 15 now and still function flawlessly.