Another Kart Conversion magazine thread

[Grifo]

I've read a lot of discussions on various forums about magazine interchangeability for .22 conversion kits, but nothing that really specifically clarifies all the options for the Kart Conversions. And, are all Kart .22 conversions equal in mag handling? (not likely?)

Here's what I think is the case, but please clarify or correct me. In particular about which ones will lock the slide back on last shot:

Best choice, if you can find them: Kart
Second best: Colt Ace, but not Ace II (and there are multiple variations of the old Colt mags, are they the same?)
GSG: Work but might need sanding down the rear of the followers, might or might not lock back on last shot?
TripleK- might need tuning, but I've had mixed luck with TripleK over the years, so I'm shy about them.
Are the Sig mags the same a GSG? One thing I read indicates the older Made in Germany ones are OK, the newer SigUSA ones are not. ?
Colt/Walther German made do not work
Any of the polymer ones (including Kimber, Advantage, Promag* are to be avoided).

Marvel sells shims to modified GSG steel mags. Is that something to consider? Their standard mags are poly, I've read that none of the poly mags work well?
Are Nelson mags any different from Marvel?

Any additions or corrections to the list?

*(I've been told Promag is an acronym for Please Remember Our Mags Are Garbage)

[Grifo]

I think the Browning magazines are poly. What about the Mauser 1911-22 mags?

[Drawman623]

Kart mags do seem best tho cost and availability can be issues.
The Colt .22 mags with stamped floor plates have proven reliable feeding and actuating the slide stop for hold-open.
Ive also used unstamped mags, listed as from the supplier of OEM Colt on ebay… sketchy but they fed and locked the slide back consistently. Where these mags failed was that they didnt want to seat properly. I had to push hard to hear the click of the release button. I cannot say if they were triple K’s but they didnt perform as well as the stamped Colt mags.
I have not considered any other mags to offer opinion.

[Drawman623]

[Kp321]

I have been using Nelson plastic mags with my Nelson conversion every week for 5 years with zero problems. Don’t knock plastic magazines till you give them a good test. I do use the metal base pads that Larry Nelson offers from time to time. They add enough weight to drop free and they have a good chance of landing base down when dropped. You don’t have to tweak the feed lips every time they hit the ground like you do with the Colt or GSG mags. Believe me, I have used them all. By the way, GSG, SIG and Mauser are all the same animal. I have not handled the Colt branded 22 made by Walther so can’t express an opinion.

[Grifo]

I have been using Nelson plastic mags with my Nelson conversion every week for 5 years with zero problems.

Is the internal design and geometry of the Nelson the same as the Kart? I'm wondering whether your Nelson experience will translate directly into Kart usage.

[chiz1180]

I have been using Nelson plastic mags with my Nelson conversion every week for 5 years with zero problems.

Is the internal design and geometry of the Nelson the same as the Kart? I'm wondering whether your Nelson experience will translate directly into Kart usage.

No. Karts are different. Marvels and Nelsons share more commonalities but they also have some differences.

For what its worth, their is a reason that Karts are a minority on the firing line these days. Yes they can be quite good, but parts availability and the knowledge to troubleshoot them (and potentially make one off replacement parts) make them more of a collectors thing, as can be seen in the cost of the genuine magazines. 

I think they are cool, good luck in your search.

[RodJ]

Not sure if this info helps but i have an original metal Marvel mag supplied with my non/lock back Marvel conversion. I purchased a plastic poly mag from Marvel at the same time. It is flawless. Not a single hickup ever.

[Grifo]

I picked up three GSG mags. They do lock back on last round, and they all almost work- same issue with all three. Everything feeds nicely until the last two or sometimes three rounds. The nose of those last rounds pops up too high so they don't feed and the slide doesn't close. Exactly the same with all three mags.

Doesn't matter if I load five rounds or ten, it feeds fine until it gets to the last two or three, and has the problem.

Perhaps the rear feed lips are open too wide, or the mag springs are too week, or something else? Before I start tweaking and tuning the mags, I'd like an idea of what I should first focus on.

I tried polishing the inside of the feed lips on one of them with a 3000 grit stone, didn't make a difference.

[Froneck]

AMU modified the GSG magazines by adding an adhesive 1/8 think strip in the rear. I made a few for me Adam and a friend. I purchased 1/8" square brass from McMaster Carr and epoxied them to the magazine. Later I uses 5/32" square to increase width however I had to milled off about 1/32" after epoxy hardened from the top surface so it fit into the frame. So that the brass will not come off I cross drilled two 3/64" holes at an angle and inserted 3/64" brass rods coated with epoxy then squeezed in a mill vise that expand the brass so that when filed flat the pin was not visible.  That insure the brass squares will never come loose.

[Grifo]

AMU modified the GSG magazines by adding an adhesive 1/8 think strip in the rear.

Thanks, I see where the mag can shift and rock a bit without that. I remembered that Marvel sells GSG shims, I ordered those rather than hunting down the 1/8" square brass stock, I'll give them a try.

I also notice the follower angle is steeper on the GSG mags than on the Kart factory mags, and the end of the follower stops about 1/8 shorter, but I'll try the shims before I try modifying the followers.

[Froneck]

AMU might have used the Marvel shims, problem is they come loose after a while. AMU then covered the back side of the GSG magazine with epoxy. The 3/64" pins I mentioned might be over kill, 1/8" square works great. 5/32 allows you to fit the magazine to the frame however most of the additional 1/32" in height has to be removed. 5/32" width is OK.

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