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.

[Grifo]

AMU might have used the Marvel shims, problem is they come loose after a while.

Local hardware store had the 1/8" brass in stock, so I did one of the mags. It definitely locks in better and feels more solid, but it didn't fix the problem of the last couple of rounds popping up.

The GSG follower is (I'd estimate) about 10 degrees steeper than the Kart factory follower. I shaved the followers down 5 degrees (not enough plastic to shave more than that), and now they feed beautifully. I tried with two mags, the one with the shims and one without.

Now to solve the problem of light primer strikes, I'm experimenting with different springs...

Attachments

GSG mag with shim.jpg You don't have permission to download attachments.(339 Kb) Downloaded 2 times

[Froneck]

I didn't intend to imply the shims would fix the feeding problem those it might. I also find it odd that the follower angle was a problem since it worked OK until the last 2 rounds. Would think that the angle issue would be a greater problem with a full magazine since the spring will be compressed more. I think I would try making a shim to fit in the magazine on the bottom of the spring to increase spring pressure.
 One thing I found and I think I posted in another topic is the firing pin surface was quite wide and long in Nelson conversions. I had failure to fire with a main spring in my Ball Gun. I had an older version, Adam a newer, mine didn't have an angle on the bottom of the pin, Adam's did so I assume there was an upgrade/improvement. Having an Optical Comparative I could measure the width of the flat. I compared it to the AW-93 and MatchGun2 firing pins and it was quite a bit wider. I then stoned the side angle to reduce the width equal to the other pins mentioned plus in my pin I added the lower angle. I then used the lightest main spring EGW had and failure to fire ended.

[Grifo]

I think I would try making a shim to fit in the magazine on the bottom of the spring to increase spring pressure.

I did that first. Since it was only the last two, sometimes three rounds popping up, that seemed the obvious culprit. I have a 3d printer, made various shims up to one that compressed the spring 12 mm (about two casing widths). That didn't make any difference in feeding. See attached photo. Changing the angle on the followers seems to have done the job.

Firing pin surface is round, I need to look closely, I think it might be slightly domed.

I got various springs from Wolff, I'm experimenting swapping one thing at a time. I have a rather heavy mainspring in it at the moment, when I tried the 17 and 16 pounders it wasn't ejecting and/or cycling. I just swapped firing pin springs, I'll test that tomorrow, if it doesn't solve the light strikes I'll try changing the mainspring again.

Beautiful pistol, eventually I'll get it reliable with standard velocity .22 ammo.

[Froneck]

On my Nelson and the firing pins I purchased from Nelson the end of the pin is not round. I can make a photo of one pin I purchased from Nelson. The pin in my conversion was not angled at the bottom, it made a straight indent dam near to the center of the rim. As I mentioned the width of the flat on the wedge shape was wider than those on the other .22 pistols mentioned. If you search the posts you can find the post I did about the pins a while ago.

[Grifo]

Almost there. I actually have two complete Kart slides and barrels, a 5" and a 6". I'm focusing first on getting the 6" functioning and reliable with CCI SV. I also have an extra mainspring housing and spring from ebay, and a bunch of springs from Wolff.

Both firing pins are round. The pins themselves are tapered cylinders, so if the tip had any sort of wedge or indent there is no way to index it so it always aligns the same. The tip is flat with a beveled edge.

Anyway, I'd tried the original firing pin spring from the 6" and the Wolff firing pin spring. Today I swapped out and put the spring from the 5" in the 6" and that gave better dents in the casing, but still mostly light strikes. I then swapped mainsprings, I was using the mainspring from ebay put in the 17# from Wolff. Ran 55 rounds, just 3 light primer strikes (all fired the second time) and one failure to feed... and all but one of those problems was with the same factory Kart mag, so I'll study the mag and compare to my other factory mag.

When I get a chance I'll try the 16# Wolff mainspring, but I'm 95% there now.
And the GSG mags function beautifully with the angle changed on the follower.

,

[kc.crawford.7]

Have you tried the plop test on both barrels? Could be a dirty chamber and those light strikes are the firing pin pushing the cartridge fully in. Have you tried thumb cocking the hammer and refiring the ones with light strikes?

[Grifo]

Have you tried the plop test on both barrels? Could be a dirty chamber and those light strikes are the firing pin pushing the cartridge fully in. Have you tried thumb cocking the hammer and refiring the ones with light strikes?

Thanks. The 5" passed the plop test, but that's not the one I've been working with. It's been perhaps 200 rounds of LRN since I cleaned the chamber well on the 6", and it failed the plop test. I cleaned it and it passes now, I'll try to test it out tomorrow.

They were mostly firing on second strike when I'd thumb cock.

Got a feeling I'll need to give this a good cleaning after every range trip.

[Froneck]

I know you can't wedge the pin like a Nelson and others because nothing will prevent rotation. Increasing main spring might require reducing recoil spring. That could increase your problems. Maybe reducing the firing pin spring weight will help. Did you try during slow fire to insure the slide is completely closed? Not sure if Kart firing pins are available so changing the shape may not be a option. Could they be the same as a 1911 pin of a modified one?  Possibly making a pin and altering the angle on the end, point remaining the same yet the sides have a less angle. Do you have photo of fired and failure to fire case rims?

[Grifo]

I tried the 16 lb mainspring, ran 36 rounds through four different types of ammo. About half didn't go boom on first strike, but all but two did on second strike. I checked in between each one and it was going fully into battery. It is cycling and feeding well.
I have a 17 lb mainspring, that is what I was using the other day before I scrubbed the chamber, and two mainsprings of unknown weight. Maybe I should try ordering an 18 pounder... Or look into different firing pin springs?

I had compared my two firing pins, they are the same length.

From a sandbag at 25 yards, Eley Target grouped just under 7/8", CCI SV at 1".

[8eightring]

I had to install a higher magazine catch in a Springfield Armory frame to get GSG magazines to work in my Kart. After that it was all good except some ammo didn't have enough energy to run the slide all the way back.

[Froneck]

One thing to check, is the face of the chamber side of the barrel 90° to the frame? What about the slide face? However if they were parallel the angle wouldn't really make a difference if it were small. Might want to check face to chamber.
 I put my Nelson on my Ball Gun frame, I too had failure to fire on first hit, second hit fired. As I mentioned I put shot case on my Optical Comparator from AW-93 and MatchGun. Width of the strike was .040" Length .045". Nelson was .050" X .090" the pin diameter, sides radiused. I filed the width to .040" and put a 45° angle on the bottom so it was .050" long. Usd EGW 14lb main spring and get 100% fire rate. Later I ordered firing pins from Nelson to use in my Homemade conversion. End of pin width was .035" straight sided, no angle on bottom so .090" long. Case rim is only about .025" wide, you might want to try making the angle on the end so there is less side resistance as the pin enters the notch in the case. I know as I previously mentioned you can't put flats on the sides of your pin but changing the radial angle will lower the entry resistance and increase impact pressure. Length of flat sides on Newer pins is about 1/16".

[Grifo]

[RoyDean]

Grifo,

I'm guessing that is an older model Aimpoint creatively mounted on your gun.

Did it come to you in that pale blue, or did you somehow get it painted?

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