KART .22 Conversion

[John Hash]

For many years, my Kart Conversion worked perfectly, but about ten years ago, it developed problems.  Feeding was the foremost problem, followed closely by light firing pin strikes.  I finally changed to Kimber magazines which cured the feeding problems, it seemed.  I tried Jagemann magazines for the hold back feature, and they seemed fine, too.  However the light firing pin hits persisted.  The barrel is a Marlin, like the other early Karts.  I thought it was a change in the ammunition.  Fred designed his conversions to shoot Remington standard velocity ammunition, but in the ensuing years, most switched to CCI SV.  I became suspicious that the problem was caused by insufficient closure, too.  I noticed a small peened area on the firing pin cover, so I filed off some metal there, creating a slant on the rear surface of the cover, hoping this would provide a more direct hammer strike on the firing pin.  We also rechambered the barrel with a standard .22LR Clymer reamer.  We ground a small chamfer on the loading ramp where it meets the lower lip of the chamber.  The light hits continued.  The Kart firing pin is a Colt Ace pin, or close copy,  I understand, and the critical measurement is from the shoulder to the tip.  My FP protrudes a bit farther than the chamber depth in the slide.

U

nlike the High Standard and S&W 41 which have a near contact type of firing pin, it is the inertial type like the 1911.  Now that Johnny Dworak is gone, God rest his soul, I have no source of firing pins.  I want to try a firing pin set up like the HS and Smith.  Does anyone know if an AR-15 firing pin is longer than the Kart firing pin?  It looks very similar.  By the way, my usual practice was to shoot the slow fire dry, but add oil after brushing for the timed and rapid fire courses.  Rubbing the ammunition for the 900 with oil seems like a good idea, too.  Until I get the Kart working reliably, I am shooting an HS 107 with an LSP aluminum sleeved barrel and a 30mm UD.  Your advice would be appreciated.  Thanks.

John Hash

jlh...@aol.com

[crhodesx]

Most problems with Karts stem from 2 to 3 general issues and blindly attempting solutions without a very systematic analysis can exacerbate issues ad infinitum.

First and foremost the locking rod must be tight.  I don't mean just snug, but damn tight.  As the Karts get older, the rod will tend to loosen up quicker and quicker.  This is the major cause for miss feeding,  light firing pin hit and balky operations. I've seen a couple that needed to be checked between the slow fire strings and the short line.   They can loosen up that fast.  Blue lock tite,  wavey washer under the "e" clip, and judicious preening of threads are some other solutions here.  

Second is the firing pin stop.  It will need to be carefully preened so that it is not just held in place by the firing pin spring.  You should need a punch to help seat the firing pin stop when reassembling.   A loose stop will absorbe a considerable amount of the hammer strike energy and result in light strikes, erratic velocities and resulting weak feeding issues, etc.  Then people start reducing the recoil spring poundage and create a whole other series of issues.

Other things follow like making sure the hammer strut is long enough that the hammer is still under some pressure, even at rest, preened bolt face, "modified magazines,  etc.  

I have modified firing pins by increasing the depth of the back of the pin step so it protrudes a little further above the face of the firing pin stop.  That's easier to do than finding a longer one. I did talk to a couple of people about making some slightly longer firing pins, but never got to follow through.

The hardest part to actually doing a good analysis of Kart issues today is finding a "virgin" magazine that some wanna be gunsmith haven't abused and molested to the point of making it a paperweight as far as helping the gun and not hurting it.

Anyway, a properly set up Kart should run perfectly with the old standard 5 pound recoil spring with most standard velocity ammo or the 4.5 pound with really weak SK stuff and a unmolested magazine (even a pristine Ace mag). If it doesn't, its generally some of the above stuff and not magazines.  

Just my 2 cents

Sent from my Verizon, Samsung Galaxy smartphone

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[KC]

Another possibility is the chamber is leaded up.  I'm going to assume you don't have a ding in your chamber from dry firing.  If you do that is the first thing that needs to be taken care of by swaging it out.  Now for the drop or plop or whatever you would like to call it test.  Hold the barrel muzzle down and drop a live round into the chamber.  If it does not fall all the way to the rim and then fall out of its own weight when you turn the barrel upside down you need to clean the chamber.

Take a .25-.27 cal bore brush and clean JUST THE CHAMBER.  Do not run that brush into your barrel.  Continue until that round drop and falls out freely.  If you're still having issues after that, Cecil's recommendations are spot on.

[Gregg Gammie]

I had similar problems with mine.  Dave Salyer worked wonders.