Wynn's Mag-Na-Ported P40 BLOG updated

[TucsonMTB]

I managed to straighten that out using sandpaper and a dowel.. or round file... LOTS of filing and polishing.

I've heard it said that a man with that kind of experience starts with the dowel the next time.

[wyntrout]

It was like a red-hot knife touching butter... just psst and stuff was GONE... just like using a DLT polishing wheel on the polymer stuff... at 20-30K RPM it just smokes away... vaporizes.

I'm impatient and too reckless... at times.

Wynn

[TucsonMTB]

Yep! It took me a while to learn to reach for the hand tool first. It's amazing how much easier a file or carefully wielded piece of wood covered with sandpaper is to control.

Patience? . . . we don't need to stinkin' patience . . . just ask my wife.

[wyntrout]

Well, I used sandpaper on a plastic "dowel" to briefly sand the chamber "ceiling" and "floor" a bit. I used 320 grit and then 1200 grit without going nuts. Then I polished the chamber with emphasis on the ceiling and floor.

I still had the same problem... rounds c0cked in the chamber. When I slowly pull the slide back, the base of the cartridge seems to slip under the extractor and center itself over the striker pin hole with the follower pressure. It's like the base of the cartridge is getting caught without completely going under the "claw"... until a little pressure is remove by pulling the slide back without losing contact with the base... then click, it pops over and up... and it's centered, easily chambered by letting the slide go. This happens almost every time on the fifth or sixth round of seven... and sometimes both. I started just putting 3 rounds in a magazine. The first 4 didn't have many problems, if any.

I polished the extractor claw and that didn't seem to help. I don't know if I should take a bit off the lower inside of the claw so that the base rims can move under the claw better. It still seems like there's a connection between the follower and spring and maybe the magazine catch with rounds 5 and 6.

I'm thinking about scalloping the underside of the magazine catch if the next range session still results in a lot of FTFs. I won't lessen the ledge, just the angled underside... or just take a bit out of the ledge to cut down on its intrusion and interference with the follower or the spring. I did remove follower material where the catch would be. I guess the best thing would be to go put some rounds down range and see if firing is better than my racking the slide for FTF testing. Maybe it will be okay. I have a tired box of FMJ... all scratched up. I used a bit of lighter fluid to remove most of the Sharpie pen marks... seemed to building up in the chamber... and wiped all of the cases down with a used patch with some oil on it... not "wet", though. That cut down on the brass bits hanging off the cases.

Wynn

[TucsonMTB]

If this were a 1911, I would say too much extractor pressure and correct it.

Unfortunately, to reduce the extractor pressure on a Kahr, you have to shorten the last metal cylinder in the extractor spring train, and that's not reversible until you can get Kahr to ship you their part number 27 in the picture below. I suggest only filing on number 27 and keeping the ends square to ensure that everything else works.


Until you have a part 27 in hand to sacrifice by shortening, probably the best you can do is polish all the parts of the extractor train to ensure smooth operation. Also, use a piece of wood or something non-injurious to wiggle the extractor itself when you lubricate the slide after cleaning. Getting the lubricant into the mechanism will help. You can probably tell if the extractor is moving freely by manipulating it.

Disclaimer: This is all just cr@p I went through to eventually cure my stainless PM40 of failures to return to battery. My DLC gun only needed careful lubrication to get the extractor working well. I didn't even polish the extractor on the DLC gun, but sure did on the stainless gun. In other words, I could be wrong. Have you dropped Greg a PM asking him to look at your thread? It would be good to hear his analysis, if he is willing to jump in the way this fool has.

Edited to add: I don't think the magazine catch is part of the problem on you pistol. It probably is the extractor. One other item that needed attention on my PM40 was the breach face. I polished it with vertical strokes of very fine wet-or-dry paper. Mine had some serious tool marks.

[gb6491]

... It still seems like there's a connection between the follower and spring and maybe the magazine catch with rounds 5 and 6....
Wynn

Darn Wynn, you sure document a problem well
I tend to agree with your statement above as that came to mind when reading post #50. The jams in your photos look quite similar to some that happen when there is not enough resistance supplied for the slide to cycle fully. In that case, the slide arrives back in position earlier than it should to pick up the rounds correctly. In your case, I believe the slide is on time, but I think your follower is scraping on the catch and the spring is not getting the rounds up in time for the slide to pick them up correctly. I'd sand/cut the follower down to the point it can no longer contact the magazine latch (I do this on all my Kahr followers after running into issues with my CW45) and see if that helps.

... One other item that needed attention on my PM40 was the breach face. I polished it with vertical strokes of very fine wet-or-dry paper. Mine had some serious tool marks.

+1 on this. It could very well help get a late arriving round up under the extractor.

Regards,
Greg

[wyntrout]

Thanks, Greg. It just seems like there's several things going on to cause with regularity the FTF's on the third and second to last of 7 rounds... all where the follower and catch could contact. There's also a repeating scratch or long nick at about 4 o'clock at the case mouth as the case sits in the chamber, but I can't see or feel anything there.

I can easily slide a round in while pressing upwards and it will hang solidly. I wonder if taking a coil off the extractor spring would help... easier than shortening the rear pin.

I actually used a razor knife to carve some plastic off the follower on that mag catch corner and then sanded it, but still had the same hangups in the chamber.

I've polished, sanded a tiny bit, and polished some more, but I can still get the same FTFs, so I'm worried about doing any more of that, but something is causing that scratch at the lower right of the case mouth, especially on the ones that hang.

I want to go shoot it... put another 100 rounds or so through it and see if the same happens while actually firing. I tried to simulate that with enough "violence".

I only got 2-3 mags through that way without FTFs. Round #5 is tops and 6 next.

Wynn

[gb6491]

If you have any cratex tips (rubber polishing points) for your "dremel like tool" you might want to polish this edge just enough to break any sharpness (and nothing more) it may have:

I remove quite a bit of material when I mod my followers:
http://kahrtalk.com/showpost.php?p=15667&postcount=2
Regards,
Greg

[wyntrout]

Thanks, Greg, I think I'll work over my mag followers some more, before going to the range tomorrow.

I've worked over that area in red pretty well. I don't see how anything can be binding there. But there are those nicks... and I don't think they are from near the barrel rifling.

I got some good picks at Harbor Freight... orange handled icepick-looking things... one with a 1/2" 90° bend at the end and the other has a hook. The bent one is just right for the magazine catch spring. You can get the bend under the spring and just rotate it up out of the way, then move it a bit to get out of the way to slide the catch out... or in.

I'm about ready to take a nap until my wife goes to work ~ 7am... then I go to bed for a few hours... night owl.

Wynn

[TucsonMTB]

+1 on Greg's suggestion about removing quite a bit of plastic to provide clearance when modifying the follower. I do the same. But, I have to agree with you, Wynn, that the lower rounds are probably not a follower interference issue.

I also like the idea of using a rubber abrasive tip to polish that breaking point between the ramp and the chamber. I will probably examine mine in the morning, rather than disturb my wife with funny noises tonight. Thanks for the suggestion, Greg.

When it comes to reducing extractor tension to make it easier to get the cartridge rim under the extractor, you can trim the spring or grind the rear extractor pin. I chose to shorten the pin because of the parts costs and the greater ease in making small changes. The data below is from the Kahr site.

026PM4 Extractor Spring
Price: $6.60

027PM4 Extractor Pin Back
Price: $1.10

I would love to get my PM40s to reliably feed 180 grain rounds, so I will probably be breaking out the rubber abrasive and definitely shortening the the rear extractor pin (I do have a spare) before my next range trip.

Edited to add: I forgot to mention earlier that with one exception, my flush fit mags have the 5% stronger Wolffe magazine springs installed. It may not matter, but it can't (doesn't seem to) hurt. They are available in three packs and were purchased before the arrival of my second PM40 or they would all four have them. The fourth magazine, that does not have one, has given me a miss-feed at one of the lower rounds in the magazine, while shooting normally reliable 135 grain ammo, one time in the last 500 rounds. Could just be a coincidence, but eventually I will get a stronger spring.

[JFootin]

Edited to add: I forgot to mention earlier that with one exception, my flush fit mags have the 5% stronger Wolffe magazine springs installed. It may not matter, but it can't (doesn't seem to) hurt. They are available in three packs and were purchased before the arrival of my second PM40 or they would all four have them. The fourth magazine, that does not have one, has given me a miss-feed at one of the lower rounds in the magazine, while shooting normally reliable 135 grain ammo, one time in the last 500 rounds. Could just be a coincidence, but eventually I will get a stronger spring.

Hmmm. Somebody the other day posted that he had weakened his mag springs to solve a feeding issue. Gee, I wish Kahr would get these mags right!

[jocko]

as u know sometimes one does something to his gun to make it right that will not work in the other 99%, so IMO take very corrective comment given with a grain of salt. None is set in stone. Not sure kahr has a total handle on iut either.. I have never been a blelkiever that factory kahr mag springs are too strong. I use the 5% more strength and they are super, It isn't like 5% is a deal breaker either. Wolffs knows springs. We tend to think WE KNOW SPRINGS.

[wyntrout]

I think the design of the spring... smaller "diameter" and able to wiggle around in the magazine tube, instead of filling all but the corners and collapsing in a column, is part of the problem. As the follower gets in the area of the retention slot and the magazine catch, there is impediment of the follower and seemingly the spring at times.

I've noticed that that steel-pin actuator in the follower sticks out and catches on the top of the magazine tube as you try to insert bullets and it pushes the follower to the other side of the tube while depressed, maintaining drag on the left side of the tube, as well.

I wish that they developed an all-SS follower with sufficient skirt to keep it centered in the tube and allow at least one more round capacity. A lot of other companies have done this, including many designs for the 1911 magazines.

Wynn

[jocko]

that steel pin should not catch, wyn,m file it back a tad if it does. I think this spring thing is way over emphasized to. 99% of all kahr magas work as designed, when one doesn't it needs to be replace or at least maybe the internals looked. Many other gun companies seem to replace magazines first when there is issues in that area. so I really don't think it is pandemic to kahr more than any other, EXCPET the magazine spllitting thing, that is an issue kahr needs to get right.

[wyntrout]

Well, I went to the range with my loaded magazines... didn't feel like emptying them and screwing with the followers today... wanted to see how the pistol really worked in live fire.

I had my 6 mags loaded with different ammo... mostly MFS/Fiocchi 180-gr FMJ, then mags of 165-gr Speer Gold Dots, 165-gr Winchester PDX1, and 180-gr Remington UMC JHP. I started with the MFS... no problems... none with any mags on the first round! Yeehaa! Then I had a few FTFs on the next round, but still for the most part, full mags without problems.

Shooting that P40 is fun! But I gave up on left-handed... after 4-5 shots, the pad of my left index finger was hurting and I decided that was enough pain! Right handed wasn't too bad... not as accurate. AND, after watching Top Shot the other night and the shooting from the hip, I tried some of that with the target at 10 feet. I had to settle for stomach/COM-high, almost, because of the danged counter/table/whatever in the way. This kind of shooting can be hazardous with the Magna-Porting... I kind of felt some blow back and was glad I had shooting glasses on. No close to your body firing should be attempted as you could blow stuff up your nose or into your eyes. This could come in handy if you're wrestling someone for control of the pistol and the ports get pointed his way!

Anyhow, I took lots of pictures of the targets and FTFs and some of the groups were good.. when I couldn't see where the bullet impacted, it was usually in the darker bullseye. I could sure sprinkle the rounds around sometimes, though. I have to get ready for supper, so I don't have time for pictures, yet. I didn't do any video, though.

I had a lot less FTFs and a few rounds hung against the lower part of the feed ramp, so the mags need some TLC... or rather, major modifications!

I shot 3 boxes of the MFS FMJ FN... one was the much loaded and ejected at home,,, and at least 14 rounds each of the Remington JHP and Speer GDs, and about 7 or more, not sure, of the Winchester PDX1 165-gr.

Today's round count was 187, bringing the total up to about 583 by me, added to about 100 by 10kahrs, for a grand total of about 680.

More later!

Wynn