Todoay I tested out my New MK40. I ran a total of 350 rounds through it with overall good results but not perfect! I had and odd failure that I have never seen before. Sometimes after the 1st round was fired the slide locked back prematurely instead of chambering the next round! This happened a total of 5 times in the 350 rounds fired, 3 times up to 180 rounds and 1 around shot 270 and one last time at shot 320. What might cause this? All I had to do to clear it was hit the slide release. The slide always locked back on the last round as it should.
    I tried limping wristing it to see how it handled it, no problem at all! I did have one jam where one bullet did not chamber fully on shot 325 and I think it was because the gus was getting EXTREEMLY dirty! Accuracy was great sights were just about perfect(see picture)
    Another problem I found was the .40 kicks hard in this little gun. The frame gave me a good cut from the repeeted slamming into my thumb joint(see picture) No matter how I held the gun it keept on rubbing off my skin whichI just toughed out as I was enjoying shooting this little brute!
    Also I noticed tha the last shell ejected was always crushed around the mouth. I also have never seen a hand gun do that to a shell. The middle shells were ejeced normally for the most part.


Here are a couple pic of the groups I got from a rest at 10 yards.


This is the best 6 shot group I got at 10 yards.


My cut on my hand from this little gun!


The last shell ejected always looked like this! What would cause this??



More shells.The ones in front were ejected before the last shell and look normal.


This is a normal shell but even these have nasty scrapes on them. Does this look like a problem?


Same shell as above. Notice how it is bent a little? Most shells looked like this....is this normal for a Kahr?


One last shot of the nasty fouling after 350 rounds. Not the best picture but you get the idea.

I'm going to do a little more testing but I think I can get this MK40 running 100% with a little more break in and a good cleaning! I plan to CCW this little beast! Hope you enjoy the pictures and any help with the above problems I greatly appreciate!!!!! Thanks!

My Girlfriend has a Khar pm9 micro and had similar problems when using the extended mag. Problem solved when she put upward pressure on the botttom of the mag or used the mag that went flush with the bottom of the grip. Hope that helps!
-jls7

Read the rest pf ur post... dont know wtf is going on with the shell casings.
-jls7

Quoted: My Girlfriend has a Khar pm9 micro and had similar problems when using the extended mag. Problem solved when she put upward pressure on the botttom of the mag or used the mag that went flush with the bottom of the grip. Hope that helps! -jls7

It was the extended that this happened with. The smaller mag never did this.

Bump.

The premature lockup is most likely from your slide stop being slightly out of spec. The bullet ogive hits the slide stop when coming up in the magazine causing the slide stop to catch the slide.  My mk40 was and i sent it back. Also they replaced the recoil spring and guide, i had the wrong version as they had updated the gun when i bought mine and it was a mix of new and old.  worked perfectly after.  don't know the deal on the crushed casing thing.  Maybe break in will help that.
I'm trying to remember if i had that with the last round.  Ejection disturbed by magazine follower?Hold on I have a copy of the letter I sent with my gun.  Nope read the letter, i had the same magazine/slide stop issue and my slide failed to close sometimes.  the second failure was  from the mismatched parts. They also honed out the front of the slide where the barrel contacts the slide to allow better lockup.


Edited to add that 180s are more prone to jamming because of bullet length.  I might practice with some 180 ball ammo but I carry Gold Dot 155s.  The short slide cycle length and timing are sensitive to bullet lenth and magazine function.  Excessively dirty mags will give you grief.  I doubt many of us will have a carry gun that is carboned up badly.  But pocket lint in a spare mag is a possibility to watch out for.

SoS

My MK9 will bend casings like your 7th pic (of just one round) but haven't had the problme of slide lock. Call Kahr and tell them about it. They will most likely have you send it in, but they can also send you a new slide lock. Talk to Dottie.

Thanks!!!! I'm going to do one more range session to see if it is any better. I cleaned it 100% so now that it is clean and has had 350 rounds through it, it might be ok now. I'll post back!

They'll most likely file grind off a bit of the slide stop.  

The slide stop projection shouldn't touch the bullet at all.  Most likely is sticking out too far to the right to contact the bullet.  The only thing it should contact is the magazine follower when it comes up, and only then should it press upward to catch the slide.

The other issue with crushed cases I can only guess is an ejector issue.

Do tell us what Kahr says and how the repairs work out.

SoS

Quoted: Do tell us what Kahr says and how the repairs work out. SoS

Will do!

I would watch your right thumb placement. Because these guns are so small, it's really easy for your   right thumb to brush up on the slide release when it recoils. I had more than a few lock backs at first, and I couldn't see anything wrong with the pistol. But then I changed my grip holding my thumb away from the slide release then my p-9 ran perfectly after that.

Quoted: I would watch your right thumb placement. Because these guns are so small, it's really easy for your   right thumb to brush up on the slide release when it recoils. I had more than a few lock backs at first, and I couldn't see anything wrong with the pistol. But then I changed my grip holding my thumb away from the slide release then my p-9 ran perfectly after that.

Good advice and thank you!